750 -900 WORDS DUE BY SATURDAY!christel mae paddit

Important Events • 1738 - Linnaeus published his system of classification of

species. • 1795 - Hutton proposed the idea that the Earth was shaped

by gradual forces • 1796 - Cuvier published his theory that fossils were from

species that had become extinct • 1798 - Malthus' essay on the Principle of Population

published. • 1809 - Lamarck’s theory of evolution published - Darwin

born • 1830 - Lyell proposed his geological theory of

uniformitarianism. • 1831 - Darwin set out on the voyage of the Beagle • 1858 - Wallace wrote to Darwin setting out his theory of

natural selection. o Darwin's and Wallace's ideas were presented to the

Linnaean Society of London. • 1859 - Darwin published On the Origin of Species • 1865 - Mendel’s experiments on heredity published • 1953 – Watson and Crick (and Franklin!) discover the

structure of DNA • 1990 – 2003 – Human genome project

Charles Darwin (1809 – 1882) https://www.youtube.com/watch? v=K3QdmgEv7KE#t=105.943895

• Darwin was a naturalist and scientist from England in the 1800s. This was the time when it was being noticed that the world was very old and was constantly changing. Change over time is called evolution.

• Darwin sailed on a ship called the Beagle. He and his crew were on a five-year journey to map South America. Darwin also planned on collecting plant and animal species.

• Darwin’s theory of evolution explains the change of species over many (millions!) years.

Ideas that shaped Darwin’s thinking • Lamarck (late 1700s to early 1800s) proposed that species

changed to make themselves better in their environment. Example: a bird that walks in water will grow longer legs to accommodate searching for food. This would mean that the bird’s legs would gradually grow longer. This concept is called acquired characteristics.

o An individual doesn’t evolve, but a species (population) does.

• Lamarck also considered that the new traits would be passed to future generations, which is the concept inheritance of acquired traits.

•

https://steemitimages.com/p/3MxaK27PJLaXTye38LFsNXRdy NJyo2d31RaJSStdSLa6HAe? format=match&mode=fit&width=640

• This means that future generations of birds would have longer legs than their predecessors. He was incorrect in his assumption, as evolution (change over time) does not occur to make a species perfect. While incorrect, Lamarck’s work was helpful to Darwin - the connection between a species and its environment.

o Does a species evolve to become perfect? o We do evolve, not to become perfect, but to survive in

our current situation. o What is perfect?

• Malthus (late 1700s to 1800s) looked at populations and noticed that people were born faster than they were dying. Darwin saw that this applied to all organisms. The idea here is that if populations grow out of control (and never die) the world will be overpopulated. Which individuals survive? Which die?

• Mendel (mid to late 1800s): Mendel tested and explained laws that inform the transfer of genetic information from parent to offspring.

• Weisman (mid to late 1800s): The theory of germ cells (egg and sperm) and somatic cells (all other body cells) came from Weisman. This contributed to modern evolutionary synthesis as gametes (germ cells or egg and sperm cells) are the only source for natural selection.

• De Vries (late 1800s – early 1900s): He duplicated Mendel’s work while studying plant growth; he learned that different characters have different hereditary carriers. The term genes came from Darwin’s pangenesis.

• Lyell was a friend of Darwin. He emphasized natural law, which was that processes of the past were much the same as today. Earlier geologists explained events as acts of God. Lyell and Darwin explained processes as events caused by nature.

• These ideas and the work of others influenced thoughts on evolution. Darwin’s On the Origin of Species was published in 1859. Darwin’s work was a combination of his ideas, as well as the work of others (especially Malthus and Lamarck).

In his travels to different continents, he noticed patterns: Species vary globally (closely related but different environments)

o Darwin noticed that similar habitats in different parts of the world have similar animal species. For example, Darwin found flightless, ground-dwelling birds called rheas living in the grasslands of South America. Rheas look and act a lot like ostriches. Yet rheas live only in South America, and ostriches live only in Africa. When Darwin visited Australia’s grasslands, he found another large flightless bird, the emu.

• Natural selection would lead to the development of similar adaptations, even if the species are not closely related.

• Think: the growing habitat in Sask. is similar to Australia, which means plants are similar, even though on opposite ends of the world.

