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Lecture_Presentation_14.pptxCampbell Essential Biology, Seventh Edition, and Campbell Essential Biology with Physiology, Sixth Edition
Chapter 14
How Biological
Diversity Evolves
PowerPoint® Lectures created by Edward J. Zalisko, Eric J. Simon, Jean L. Dickey, and Jane B. Reece
Copyright © 2021 Pearson Education, Inc. All Rights Reserved
Copyright © 2021 Pearson Education, Inc. All Rights Reserved
1
If Rocks Could Speak, What Would they Tell Us? Several Hundred Million Years of History is “Written” in the Layers of Rock in the Grand Canyon
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2
2
Biology and Society: Humanity’s Footprint (1 of 2)
Humanity has had an extraordinary effect on the ecology and geology of Earth.
Our indelible footprint includes
the transport of organisms far from their natural homes,
the prevalence of agriculture and domesticated animals,
the existence of manufactured materials such as plastics and concrete,
radioactivity from testing nuclear weapons, and
climate-altering emissions from burning fossil fuels.
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3
Biology and Society: Humanity’s Footprint (2 of 2)
The irreversibility of these changes has led some scientists to propose that a new epoch in Earth’s history has begun: the Anthropocene.
The Anthropocene signals a significant shift in the geologic record that includes a high rate of extinction and accelerating change to Earth.
Human-driven changes in the environment also bring about evolutionary change in populations of organisms, including pesticide-resistant insects and antibiotic-resistant bacteria.
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4
4
Tailings (Waste Residue) Dump from Mining Oil Sands in Alberta, Canada
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5
The Origin of Species
In the 150 years since the publication of Darwin’s book On the Origin of Species by Means of Natural Selection, new discoveries and technological advances have given scientists a wealth of new information about the evolution of life.
The diversity of life evolved through speciation, the process in which one species splits into two or more species.
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Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geologic terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as to occur every 1,000 years, are actually common in geologic terms. Students might not realize that 1,000 such “1 in a thousand” events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? This grouping of kinds, the existence of natural groups, is related to common ancestry.
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geologic event. Ask your students to think back to news footage of torrential rains, massive debris rocketing down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such an event. Dramatic weather and geologic events may be rare in our lifetimes, but they are frequent enough to play a role in speciation.
3. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: wwx.inhs.illinois.edu/collections/herps/data/ilspecies/am_platine/.
4. The abundance of polyploid plants used for food facilitates further study for student assignments. Perhaps small groups or individuals can select a polyploid crop and describe its evolutionary history and/or its current method of reproduction.
5. An analogy might be made between the specialized functions of finch beaks and the many types of screwdrivers (or pliers) that exist today. Each type of screwdriver (Phillips, flathead, hex, and so on) represents a specialization for a particular job or a generalist approach, useful in a variety of applications.
Active Lecture Tips
1. Before lecturing about species concepts, have students work in small groups, without the benefit of books, to define a species. They might begin by simply creating a list of the properties of species.
A Marine Iguana (Right), An Example of the Unique Species Inhabiting the Galápagos
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What is a Species? (1 of 2)
Species is a Latin word meaning “kind” or “appearance.”
The biological species concept defines a species as “a group of populations whose members have the potential to interbreed with one another in nature and produce fertile offspring (offspring that can reproduce).”
The biological species concept cannot be applied in all situations, including asexual organisms and fossils.
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8
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geologic terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as to occur every 1,000 years, are actually common in geologic terms. Students might not realize that 1,000 such “1 in a thousand” events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? This grouping of kinds, the existence of natural groups, is related to common ancestry.
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geologic event. Ask your students to think back to news footage of torrential rains, massive debris rocketing down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such an event. Dramatic weather and geologic events may be rare in our lifetimes, but they are frequent enough to play a role in speciation.
3. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: wwx.inhs.illinois.edu/collections/herps/data/ilspecies/am_platine/.
4. The abundance of polyploid plants used for food facilitates further study for student assignments. Perhaps small groups or individuals can select a polyploid crop and describe its evolutionary history and/or its current method of reproduction.
5. An analogy might be made between the specialized functions of finch beaks and the many types of screwdrivers (or pliers) that exist today. Each type of screwdriver (Phillips, flathead, hex, and so on) represents a specialization for a particular job or a generalist approach, useful in a variety of applications.
Active Lecture Tips
1. Before lecturing about species concepts, have students work in small groups, without the benefit of books, to define a species. They might begin by simply creating a list of the properties of species.
The Biological Species Concept is Based on Reproductive Compatibility Rather than Physical Similarity
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What is a Species? (2 of 2)
Biologists may also define a species
according to measurable physical traits,
solely on the basis of molecular data, a sort of bar code that identifies each species, or
as the smallest group of individuals sharing a common ancestor and forming one branch on the tree of life.
Checkpoint: According to the biological species concept, what defines a species?
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10
Checkpoint response: the ability of its members to interbreed with one another and produce fertile offspring in a natural setting
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geologic terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as to occur every 1,000 years, are actually common in geologic terms. Students might not realize that 1,000 such “1 in a thousand” events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? This grouping of kinds, the existence of natural groups, is related to common ancestry.
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geologic event. Ask your students to think back to news footage of torrential rains, massive debris rocketing down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such an event. Dramatic weather and geologic events may be rare in our lifetimes, but they are frequent enough to play a role in speciation.
3. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: wwx.inhs.illinois.edu/collections/herps/data/ilspecies/am_platine/.
4. The abundance of polyploid plants used for food facilitates further study for student assignments. Perhaps small groups or individuals can select a polyploid crop and describe its evolutionary history and/or its current method of reproduction.
5. An analogy might be made between the specialized functions of finch beaks and the many types of screwdrivers (or pliers) that exist today. Each type of screwdriver (Phillips, flathead, hex, and so on) represents a specialization for a particular job or a generalist approach, useful in a variety of applications.
Active Lecture Tips
1. Before lecturing about species concepts, have students work in small groups, without the benefit of books, to define a species. They might begin by simply creating a list of the properties of species.
Reproductive Barriers Between Species
A reproductive barrier is anything that prevents individuals of closely related species from interbreeding.
Prezygotic barriers prevent mating or fertilization between species.
Postzygotic barriers operate if
interspecies mating occurs and
hybrid zygotes form.
Checkpoint: Why is behavioral isolation considered a prezygotic barrier?
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11
Checkpoint response: because it prevents mating and therefore the formation of a zygote
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geologic terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as to occur every 1,000 years, are actually common in geologic terms. Students might not realize that 1,000 such “1 in a thousand” events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? This grouping of kinds, the existence of natural groups, is related to common ancestry.