Species vary locally (similar environments but differences between species)

o Darwin noticed that different, yet related, animal species often occupied different habitats within a local area.

o He noted that the Galápagos Islands are close to the east coast of South America (considered ‘local’), yet they have different ecological conditions.

o The birds on the mainland are closely related to the birds on the Galapagos, however due to different selection pressures, the mainland birds are different from the island birds.

o Additionally, there are differences between the species that live in similar environments (ground finches,

o Remember...natural selection, so different adaptations would take place depending on the environment.

o Darwin proposed that birds on islands descended from birds in South America, although there were great differences because the environments were different.

o In addition, Darwin noticed several types of small brown birds on the islands with beaks of different shapes. He didn’t consider these smaller birds to be unusual or important—at first…

• Species vary over time

o Darwin also collected fossils, which are the preserved remains or traces of ancient organisms.

o Darwin noticed that some fossils of extinct animals were similar to living species.

o https://cdn.britannica.com/03/55003-050-FA859C9F/horses- dawn-horse-size-all-one-toes.jpg Putting the Pieces Together On the voyage home, Darwin thought about the patterns he had seen. Darwin sent plant and animal specimens to experts for identification. The Galápagos mockingbirds turned out to belong to three separate species found nowhere else. The little brown birds were actually all species of finches, also found nowhere else, though they resembled a South American finch species. The same was true of Galápagos tortoises, marine iguanas, and many plants that Darwin had collected on the islands. The evidence suggested that species are not fixed and that they could change by some natural process. Based on Darwin’s theory, organisms that are well adapted to their environment are able to survive and have offspring. In turn, the offspring likely carry the traits that will ensure their survival. We can trace this line back to common descent. Over time, a species would evolve, which Darwin called descent with modification, which meant that gradual change was occurring. The length of time – called deep time – allowed natural selection, since deep time is a concept of over 4 billion years Artificial Selection

• The concept of artificial selection is something that Darwin noticed among breeders and farmers. It was noticed that some trees produced more or bigger fruit and some cows gave more milk – nature provided the variation. It was also noticed that these traits were passed to the offspring. Even without knowledge of how traits were passed on, over time, selective breeding or artificial selection allowed humans to get more out of their plants and animals.

Natural Selection

• The struggle for existence is the concept organisms compete for food, water, living space, and other necessities. If one doesn’t get enough of these necessities, the organism will not survive to reproduce.

• Selection pressures lead to changes in the population as species with traits for fitness have advantages that support their ability to survive and reproduce.

• Darwin also noticed that there is variation in inheritable traits, and some inheritable traits make survival easier. Individual variation is the genotypic and phenotypic variation in species. While we all have genes for hair colour, due to individual variation different hair colours exist and are passed from one generation to the other.

o Genotype – the alleles of a particular trait ▪ You cannot ‘see’ genotype, you only see evidence

of it. ▪ B = bent pinky, b = straight pinky

Mom – Bb ​Dad – bb Kids have bb (phenotype shows straight pinkies)

o Phenotype – the expression of an allele in a species ▪ Physical representation of the trait (disclaimer: it is

not something that you can always see…. ▪ Finches = beaks, something that we can ‘see’ ▪ The evidence of the genotype

• A heritable trait that helps an organism survive in its environment is an adaptation. Adaptations can be physical (sharp claws to kill prey) or behavioural (ability to evade predators).

o Some finches had long toes and some had short toes o Round ears or pointy ears in a 13-lined chipmunk?

▪ Round or pointy ears is a heritable trait (it is inherited)

▪ Round or pointy ears have nothing to do with whether or not they survive, SO, these traits are NOT an adaptation!

o It’s the camouflage that ensures its survival o https://www.wildlifeillinois.org/wp- content/uploads/2019/03/Thirteen-Lined-Ground- SquirrelEDITED.jpg

• Survival of the fittest – since adaptation can affect the ability of a species to survive, fitness describes how well an organism can survive and reproduce in its environment. This means that an animal that has more adaptive traits is less likely to die and more likely able to produce offspring, and thus able to pass on those traits.

o If you are the fittest, or if you are fit, it means you have the adaptations to survive.

o An adaptation - the population or species adapts to their surroundings (to survive)

o A mutation – can be caused by a virus ▪ Mutations can occur randomly ▪ A mutation might have no effect on anything

(neutral) OR • A mutation can also lead to an adaptation.

▪ Some people have a mutated gene (heritable) that makes them resistant to HIV. Somehow…..a random mutation occurred that made this happen and this mutation is passed to offspring.

• The animals with low fitness are less able to survive, so tend to not produce offspring, and they die. This causes future generations to have more adaptive traits.