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geologic event. Ask your students to think back to news footage of torrential rains, massive debris rocketing down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such an event. Dramatic weather and geologic events may be rare in our lifetimes, but they are frequent enough to play a role in speciation.
3. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: wwx.inhs.illinois.edu/collections/herps/data/ilspecies/am_platine/.
4. The abundance of polyploid plants used for food facilitates further study for student assignments. Perhaps small groups or individuals can select a polyploid crop and describe its evolutionary history and/or its current method of reproduction.
5. An analogy might be made between the specialized functions of finch beaks and the many types of screwdrivers (or pliers) that exist today. Each type of screwdriver (Phillips, flathead, hex, and so on) represents a specialization for a particular job or a generalist approach, useful in a variety of applications.
Active Lecture Tips
1. Before lecturing about species concepts, have students work in small groups, without the benefit of books, to define a species. They might begin by simply creating a list of the properties of species.
Reproductive Barriers Between Closely Related Species
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Prezygotic Barriers
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Postzygotic Barriers
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14
Video: Albatross Courtship Ritual
https://mediaplayer.pearsoncmg.com/assets/secs-bio-video-albatross-courtship-ritual
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15
15
Video: Blue-footed Boobies Courtship Ritual
https://mediaplayer.pearsoncmg.com/assets/secs-blue-footed-boobies-courtship-ritual
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16
Video: Giraffe Courtship Ritual
https://mediaplayer.pearsoncmg.com/assets/secs-bio-video-giraffe-courtship-ritual
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17
Evolution: Mechanisms of Speciation
A key event in the origin of a species occurs when a population is somehow cut off from other populations of the parent species.
Species can form by
allopatric speciation, in which the initial block to gene flow is a geographic barrier that physically isolates the splinter population, or
sympatric speciation, without geographic isolation.
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18
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geologic terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as to occur every 1,000 years, are actually common in geologic terms. Students might not realize that 1,000 such “1 in a thousand” events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? This grouping of kinds, the existence of natural groups, is related to common ancestry.
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geologic event. Ask your students to think back to news footage of torrential rains, massive debris rocketing down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such an event. Dramatic weather and geologic events may be rare in our lifetimes, but they are frequent enough to play a role in speciation.
3. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: wwx.inhs.illinois.edu/collections/herps/data/ilspecies/am_platine/.
4. The abundance of polyploid plants used for food facilitates further study for student assignments. Perhaps small groups or individuals can select a polyploid crop and describe its evolutionary history and/or its current method of reproduction.
5. An analogy might be made between the specialized functions of finch beaks and the many types of screwdrivers (or pliers) that exist today. Each type of screwdriver (Phillips, flathead, hex, and so on) represents a specialization for a particular job or a generalist approach, useful in a variety of applications.
Active Lecture Tips
1. Before lecturing about species concepts, have students work in small groups, without the benefit of books, to define a species. They might begin by simply creating a list of the properties of species.
Allopatric Speciation
A variety of geologic processes can isolate populations.
Speciation occurs with the evolution of reproductive barriers between the isolated population and its parent population.
Even if the two populations should come back into contact at some later time, the reproductive barriers will keep them as separate species.
Checkpoint: What is necessary for allopatric speciation to occur?
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19
Checkpoint response: A population must be split into more than one group by a geographic barrier that interrupts gene flow between the two groups.
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geologic terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as to occur every 1,000 years, are actually common in geologic terms. Students might not realize that 1,000 such “1 in a thousand” events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? This grouping of kinds, the existence of natural groups, is related to common ancestry.
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geologic event. Ask your students to think back to news footage of torrential rains, massive debris rocketing down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such an event. Dramatic weather and geologic events may be rare in our lifetimes, but they are frequent enough to play a role in speciation.
3. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: wwx.inhs.illinois.edu/collections/herps/data/ilspecies/am_platine/.
4. The abundance of polyploid plants used for food facilitates further study for student assignments. Perhaps small groups or individuals can select a polyploid crop and describe its evolutionary history and/or its current method of reproduction.
5. An analogy might be made between the specialized functions of finch beaks and the many types of screwdrivers (or pliers) that exist today. Each type of screwdriver (Phillips, flathead, hex, and so on) represents a specialization for a particular job or a generalist approach, useful in a variety of applications.
Active Lecture Tips
1. Before lecturing about species concepts, have students work in small groups, without the benefit of books, to define a species. They might begin by simply creating a list of the properties of species.
Allopatric Speciation of Antelope Squirrels on Opposite Rims of the Grand Canyon
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20
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Possible Outcomes After Geographic Isolation of Populations
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Video: Grand Canyon
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22
Sympatric Speciation (1 of 2)
In sympatric speciation, a new species arises within the same geographic area as its parent species.
Factors that can reduce gene flow in sympatric populations include
polyploidy, in which a species may originate from an accident during cell division that results in an extra set of chromosomes,
habitat complexity, and
sexual selection.
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23
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geologic terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as to occur every 1,000 years, are actually common in geologic terms. Students might not realize that 1,000 such “1 in a thousand” events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? This grouping of kinds, the existence of natural groups, is related to common ancestry.
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geologic event. Ask your students to think back to news footage of torrential rains, massive debris rocketing down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such an event. Dramatic weather and geologic events may be rare in our lifetimes, but they are frequent enough to play a role in speciation.
3. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: wwx.inhs.illinois.edu/collections/herps/data/ilspecies/am_platine/.
4. The abundance of polyploid plants used for food facilitates further study for student assignments. Perhaps small groups or individuals can select a polyploid crop and describe its evolutionary history and/or its current method of reproduction.
5. An analogy might be made between the specialized functions of finch beaks and the many types of screwdrivers (or pliers) that exist today. Each type of screwdriver (Phillips, flathead, hex, and so on) represents a specialization for a particular job or a generalist approach, useful in a variety of applications.
Active Lecture Tips
1. Before lecturing about species concepts, have students work in small groups, without the benefit of books, to define a species. They might begin by simply creating a list of the properties of species.
Sympatric Speciation (2 of 2)
Two distinct forms of polyploid speciation have been observed.
In one form, polyploidy arises from a single parent species. A failure of cell division might double the chromosome number from the original diploid number (2n) to tetraploid (4n).
A second form of polyploid speciation can occur when two different species interbreed and produce hybrid offspring.
Many of the plant species we grow for food are polyploids, including oats, potatoes, bananas, strawberries, peanuts, apples, sugarcane, and wheat.
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24
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geologic terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as to occur every 1,000 years, are actually common in geologic terms. Students might not realize that 1,000 such “1 in a thousand” events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? This grouping of kinds, the existence of natural groups, is related to common ancestry.
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geologic event. Ask your students to think back to news footage of torrential rains, massive debris rocketing down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such an event. Dramatic weather and geologic events may be rare in our lifetimes, but they are frequent enough to play a role in speciation.
3. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: wwx.inhs.illinois.edu/collections/herps/data/ilspecies/am_platine/.
4. The abundance of polyploid plants used for food facilitates further study for student assignments. Perhaps small groups or individuals can select a polyploid crop and describe its evolutionary history and/or its current method of reproduction.
5. An analogy might be made between the specialized functions of finch beaks and the many types of screwdrivers (or pliers) that exist today. Each type of screwdriver (Phillips, flathead, hex, and so on) represents a specialization for a particular job or a generalist approach, useful in a variety of applications.
Active Lecture Tips
1. Before lecturing about species concepts, have students work in small groups, without the benefit of books, to define a species. They might begin by simply creating a list of the properties of species.
Gray Tree Frog
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25
25
Chinese Hibiscus
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26
Sympatric Speciation in a Plant
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The Process of Science: Do Human Activities Facilitate Speciation? (1 of 2)
Background: As humans travel the world, we often transport plants, animals, and other organisms to regions beyond their natural range.
These activities create opportunities for hybridization that would not otherwise exist.
Fifty years after the introduction of the plant goatsbeard (a weedy member of the daisy family) to the United States, a botanist discovered that hybridization had produced two new species.
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Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geologic terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as to occur every 1,000 years, are actually common in geologic terms. Students might not realize that 1,000 such “1 in a thousand” events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? This grouping of kinds, the existence of natural groups, is related to common ancestry.
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geologic event. Ask your students to think back to news footage of torrential rains, massive debris rocketing down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such an event. Dramatic weather and geologic events may be rare in our lifetimes, but they are frequent enough to play a role in speciation.
3. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: wwx.inhs.illinois.edu/collections/herps/data/ilspecies/am_platine/.
4. The abundance of polyploid plants used for food facilitates further study for student assignments. Perhaps small groups or individuals can select a polyploid crop and describe its evolutionary history and/or its current method of reproduction.
5. An analogy might be made between the specialized functions of finch beaks and the many types of screwdrivers (or pliers) that exist today. Each type of screwdriver (Phillips, flathead, hex, and so on) represents a specialization for a particular job or a generalist approach, useful in a variety of applications.
Active Lecture Tips
1. Before lecturing about species concepts, have students work in small groups, without the benefit of books, to define a species. They might begin by simply creating a list of the properties of species.
The Process of Science: Do Human Activities Facilitate Speciation? (2 of 2)
Method: Researchers conducted tests to determine how one new species (Tragopogon mirus) formed.
Results: Results supported the hypothesis that Tragopogon mirus originated by polyploid speciation.
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29
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geologic terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as to occur every 1,000 years, are actually common in geologic terms. Students might not realize that 1,000 such “1 in a thousand” events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? This grouping of kinds, the existence of natural groups, is related to common ancestry.
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geologic event. Ask your students to think back to news footage of torrential rains, massive debris rocketing down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such an event. Dramatic weather and geologic events may be rare in our lifetimes, but they are frequent enough to play a role in speciation.
3. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: wwx.inhs.illinois.edu/collections/herps/data/ilspecies/am_platine/.
4. The abundance of polyploid plants used for food facilitates further study for student assignments. Perhaps small groups or individuals can select a polyploid crop and describe its evolutionary history and/or its current method of reproduction.
5. An analogy might be made between the specialized functions of finch beaks and the many types of screwdrivers (or pliers) that exist today. Each type of screwdriver (Phillips, flathead, hex, and so on) represents a specialization for a particular job or a generalist approach, useful in a variety of applications.
Active Lecture Tips
1. Before lecturing about species concepts, have students work in small groups, without the benefit of books, to define a species. They might begin by simply creating a list of the properties of species.
Testing a Hypothesis about Speciation
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Island Showcases of Speciation (1 of 2)
Volcanic islands, such as the Galápagos and Hawaiian island chains, are initially devoid of life.
Over time, colonists arrive via ocean currents or winds.
In their new environment, these populations may diverge significantly from their distant parent populations.
In addition, islands that have physically diverse habitats and that are far enough apart to permit populations to evolve in isolation but close enough to allow occasional dispersals to occur are often the sites of multiple speciation events.
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31
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geologic terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as to occur every 1,000 years, are actually common in geologic terms. Students might not realize that 1,000 such “1 in a thousand” events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? This grouping of kinds, the existence of natural groups, is related to common ancestry.
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geologic event. Ask your students to think back to news footage of torrential rains, massive debris rocketing down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such an event. Dramatic weather and geologic events may be rare in our lifetimes, but they are frequent enough to play a role in speciation.
3. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: wwx.inhs.illinois.edu/collections/herps/data/ilspecies/am_platine/.
4. The abundance of polyploid plants used for food facilitates further study for student assignments. Perhaps small groups or individuals can select a polyploid crop and describe its evolutionary history and/or its current method of reproduction.
5. An analogy might be made between the specialized functions of finch beaks and the many types of screwdrivers (or pliers) that exist today. Each type of screwdriver (Phillips, flathead, hex, and so on) represents a specialization for a particular job or a generalist approach, useful in a variety of applications.
Active Lecture Tips
1. Before lecturing about species concepts, have students work in small groups, without the benefit of books, to define a species. They might begin by simply creating a list of the properties of species.
Island Showcases of Speciation (2 of 2)
The Galápagos Islands are one of the world’s great showcases of speciation.
For example, the islands have 14 species of closely related finches.
These birds share many finch-like traits, but they differ in their feeding habits, their habitats, and their beaks, which are specialized for what they eat.
The distinctive beaks adapted for the specific diets of the different species of finches are an example of the correlation between structure and function.
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32
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geologic terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as to occur every 1,000 years, are actually common in geologic terms. Students might not realize that 1,000 such “1 in a thousand” events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? This grouping of kinds, the existence of natural groups, is related to common ancestry.
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geologic event. Ask your students to think back to news footage of torrential rains, massive debris rocketing down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such an event. Dramatic weather and geologic events may be rare in our lifetimes, but they are frequent enough to play a role in speciation.
3. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: wwx.inhs.illinois.edu/collections/herps/data/ilspecies/am_platine/.
4. The abundance of polyploid plants used for food facilitates further study for student assignments. Perhaps small groups or individuals can select a polyploid crop and describe its evolutionary history and/or its current method of reproduction.
5. An analogy might be made between the specialized functions of finch beaks and the many types of screwdrivers (or pliers) that exist today. Each type of screwdriver (Phillips, flathead, hex, and so on) represents a specialization for a particular job or a generalist approach, useful in a variety of applications.