Normal is a subjective term. How do we decide what is normal? People accept something as a standard

​5 digits on our hands, 5 digits on our toes… As a society, we have decided that this is normal, therefore, anything that is not as above, is considered abnormal. Voldemort does NOT have a normal nose. Voldemort has an abnormal nose. BUT, what if…….everyone’s nose looked like Voldemort’s nose? Then he would have a normal nose. Normalcy is fluid….what is normal can change!! What is normal to one might not be normal to another. DNA is the master copy, lives in the nucleus of the cells, it is THE instruction manual; it CANNOT leave the nucleus. DNA tells our body to build proteins. The tools to build proteins (ribosomes et al) are in the cytoplasm mRNA is photocopy of the pages needed to build a specific Vaccine – mRNA is made for us, it is injected into our body, ribosomes read the mRNA and realize it is foreign and our body will mount an immune response, part of which involves memory cells. When the real virus comes along the body (snipers!) are ready​ Natural selection is the concept that organisms with the best traits are the ones that tend to survive. Natural selection is much like artificial selection except nature is selecting the best traits to ensure survival:

1) More offspring are born with the trait. 2) There is heritable variation in the population.

a. Nothing is perfect – a different natural event could make an adaptation useless.

3) Some individuals have the traits that makes them more likely to survive and reproduce.

Over time, populations evolved as they adapted to their environment. If the environment changes, the species (population) may adapt again. Evidence to support Darwin’s On the Origin of Species (1859) was difficult to find when his book was published, however, since then, advances in technology and increased research has brought evidence forth. Review Questions:

• Discuss how variations occur in a population. • Discuss the action of natural selection on individuals,

populations, and species • Explain how Darwin’s observations led to his inferences

about evolution. How Natural Selection Works Recall that fitness is one’s ability to survive and reproduce. The traits that favour fitness are those that favour natural selection. Individuals with high fitness have a greater chance of survival and reproduction than do those with low fitness, thus the offspring (likely) carry that fitness too. This means that the alleles (variations of genes) for those traits will be more common in a population. Single-gene

• Some traits are controlled by a single gene and others are controlled by more than one genes

• Single-gene traits are controlled by one gene and may have just two of three phenotypes (appearances).

• Ex: in a particular snail, one gene controls the stripes on the shell (Or, there are two alleles (variations) in snails for shell shape

• https://www.agric.wa.gov.au/grains/identification-and-control-pest- slugs-and-snails-broadacre-crops-western-australia?nopaging=1 • https://1mkturin.files.wordpress.com/2008/09/snails001.jpg

• With single-gene traits, natural selection can lead to changes in

allele frequency (how often it appears in a population). Over time, if one trait survives better than another, that allele (particular gene) will become more common in the population.

Polygenic Traits

• Polygenic traits are controlled by more than one gene and have many genotypes and phenotypes.

• Polygenic traits produce a range of phenotypes (skin colour, eye colour, or height, for example), and the range is typically shown in a bell curve. The shape of the curve changes depending on where the higher fitness is.

• The number of phenotypes for a trait depends on the number of genes that control it (more variations = more genes)

• Height is a polygenic trait, and if you graphed the height of a population, you would see a bell-curve, which is typical for polygenic traits.

•

https://slideplayer.com/slide/5266066/17/images/14/Polyg enic+Inheritance.jpg

• Skin colour is also polygenic: • https://sites.google.com/a/canacad.ac.jp/hl2-biology- ferguson/_/rsrc/1470268831126/08-genetics/10-3- polygenic-inheritance/489071.jpg • If the fitness trait is at one end of the curve, directional

selection will take place (ex: birds with bigger beaks – since the birds with the bigger beaks will survive, over time, the average size of the beaks will increase, which will shift the curve.)

• If natural selection favours the average trait, then the curve will gradually peak in the middle. This is stabilizing selection. An example of this is the size of babies – smaller babies have more difficulties in surviving and larger babies have more troubled deliveries.

• In disruptive selection, the extremes are more likely to survive and reproduce, which shifts the graph in an odd manner. Example – beak size: if seeds are small or large then there will be a decrease in the number of birds with ‘average’ beak size.

Other Evidence of Evolution Convergent evolution: is seen in different species that have similar traits or characteristics that have developed (evolved) due to selection pressures. There is no common ancestor with respect to the trait, however. As seen in the picture below, the arctic wolf and the ptarmigan are similar in colour and fluffiness, both of which are traits for survival. These two are not closely related, on an evolutionary tree, yet have recognizable similarities. This is evidence of natural selection.