Active Lecture Tips
1. Before lecturing about species concepts, have students work in small groups, without the benefit of books, to define a species. They might begin by simply creating a list of the properties of species.
Galápagos Finches with Beaks Adapted for Specific Diets
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Observing Speciation in Progress (1 of 2)
In contrast to microevolutionary change, which may be apparent within a few generations, the process of speciation is often extremely slow.
But we can see speciation occurring.
Researchers have documented at least two dozen cases in which populations are currently diverging as they
use different food resources or
breed in different habitats.
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34
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geologic terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as to occur every 1,000 years, are actually common in geologic terms. Students might not realize that 1,000 such “1 in a thousand” events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? This grouping of kinds, the existence of natural groups, is related to common ancestry.
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geologic event. Ask your students to think back to news footage of torrential rains, massive debris rocketing down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such an event. Dramatic weather and geologic events may be rare in our lifetimes, but they are frequent enough to play a role in speciation.
3. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: wwx.inhs.illinois.edu/collections/herps/data/ilspecies/am_platine/.
4. The abundance of polyploid plants used for food facilitates further study for student assignments. Perhaps small groups or individuals can select a polyploid crop and describe its evolutionary history and/or its current method of reproduction.
5. An analogy might be made between the specialized functions of finch beaks and the many types of screwdrivers (or pliers) that exist today. Each type of screwdriver (Phillips, flathead, hex, and so on) represents a specialization for a particular job or a generalist approach, useful in a variety of applications.
Active Lecture Tips
1. Before lecturing about species concepts, have students work in small groups, without the benefit of books, to define a species. They might begin by simply creating a list of the properties of species.
Observing Speciation in Progress (2 of 2)
Much of the evidence for evolution comes from the fossil record.
In one survey of 84 groups of plants and animals, the time for speciation ranged from 4,000 to 40 million years.
The cumulative effects of multiple speciations, as well as extinctions, have shaped the dramatic changes documented in the fossil record.
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35
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geologic terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as to occur every 1,000 years, are actually common in geologic terms. Students might not realize that 1,000 such “1 in a thousand” events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? This grouping of kinds, the existence of natural groups, is related to common ancestry.
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geologic event. Ask your students to think back to news footage of torrential rains, massive debris rocketing down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such an event. Dramatic weather and geologic events may be rare in our lifetimes, but they are frequent enough to play a role in speciation.
3. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species: wwx.inhs.illinois.edu/collections/herps/data/ilspecies/am_platine/.
4. The abundance of polyploid plants used for food facilitates further study for student assignments. Perhaps small groups or individuals can select a polyploid crop and describe its evolutionary history and/or its current method of reproduction.
5. An analogy might be made between the specialized functions of finch beaks and the many types of screwdrivers (or pliers) that exist today. Each type of screwdriver (Phillips, flathead, hex, and so on) represents a specialization for a particular job or a generalist approach, useful in a variety of applications.
Active Lecture Tips
1. Before lecturing about species concepts, have students work in small groups, without the benefit of books, to define a species. They might begin by simply creating a list of the properties of species.
Earth History and Macroevolution
Macroevolution
is evolutionary change above the species level and
includes the impact of mass extinctions on the diversity of life and the origin of key adaptations such as flight.
An understanding of macroevolution begins with a look at the span of geologic time over which life’s diversity has evolved.
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36
Student Misconceptions and Concerns
1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 × 60 × 24 × 365 = 31,536,000) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day).
2. Students also need to be reminded that 1 billion is 1,000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error.
Teaching Tips
1. The sequence, but not absolute ages, is revealed by the stratifications in sedimentary rocks. This is like peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence, we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed.
2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations.
3. The consequences of an asteroid impact, large or small, illustrate the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of Earth!
Active Lecture Tips
1. Challenge your students to work in pairs to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species.
The Fossil Record (1 of 2)
Fossils are evidence of organisms that lived in the past. The fossil record is the sequence in which fossils appear in rock strata and an archive of macroevolution.
The geologic time scale divides Earth’s history into a consistent sequence of geologic periods.
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37
Student Misconceptions and Concerns
1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 × 60 × 24 × 365 = 31,536,000) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day).
2. Students also need to be reminded that 1 billion is 1,000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error.
Teaching Tips
1. The sequence, but not absolute ages, is revealed by the stratifications in sedimentary rocks. This is like peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence, we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed.
2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations.
3. The consequences of an asteroid impact, large or small, illustrate the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of Earth!
Active Lecture Tips
1. Challenge your students to work in pairs to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species.
Strata of Sedimentary Rock at the Grand Canyon
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The Geologic Time Scale
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Animation: The Geologic Record
https://mediaplayer.pearsoncmg.com/assets/secs-campbell-scrolling-geologic-record
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Animation: Macroevolution
https://mediaplayer.pearsoncmg.com/assets/secs-campbell-macroevolution
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The Fossil Record (2 of 2)
The most common method geologists use to learn the ages of rocks and the fossils they contain is radiometric dating, a method based on the decay of radioactive isotopes.
Another commonly used method is to date layers of volcanic rock or ash above and below the sedimentary layer in which fossils are found; by inference, the age of the fossils is between those two dates.
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42
Student Misconceptions and Concerns
1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 × 60 × 24 × 365 = 31,536,000) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day).
2. Students also need to be reminded that 1 billion is 1,000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error.
Teaching Tips
1. The sequence, but not absolute ages, is revealed by the stratifications in sedimentary rocks. This is like peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence, we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed.
2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations.
3. The consequences of an asteroid impact, large or small, illustrate the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of Earth!
Active Lecture Tips
1. Challenge your students to work in pairs to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species.
Plate Tectonics and Biogeography (1 of 3)
According to the theory of plate tectonics, the continents and seafloors form a thin outer layer of solid rock, called the crust, divided into giant, irregularly shaped plates that float atop the mantle, a mass of hot, viscous material.
In a process called continental drift, movements in the mantle cause the plates to move.
The boundaries of some plates are hotspots of geologic activity.
Earthquakes signal that two plates are scraping past or colliding with each other.
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43
Student Misconceptions and Concerns
1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 × 60 × 24 × 365 = 31,536,000) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day).
2. Students also need to be reminded that 1 billion is 1,000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error.
Teaching Tips
1. The sequence, but not absolute ages, is revealed by the stratifications in sedimentary rocks. This is like peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence, we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed.
2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations.
3. The consequences of an asteroid impact, large or small, illustrate the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of Earth!
Active Lecture Tips
1. Challenge your students to work in pairs to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species.
Cutaway View of Earth
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Earth’s Tectonic Plates
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Plate Tectonics and Biogeography (2 of 3)
Continental drift has had a tremendous impact on the evolution of life’s diversity by
reshaping the physical features of the planet and
altering the environments in which organisms live.