Image credit: Evidence for evolution. (n.d.). Kahn Academy. https://www.khanacademy.org/science/ap-biology/natural- selection/common-ancestry-and-continuing- evolution/a/evidence-for-evolution

Analogous structures indicate convergent evolution: • Not closely related on the evolutionary tree; different structure

but similar function • https://s3-us-west-2.amazonaws.com/courses-images/wp- content/uploads/sites/1842/2017/05/26155634/figure-20-02- 02.jpeg Divergent evolution is seen with species that come from a common ancestor but continue to evolve independently (due to selection pressures). Practical examples of this are seen with homologous structures, such that the similarity in structure speaks to a common ancestor, but clearly the function is not at all similar. Divergent evolution is evidence of a common ancestor. Homologous structures indicate divergent evolution:

• close on the evolutionary tree; similar structure but different function

• https://pixfeeds.com/images/32/609061/1280-homologous- forelimb-structure.png

Adaptive radiation is an example of divergent evolution in that there is one ancestral species. Darwin’s finches illustrate this as there are many similarities among the different finch species, which indicates a common ancestor, but each finch species has adapted to survive and reproduce in its habitat.

Image credit: Adaptive radiation. (n.d.). BioNinja. https://ib.bioninja.com.au/standard-level/topic-5-evolution- and-biodi/52-natural-selection/adaptive-radiation.html

Embryology: during fetal development, it was noted that not even a trained scientist could tell the species of the fetus at its early stages. The fact that there is great similarity in fetal development is further evidence of common ancestry.

Note: Sauropsids are egg-laying vertebrates Image credit: Examples of homologous structures that reveal our shared ancestry.

(n.d.) BiologyWise. https://biologywise.com/examples-of-homologous- structures

Vestigial structures are those that have no important function, although the presence of them indicates a connection to common descent. •

https://sites.google.com/site/brandtevolution/_/rsrc/1418361509 106/home/mutation/Vestigial%20Structures.jpg? height=598&width=1005 • https://qph.fs.quoracdn.net/main-qimg- f3b64a949804cc368befad068f390b92.webp

Natural Selection: crash course

https://www.youtube.com/watch?v=aTftyFboC_M Factors the Affect Populations Gene Flow Gene flow refers to the ‘movement’ of genes in a population due to reproductive processes.

Sexual Reproduction Since sexual reproduction combines the genetics of two parents, there are millions of possible genetic combinations. Crossing- over makes the possible combinations even greater. So sexual reproduction does change the outcome (think: appearance) but it does not change the frequency of genes in a population. Think of a deck of cards…you can shuffle the cards and be dealt a different hand each time, but there are still 52 cards in the deck… Genetic Drift Definition: variation in the relative frequency of different genotypes in a small population, owing to the chance disappearance of particular genes as individuals die or do not reproduce. In small populations, chance events can cause evolution, not natural selection. Genetic drift is a random change in allele frequency. There are two types of genetic drift: Genetic Bottlenecks

• If, for example, a disaster kills most of a population and the surviving organisms have a set of alleles that was different from the entire population. When this population grows, the unique trait will become the principle trait. This effect can greatly reduce genetic diversity.

The Founder Effect • This occurs when a few individuals move into a new habitat.

If the small group has a set of alleles that is different from the original population, a new allele is introduced.

• If a small group moves out of a population, specific alleles will become prevalent in the newer, smaller population.

Summary Mutation causes a phenotypic change. The mutation creates a different allele, which will then be passed to future generations

Founder effect – a new member, with different alleles moves into a population, resulting in the new allele(s) being introduced into the population.

Genetic drift – a chance event takes some alleles out of the population.

Natural selection – if one phenotype is selected over another, the allele frequency will change

Image credits: Understanding evolution. (n.d.). University of California Museum of Paleontology's http://evolution.berkeley.edu

Speciation - the formation of a new species Crash Course video: https://www.youtube.com/watch? v=2oKlKmrbLoU Examples of speciation

• There are finches present on the Galapagos Islands. When founders arrive they will introduce new alleles to the population.

• Since finches tend not to fly over water (how they got to the island…by chance…), they will be geographically separated from where they first came. On the island, natural selection would lead to a new population of finches that was different from the first.

• As time goes on, directional selection will reflect the prevailing alleles (beak size, for example).

• Behaviourally – if finches from the island population returned to their original home, their behaviours would be so different from the finches that were still there (originally…), the two different species would not interbreed. This would lead to different species of finches.

Competition and Evolution

• Sexual competition – mates are selected by determining which has the best characteristics

• Resource partitioning – similar species are competing for the same resources (such as food). The better competitor wins - this requires having the adaptive trait - those with the ‘best beak’ would survive and reproduce. Resource partitioning includes other factors (shelter, for example).

When species breed, this connects their gene pools, but if the species split, genetic changes in one do not affect the other.

https://www.youtube.com/watch?v=2oKlKmrbLoU&t=17s

Isolating Mechanisms Isolating mechanisms are those that cause species to separate from each other. If species are separated and kept apart, genetic differences develop. Even if the two species meet again, they won’t reproduce. The result is that you have two different species. If this continues to happen, you can end up with many different species of the same animal, perhaps 13different finch species! Reproductive isolation occurs when two populations can no longer mate. There are different ways species can become reproductively isolated from each other:

• Geographic isolation – the species is physically separated from the other. This is allopatric speciation. If the members of the population evolve in the absence of geographic isolation, this is sympatric speciation.

Image credit: University of California Museum of Paleontology's Understanding Evolution (http://evolution.berkeley.edu).

• Sympatric speciation – the individuals are not geographically isolated (they are in the same location) so there is something else that causes isolation.

o Behavioural isolation – if the behaviour of the species causes them not to mix, then breeding won’t happen. For example, if one species changes its mating song, the others won’t respond to it.

o Temporal isolation – if reproductive schedules differ, the species won’t interbreed.

Rate of Evolution • Evolution of all species does not happen at the same rate. If

there is no change in the population, it will be in equilibrium ((think: the deck of cards is just shuffling…no cards are leaving or being added). Two explanations for evolutionary rate (evolutionary change in a population) are gradualism and punctuated equilibrium.

• Gradualism o This is slow and steady evolution that occurred over many

years. Fossil records supported this. • Punctuated equilibrium

o Some species have shown no evolution at all, which means the species is in equilibrium. Punctuated equilibrium is a rapid change of that equilibrium (which can still take thousands of years!)

• Rapid change after equilibrium can affect small populations by genetic changes that happen among fewer individuals. This might also happen when a species moves to a new environment (Darwin’s finches!). Mass extinctions can also lead to rapid change among the remaining species.

o http://lh2015bio11.weebly.com/uploads/1/3/7/9/13790835/1445760_ orig.gif

History of Life • Fossil records are valuable for giving us information about the

history of life on earth. • Most fossils are the preserved remains of living organisms. The

hard parts of the body are preserved; the soft parts (muscle tissue, skin...) typically rot or are eaten. Fossils can be as large as a whole animal or as small as a bone or a tooth. Trace fossils are those that give signs of activity, such as droppings, footprints, burrows.

Without fossils, we would not have information about species that have become extinct. Fossils can show:

• How an organism lived • What an organism ate • How an animal moved (bone structure, footprints) • The nature of the habitat – leaves, pollen, for example – can tell

us about the area (swamp? Forest?) • Ecosystems – when plants and animals are fossilized together.

Life on a Changing Planet

• These can form mountain ranges and move continents. Plate tectonics is the theory that the surface of the earth sits on plates and these plates have moved (slowly). They continue to move, which causes natural disasters, such as earthquakes and volcanoes.

• We know that Africa and South America are separated by the Atlantic Ocean, but fossils of the same reptile, Mesosaurus, found on both continents, are reason to believe that these continents were once connected.

• Earth’s climate has changed over time, and many of these are caused by small changes in temperature. Small temperature changes can make big differences.

• Comets and asteroids - large objects from space have crashed into earth several times, which may have caused the sun to be blocked. This would cause cooling, which could then have caused organisms to become extinct.

• Living organisms provide lots of information about the age of the earth. Plants take in carbon, which, over time, can affect climate (cause cooling).

• Since changing environments has caused species to adapt, we see new species and extinction. Extinction occurs when all members of a species die without reproducing. Speciation is the evolvement of new species.

• Genetic variation increases survival in a changing environment, • Background extinction occurs slow and steady and occurs over

long periods of time. Mass extinction occurs in a short period and can cause entire ecosystems to disappear. Mass extinctions are usually due to natural disasters.

• Rapid change after equilibrium can affect small populations by genetic changes that happen among fewer individuals. This might also happen when a species moves to a new environment (Darwin’s finches!). Mass extinctions can also lead to rapid change among the remaining species.

Gene flow can occur when an individual travels from one geographic location to another and joins a different population of the species. In the example shown here, the brown allele is introduced into the green population.

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