About 250 million years ago, plate movements formed the supercontinent Pangaea,
reducing the total amount of shoreline,
deepening ocean basins, and
lowering sea levels.
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Student Misconceptions and Concerns
1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 × 60 × 24 × 365 = 31,536,000) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day).
2. Students also need to be reminded that 1 billion is 1,000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error.
Teaching Tips
1. The sequence, but not absolute ages, is revealed by the stratifications in sedimentary rocks. This is like peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence, we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed.
2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations.
3. The consequences of an asteroid impact, large or small, illustrate the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of Earth!
Active Lecture Tips
1. Challenge your students to work in pairs to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species.
The History of Plate Tectonics
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Plate Tectonics and Biogeography (3 of 3)
The second dramatic chapter in the history of continental drift began during the mid-Mesozoic era.
Pangaea started to break up, causing geographic isolation of colossal proportions.
As the landmasses drifted apart, each continent became a separate evolutionary arena as its climates changed and its organisms diverged.
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Student Misconceptions and Concerns
1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 × 60 × 24 × 365 = 31,536,000) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day).
2. Students also need to be reminded that 1 billion is 1,000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error.
Teaching Tips
1. The sequence, but not absolute ages, is revealed by the stratifications in sedimentary rocks. This is like peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence, we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed.
2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations.
3. The consequences of an asteroid impact, large or small, illustrate the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of Earth!
Active Lecture Tips
1. Challenge your students to work in pairs to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species.
Plate Tectonics and Biogeography
The history of continental mergers and separations explains patterns of biogeography, the study of the past and present distribution of organisms.
Continental drift also separated Australia from other landmasses.
Australia and its neighboring islands are home to more than 200 species of marsupials, most of which are found nowhere else in the world.
Checkpoint: If marsupials originated in Asia and reached Australia via South America, where else should paleontologists find fossil marsupials?
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Checkpoint response: Antarctica
Student Misconceptions and Concerns
1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 × 60 × 24 × 365 = 31,536,000) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day).
2. Students also need to be reminded that 1 billion is 1,000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error.
Teaching Tips
1. The sequence, but not absolute ages, is revealed by the stratifications in sedimentary rocks. This is like peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence, we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed.
2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations.
3. The consequences of an asteroid impact, large or small, illustrate the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of Earth!
Active Lecture Tips
1. Challenge your students to work in pairs to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species.
Australian Marsupials
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50
Mass Extinctions and Explosive Diversifications of Life
The fossil record reveals five mass extinctions over the last 540 million years. In each of these events, 50% or more of Earth’s species died out.
The Permian mass extinction, at about the time Pangaea formed, claimed about 96% of marine species and impacted terrestrial life as well.
The Cretaceous extinction occurred about 66 million years ago and included the extinction of all the dinosaurs except birds, permitting an explosive increase in diversity of mammals.
Extinctions seem to have provided the surviving organisms with new environmental opportunities.
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Student Misconceptions and Concerns
1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 × 60 × 24 × 365 = 31,536,000) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day).
2. Students also need to be reminded that 1 billion is 1,000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error.
Teaching Tips
1. The sequence, but not absolute ages, is revealed by the stratifications in sedimentary rocks. This is like peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence, we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed.
2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations.
3. The consequences of an asteroid impact, large or small, illustrate the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of Earth!
Active Lecture Tips
1. Challenge your students to work in pairs to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species.
The Diversification of Mammals After the Extinction of Dinosaurs
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52
Mechanisms of Macroevolution: Large Effects from Small Genetic Changes
Scientists are increasingly able to explain the basic biological mechanisms of macroevolutionary changes seen in the fossil record.
Working at the interface of evolutionary biology and developmental biology (evo-devo) scientists are studying how slight changes in the flow of genetic information can become magnified into major structural differences among species.
Evolutionary transformations can result from genes that alter the rate, timing, and spatial pattern of changes in an organism’s form as it develops from a zygote into an adult.
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Student Misconceptions and Concerns
1. Clear examples of evolutionary remodeling include the many variations of the pattern of bones in the vertebrate forelimb. Bat wings, bird wings, penguin flippers, the arms of apes, and the digging forelimbs of moles all show how the ancestral pattern was revised as new functions evolved. Descent with modification is a powerful explanation of such diversity.
Teaching Tips
1. Another way to think about evolutionary remodeling is to make an analogy to remodeling a home. A remodeled home retains many of the “ancestral” traits—perhaps the same plumbing and electrical system. But where there once was a wall might now be an opening into an enlarged family room or a window to the outside.
2. When discussing exaptations, have students consider the many new uses for common household items if they were to have them in a survival situation, perhaps stranded along a highway or lost in the woods. A handkerchief, a screwdriver, and a pair of pliers might take on new functions in this different context.
3. Consider challenging your students to explain why evolution is not directional. Why is the evolution of a group not driven toward any ideal form or function? As a hint, you can ask them to describe the mechanisms by which variety arises in a species.
Active Lecture Tips
1. See the Activity Video Review: YouTube–Bang Goes the Theory: Evolution Made Simple at the Instructor Exchange in the MasteringBiology instructor resource area or at the following website: www.youtube.com/watch?v=YYLKt5J-KKY&noredirect=1
Comparison of Human and Chimpanzee Skull Development
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Identifying Major Themes (1 of 2)
In the course of giraffe evolution, increased growth rates during development produced extra-long (11-inch) neck vertebrae.
Which major theme is illustrated by this action?
The relationship of structure to function
Information flow
Pathways that transform energy and matter
Interactions within biological systems
Evolution
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Major Themes Answer—information flow
The Evolution of Biological Novelty: Adaptation of Old Structures for New Functions
The feathered flight of birds is a perfect marriage of structure and function. In flight, the shapes and arrangements of various feathers produce lift, smooth airflow, and help with steering and balance.
How did such an intricate structure evolve?
Thousands of fossils of feathered dinosaurs have been found and classified into more than 30 different species.
But the feathers seen in these fossils could not have been used for flight. Their reptilian anatomy was not suited to flying.
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Student Misconceptions and Concerns
1. Clear examples of evolutionary remodeling include the many variations of the pattern of bones in the vertebrate forelimb. Bat wings, bird wings, penguin flippers, the arms of apes, and the digging forelimbs of moles all show how the ancestral pattern was revised as new functions evolved. Descent with modification is a powerful explanation of such diversity.
Teaching Tips
1. Another way to think about evolutionary remodeling is to make an analogy to remodeling a home. A remodeled home retains many of the “ancestral” traits—perhaps the same plumbing and electrical system. But where there once was a wall might now be an opening into an enlarged family room or a window to the outside.
2. When discussing exaptations, have students consider the many new uses for common household items if they were to have them in a survival situation, perhaps stranded along a highway or lost in the woods. A handkerchief, a screwdriver, and a pair of pliers might take on new functions in this different context.
3. Consider challenging your students to explain why evolution is not directional. Why is the evolution of a group not driven toward any ideal form or function? As a hint, you can ask them to describe the mechanisms by which variety arises in a species.
Active Lecture Tips
1. See the Activity Video Review: YouTube–Bang Goes the Theory: Evolution Made Simple at the Instructor Exchange in the MasteringBiology instructor resource area or at the following website: www.youtube.com/watch?v=YYLKt5J-KKY&noredirect=1
An Extinct Bird
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Structure/Function: Adaptation of Old Structures for New Functions
The first utility of feathers may have been for insulation.
Once flight itself became an advantage, natural selection would have gradually remodeled feathers and wings to fit their additional function.
Structures such as feathers that evolve in one context but become co-opted for another function are called exaptations.
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Student Misconceptions and Concerns
1. Clear examples of evolutionary remodeling include the many variations of the pattern of bones in the vertebrate forelimb. Bat wings, bird wings, penguin flippers, the arms of apes, and the digging forelimbs of moles all show how the ancestral pattern was revised as new functions evolved. Descent with modification is a powerful explanation of such diversity.
Teaching Tips
1. Another way to think about evolutionary remodeling is to make an analogy to remodeling a home. A remodeled home retains many of the “ancestral” traits—perhaps the same plumbing and electrical system. But where there once was a wall might now be an opening into an enlarged family room or a window to the outside.
2. When discussing exaptations, have students consider the many new uses for common household items if they were to have them in a survival situation, perhaps stranded along a highway or lost in the woods. A handkerchief, a screwdriver, and a pair of pliers might take on new functions in this different context.
3. Consider challenging your students to explain why evolution is not directional. Why is the evolution of a group not driven toward any ideal form or function? As a hint, you can ask them to describe the mechanisms by which variety arises in a species.
Active Lecture Tips
1. See the Activity Video Review: YouTube–Bang Goes the Theory: Evolution Made Simple at the Instructor Exchange in the MasteringBiology instructor resource area or at the following website: www.youtube.com/watch?v=YYLKt5J-KKY&noredirect=1
Identifying Major Themes (2 of 2)
The thin membrane of skin stretched between the long “finger” bones of bats is an adaptation for flight.
Which major theme is illustrated by this action?
The relationship of structure to function
Information flow
Pathways that transform energy and matter
Interactions within biological systems
Evolution
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Major Themes Answer—the relationship of structure to function
From Simple to Complex Structures in Gradual Stages
Most complex structures have evolved in small steps from simpler versions having the same basic function, a process of refinement rather than the sudden appearance of complexity.
The evolution of complex eyes can be traced from a simple ancestral patch of photoreceptor cells through a series of incremental modifications that benefited their owners at each stage.
Checkpoint: Explain why the concept of exaptation does not imply that a structure evolves in anticipation of some future environmental change.
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Checkpoint response: Although an exaptation has new or additional functions in a new environment, it existed earlier because it worked as an adaptation to the old environment.
Student Misconceptions and Concerns
1. Clear examples of evolutionary remodeling include the many variations of the pattern of bones in the vertebrate forelimb. Bat wings, bird wings, penguin flippers, the arms of apes, and the digging forelimbs of moles all show how the ancestral pattern was revised as new functions evolved. Descent with modification is a powerful explanation of such diversity.
Teaching Tips
1. Another way to think about evolutionary remodeling is to make an analogy to remodeling a home. A remodeled home retains many of the “ancestral” traits—perhaps the same plumbing and electrical system. But where there once was a wall might now be an opening into an enlarged family room or a window to the outside.
2. When discussing exaptations, have students consider the many new uses for common household items if they were to have them in a survival situation, perhaps stranded along a highway or lost in the woods. A handkerchief, a screwdriver, and a pair of pliers might take on new functions in this different context.
3. Consider challenging your students to explain why evolution is not directional. Why is the evolution of a group not driven toward any ideal form or function? As a hint, you can ask them to describe the mechanisms by which variety arises in a species.
Active Lecture Tips
1. See the Activity Video Review: YouTube–Bang Goes the Theory: Evolution Made Simple at the Instructor Exchange in the MasteringBiology instructor resource area or at the following website: www.youtube.com/watch?v=YYLKt5J-KKY&noredirect=1
A Range of Eye Complexity Among Molluscs
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Classifying the Diversity of Life: Classification and Phylogeny
Taxonomy is the naming and classification of species.
Systematics includes taxonomy and focuses on
classifying organisms and
determining their evolutionary relationships.
Biologists use phylogenetic trees to
depict hypotheses about the evolutionary history of species and
reflect the hierarchical classification of groups nested within more inclusive groups.
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Student Misconceptions and Concerns
1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer.
2. Students may struggle with many aspects of phylogenetic trees. Students may not realize that each node/branch can be rotated to rearrange the groups without changing the nature of the relationships.
Teaching Tips
1. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity.
2. Homologous and analogous relationships can be confusing for students. Simple explanations and concrete examples can serve as guides to understanding each process. Homologous relationships reflect modifications of an ancestral form for many functions. Analogous relationships reflect modifications of many forms to a common function.
3. Genetic relationships provide one strong line of evidence for the ancestral relationships of life. Fossils, anatomy, embryology, and biogeography can also be used to test these same relationships. Remind students that scientists prefer to use multiple lines of evidence to test hypotheses such as phylogenies.
4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.
5. The National Center for Science Education is an organization working to support the teaching of evolution and defend it against sectarian attack. Its website, ncse.com, contains a great deal of useful information.
Active Lecture Tips
1. See the Activity Vertebrate Phylogeny on the Instructor Exchange. Visit the Instructor Exchange in the MasteringBiology instructor resource area for a description of this activity.
The Relationship of Classification and Phylogeny for Some Members of the Order Carnivora
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Classification and Phylogeny
Understanding phylogeny can have practical applications.
By constructing a phylogeny of maize, researchers have identified two species of wild grasses that may be maize’s closest living relatives.
The genomes of these plants may harbor alleles that offer disease resistance or other useful traits that could be transferred into cultivated maize, insurance against future disease outbreaks or other environmental changes that might threaten corn crops.
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Student Misconceptions and Concerns
1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer.
2. Students may struggle with many aspects of phylogenetic trees. Students may not realize that each node/branch can be rotated to rearrange the groups without changing the nature of the relationships.
Teaching Tips
1. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity.
2. Homologous and analogous relationships can be confusing for students. Simple explanations and concrete examples can serve as guides to understanding each process. Homologous relationships reflect modifications of an ancestral form for many functions. Analogous relationships reflect modifications of many forms to a common function.
3. Genetic relationships provide one strong line of evidence for the ancestral relationships of life. Fossils, anatomy, embryology, and biogeography can also be used to test these same relationships. Remind students that scientists prefer to use multiple lines of evidence to test hypotheses such as phylogenies.
4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.
5. The National Center for Science Education is an organization working to support the teaching of evolution and defend it against sectarian attack. Its website, ncse.com, contains a great deal of useful information.
Active Lecture Tips
1. See the Activity Vertebrate Phylogeny on the Instructor Exchange. Visit the Instructor Exchange in the MasteringBiology instructor resource area for a description of this activity.
Identifying Homologous Characters (1 of 2)
Homologous structures in different species may vary in form and function but exhibit fundamental similarities because they evolved from the same structure in a common ancestor.
Homologous structures are one of the best sources of information for phylogenetic relationships.
Convergent evolution involves superficially similar structures from different evolutionary branches that result from natural selection shaping analogous adaptations. Similarity due to convergence is called analogy, not homology.
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Student Misconceptions and Concerns
1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer.
2. Students may struggle with many aspects of phylogenetic trees. Students may not realize that each node/branch can be rotated to rearrange the groups without changing the nature of the relationships.
Teaching Tips
1. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity.
2. Homologous and analogous relationships can be confusing for students. Simple explanations and concrete examples can serve as guides to understanding each process. Homologous relationships reflect modifications of an ancestral form for many functions. Analogous relationships reflect modifications of many forms to a common function.
3. Genetic relationships provide one strong line of evidence for the ancestral relationships of life. Fossils, anatomy, embryology, and biogeography can also be used to test these same relationships. Remind students that scientists prefer to use multiple lines of evidence to test hypotheses such as phylogenies.
4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.
5. The National Center for Science Education is an organization working to support the teaching of evolution and defend it against sectarian attack. Its website, ncse.com, contains a great deal of useful information.
Active Lecture Tips
1. See the Activity Vertebrate Phylogeny on the Instructor Exchange. Visit the Instructor Exchange in the MasteringBiology instructor resource area for a description of this activity.
Identifying Homologous Characters (2 of 2)
Comparing the embryonic development of two species can often reveal homology that is not apparent in the mature structures.
If homology reflects common ancestry, then comparing the DNA sequences of organisms gets to the heart of their evolutionary relationships.
The more recently two species have branched from a common ancestor, the more similar their DNA sequences should be.
Some fossils are preserved in such a way that DNA fragments can be extracted for comparison with living organisms.
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Student Misconceptions and Concerns
1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer.
2. Students may struggle with many aspects of phylogenetic trees. Students may not realize that each node/branch can be rotated to rearrange the groups without changing the nature of the relationships.
Teaching Tips
1. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity.
2. Homologous and analogous relationships can be confusing for students. Simple explanations and concrete examples can serve as guides to understanding each process. Homologous relationships reflect modifications of an ancestral form for many functions. Analogous relationships reflect modifications of many forms to a common function.
3. Genetic relationships provide one strong line of evidence for the ancestral relationships of life. Fossils, anatomy, embryology, and biogeography can also be used to test these same relationships. Remind students that scientists prefer to use multiple lines of evidence to test hypotheses such as phylogenies.
4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.
5. The National Center for Science Education is an organization working to support the teaching of evolution and defend it against sectarian attack. Its website, ncse.com, contains a great deal of useful information.
Active Lecture Tips
1. See the Activity Vertebrate Phylogeny on the Instructor Exchange. Visit the Instructor Exchange in the MasteringBiology instructor resource area for a description of this activity.
Artist’s Reconstruction of Neanderthal
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Inferring Phylogeny from Homologous Characters (1 of 3)
In cladistics, organisms are grouped by common ancestry.
A clade consists of an ancestral species and all its evolutionary descendants and forms a distinct branch in the tree of life.
Thus, identifying clades makes it possible to construct classification schemes that reflect the branching pattern of evolution.
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Student Misconceptions and Concerns
1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer.
2. Students may struggle with many aspects of phylogenetic trees. Students may not realize that each node/branch can be rotated to rearrange the groups without changing the nature of the relationships.
Teaching Tips
1. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity.
2. Homologous and analogous relationships can be confusing for students. Simple explanations and concrete examples can serve as guides to understanding each process. Homologous relationships reflect modifications of an ancestral form for many functions. Analogous relationships reflect modifications of many forms to a common function.
3. Genetic relationships provide one strong line of evidence for the ancestral relationships of life. Fossils, anatomy, embryology, and biogeography can also be used to test these same relationships. Remind students that scientists prefer to use multiple lines of evidence to test hypotheses such as phylogenies.
4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.
5. The National Center for Science Education is an organization working to support the teaching of evolution and defend it against sectarian attack. Its website, ncse.com, contains a great deal of useful information.
Active Lecture Tips
1. See the Activity Vertebrate Phylogeny on the Instructor Exchange. Visit the Instructor Exchange in the MasteringBiology instructor resource area for a description of this activity.
Inferring Phylogeny from Homologous Characters (2 of 3)
Cladistics is based on the Darwinian concept of “descent with modification from a common ancestor.”
To identify clades, scientists compare an ingroup with an outgroup.
The ingroup is the group of species that is actually being analyzed.
The outgroup is a species or group of species known to have diverged before the lineage that contains the groups being studied.
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Student Misconceptions and Concerns
1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer.
2. Students may struggle with many aspects of phylogenetic trees. Students may not realize that each node/branch can be rotated to rearrange the groups without changing the nature of the relationships.
Teaching Tips
1. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity.
2. Homologous and analogous relationships can be confusing for students. Simple explanations and concrete examples can serve as guides to understanding each process. Homologous relationships reflect modifications of an ancestral form for many functions. Analogous relationships reflect modifications of many forms to a common function.
3. Genetic relationships provide one strong line of evidence for the ancestral relationships of life. Fossils, anatomy, embryology, and biogeography can also be used to test these same relationships. Remind students that scientists prefer to use multiple lines of evidence to test hypotheses such as phylogenies.
4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.
5. The National Center for Science Education is an organization working to support the teaching of evolution and defend it against sectarian attack. Its website, ncse.com, contains a great deal of useful information.
Active Lecture Tips
1. See the Activity Vertebrate Phylogeny on the Instructor Exchange. Visit the Instructor Exchange in the MasteringBiology instructor resource area for a description of this activity.
Simplified Example of Cladistics
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Inferring Phylogeny from Homologous Characters (3 of 3)
The cladistics approach to phylogeny clarifies evolutionary relationships that were not always apparent in other taxonomic classifications.
For instance, biologists traditionally placed birds and reptiles in separate classes of vertebrates.
An inventory of homologies indicates that birds and crocodiles make up one clade, and lizards and snakes form another.
If we go back as far as the ancestor that crocodiles share with lizards and snakes to make up a clade, then the class Reptilia must also include birds.
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Student Misconceptions and Concerns
1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer.
2. Students may struggle with many aspects of phylogenetic trees. Students may not realize that each node/branch can be rotated to rearrange the groups without changing the nature of the relationships.
Teaching Tips
1. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity.
2. Homologous and analogous relationships can be confusing for students. Simple explanations and concrete examples can serve as guides to understanding each process. Homologous relationships reflect modifications of an ancestral form for many functions. Analogous relationships reflect modifications of many forms to a common function.
3. Genetic relationships provide one strong line of evidence for the ancestral relationships of life. Fossils, anatomy, embryology, and biogeography can also be used to test these same relationships. Remind students that scientists prefer to use multiple lines of evidence to test hypotheses such as phylogenies.
4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.
5. The National Center for Science Education is an organization working to support the teaching of evolution and defend it against sectarian attack. Its website, ncse.com, contains a great deal of useful information.
Active Lecture Tips
1. See the Activity Vertebrate Phylogeny on the Instructor Exchange. Visit the Instructor Exchange in the MasteringBiology instructor resource area for a description of this activity.
How Cladistics is Shaking Phylogenetic Trees
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Classification: A Work in Progress (1 of 2)
Phylogenetic trees are hypotheses about evolutionary history.
Linnaeus divided all known forms of life between the plant and animal kingdoms. This two-kingdom system prevailed in biology for over 200 years.
In the mid-1900s, the two-kingdom system was replaced by a five-kingdom system that
placed all prokaryotes in one kingdom and
divided the eukaryotes among four other kingdoms.
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73
Student Misconceptions and Concerns
1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer.
2. Students may struggle with many aspects of phylogenetic trees. Students may not realize that each node/branch can be rotated to rearrange the groups without changing the nature of the relationships.
Teaching Tips
1. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity.
2. Homologous and analogous relationships can be confusing for students. Simple explanations and concrete examples can serve as guides to understanding each process. Homologous relationships reflect modifications of an ancestral form for many functions. Analogous relationships reflect modifications of many forms to a common function.
3. Genetic relationships provide one strong line of evidence for the ancestral relationships of life. Fossils, anatomy, embryology, and biogeography can also be used to test these same relationships. Remind students that scientists prefer to use multiple lines of evidence to test hypotheses such as phylogenies.
4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.
5. The National Center for Science Education is an organization working to support the teaching of evolution and defend it against sectarian attack. Its website, ncse.com, contains a great deal of useful information.
Active Lecture Tips
1. See the Activity Vertebrate Phylogeny on the Instructor Exchange. Visit the Instructor Exchange in the MasteringBiology instructor resource area for a description of this activity.
Classification: A Work in Progress (2 of 2)
In the late 20th century, molecular studies and cladistics led to the development of a three-domain system that consists of
two domains of prokaryotes (Bacteria and Archaea) and
one domain of eukaryotes (Eukarya).
The domain Eukarya is currently divided into kingdoms, but the exact number of kingdoms is still under debate.
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74
Student Misconceptions and Concerns
1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer.
2. Students may struggle with many aspects of phylogenetic trees. Students may not realize that each node/branch can be rotated to rearrange the groups without changing the nature of the relationships.
Teaching Tips
1. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity.
2. Homologous and analogous relationships can be confusing for students. Simple explanations and concrete examples can serve as guides to understanding each process. Homologous relationships reflect modifications of an ancestral form for many functions. Analogous relationships reflect modifications of many forms to a common function.
3. Genetic relationships provide one strong line of evidence for the ancestral relationships of life. Fossils, anatomy, embryology, and biogeography can also be used to test these same relationships. Remind students that scientists prefer to use multiple lines of evidence to test hypotheses such as phylogenies.
4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.
5. The National Center for Science Education is an organization working to support the teaching of evolution and defend it against sectarian attack. Its website, ncse.com, contains a great deal of useful information.
Active Lecture Tips
1. See the Activity Vertebrate Phylogeny on the Instructor Exchange. Visit the Instructor Exchange in the MasteringBiology instructor resource area for a description of this activity.
The Three-Domain Classification System
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Identifying Major Themes
Plants make their own organic matter from inorganic nutrients by photosynthesis.
Which major theme is illustrated by this action?
The relationship of structure to function
Information flow
Pathways that transform energy and matter
Interactions within biological systems
Evolution
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Major Themes Answer—pathways that transfer matter and energy
Evolution Connection: Evolution in the Anthropocene
The Anthropocene is a time of environmental change on an epic scale. Consequently, habitats affected by human impacts are natural laboratories for studying evolutionary adaptation.
Some organisms have become resistant to toxic pollutants from industrial processes.
Urban crested anoles in Puerto Rico have more sticky scales, an adaptation to slippery surfaces such as concrete and metal.
Urban blackbirds sing at a higher pitch, an adaptation that enables them to be heard over traffic noise.
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77
Student Misconceptions and Concerns
1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer.
2. Students may struggle with many aspects of phylogenetic trees. Students may not realize that each node/branch can be rotated to rearrange the groups without changing the nature of the relationships.
Teaching Tips
1. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity.
2. Homologous and analogous relationships can be confusing for students. Simple explanations and concrete examples can serve as guides to understanding each process. Homologous relationships reflect modifications of an ancestral form for many functions. Analogous relationships reflect modifications of many forms to a common function.
3. Genetic relationships provide one strong line of evidence for the ancestral relationships of life. Fossils, anatomy, embryology, and biogeography can also be used to test these same relationships. Remind students that scientists prefer to use multiple lines of evidence to test hypotheses such as phylogenies.
4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.
5. The National Center for Science Education is an organization working to support the teaching of evolution and defend it against sectarian attack. Its website, ncse.com, contains a great deal of useful information.
Active Lecture Tips
1. See the Activity Vertebrate Phylogeny on the Instructor Exchange. Visit the Instructor Exchange in the MasteringBiology instructor resource area for a description of this activity.
Urban-Adapted Animals
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Copyright
This work is protected by United States copyright laws and is provided solely for the use of instructors in teaching their courses and assessing student learning. Dissemination or sale of any part of this work (including on the World Wide Web) will destroy the integrity of the work and is not permitted. The work and materials from it should never be made available to students except by instructors using the accompanying text in their classes. All recipients of this work are expected to abide by these restrictions and to honor the intended pedagogical purposes and the needs of other instructors who rely on these materials.
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