LAB 3
Biodiversity, short for biological diversity, includes the genetic variation between all organisms, species, and populations, and all of their complex communities and ecosystems. It also reflects the interrelatedness of genes, species, and ecosystems and their interactions with the environment. Biodiversity is not evenly distributed across the globe; rather, it varies greatly, even within regions. It is partially regulated by climate - for example, tropical regions can support more species than polar climates. In whole, biodiversity represents variation within three levels: Species diversity Ecosystem diversity Genetic diversity
It should be noted that diversity at one of these levels may not correspond with diversity within other levels. The degree of biodiversity, and thus the health of an ecosystem, is impacted when any part of that ecosystem becomes endangered or extinct.
The term species refers to a group of similar organisms that reproduce among themselves. Species diversity refers to the variation within and between populations of species, as well as between different species. Sexual reproduction critically contributes to the variation within species. For example, a pea plant that is cross-fertilized with another pea plant can produce offspring with four different looks! This genetic mixing creates the diversity seen today.
Ecosystem diversity examines the different habitats, biological communities, and ecological processes in the biosphere, as well as variation within an individual ecosystem. The differences in rainforests and deserts represent the variation between ecosystems. The physical characteristics that determine ecosystem diversity are complex, and include biotic and abiotic factors.
Concepts to Explore
Biodiversity Species diversity
Ecosystem diversity
Genetic diversity Natural selection
Extinction
Figure 1: There are more than 32,000 species of fish – more than any other vertebrate!
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The variation of genes within individual organisms is genetic diversity. This can be measured within and between species. It plays an important role in survival and adaptability of organisms to changing environments.
Diversity is also influenced by natural selection, the key mechanism of evolution. The process of natural selection describes competition between individual species for resources, such as food and space (habitat). Genetic variations among species provide an advantage over other species if those variations result in the ability to survive and reproduce more effectively.
Evidence that supports the theory of natural selection includes the fossil record of change in earlier species, the chemical and anatomical similarities of related life forms, the geographical distribution of related species, and the recorded genetic changes in living organisms over many generations. Take for example, homologous structures among different species, such as the wing of a bird and the forearm of a human. These structures provide evidence that embryologically similar structures can give rise to different functions based on the needs of the organism. Note that natural selection does not try to explain the origin of life, but rather the later evolution of organisms over time.
Biodiversity is important to the process of evolution because it provides the framework on top of which natural selection can occur. As discussed above, natural selection determines genetic fitness, an organism's genetic contribution to the next generation. Natural selection occurs by selecting one trait as "more advantageous" in a certain environment. The root of this selection is biodiversity.
Species extinction is not new; species have been evolving and dying out since life began. Now, however, species extinction is occurring at an alarming rate, almost entirely as a direct result of human activity. Scientists recognize five major mass extinctions in the Earth’s history. Extinctions are measured in terms of large groups of related species, called families. The five mass extinction episodes occurred because of major changes in the prevailing ecological conditions brought about by climate change, cataclysmic volcanic eruptions, or collisions with giant meteors. The sixth mass extinction appears to be in progress now, and the primary cause is environmental change brought about by human activity. Some examples of species on the “endangered” list are the ivory billed woodpecker, amur leopard, javan rhinoceros, northern great whale, mountain gorilla, and the leatherback sea turtle.
? Did You Know...
A present day example of natural selection can be seen in the crayfish population. The British crayfish are crustaceans that live in rivers in England. The American crayfish was introduced to the same bodies of water that were already populated by the British crayfish. The American crayfish are larger, more aggressive and carry an infection that kills British crayfish but to which they are immune. As a result, the British crayfish are decreasing in number and are expected to become extinct in Britain within the next 50 years. Thus, the American crayfish have a genetic variation that gives them an advantage over the British crayfish to survive and reproduce.
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Loss of an individual species can have various effects on the remaining species in an ecosystem. These effects depend upon the importance of the species within the ecosystem. Individual species and ecosystems have evolved over millions of years into a complex interdependence. If you remove enough of the key species on which the framework is based, then the whole ecosystem may be in danger of collapsing. Regardless of a species’ place in the ecosystem, it is important for humans to take care of the world around us. As people become more aware of how their actions impact all living things, they can make adjustments in an effort to preserve life on all levels.
There are many activities that humans take part in that impact the environment and biodiversity. The exhaust from automobile and aircraft travel, as well as smoke stacks from industrial plants, are the leading causes of air pollution, which can have harmful effects on natural resources and organisms. Two other important factors that can have an effect on biodiversity are overpopulation and affluence. Overpopulation means that there are more people than resources to meet their needs. As people become more affluent, there is an increase in per capita resource utilization. All of these factors contribute to overharvesting, habitat degradation, and increased pollution, which threaten biodiversity.
Figure 2: The amur leopard is at risk of extinction.
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Experiment 1: Effects of Water Pollution on Plant Diversity Water pollution can have severely negative effects on biodiversity and ecosystems, particularly on plant populations. In many cases, these pollutants are introduced to the environment through everyday human activity. In this experiment, you will contaminate several water samples, as well as purify a water sample. You will then evaluate the effects of water pollution and purification on the biodiversity of wildflowers. Materials
(8) 250 mL Beakers
(2) 100 mL Beaker
Permanent marker 4 Wooden stir sticks
100 mL Graduated cylinder 10 mL Graduated cylinder
10 mL Vegetable oil
10 mL Vinegar
10 mL Liquid laundry detergent
40 mL Sand
20 mL Activated carbon
60 mL Gravel
Alum
Potting Soil
Seed Mixture (Zinnia, Marigold, Morning Glory, Cosmos, and Ryegrass)
(3) 5.5 X 3.5 in. Peat pots
Funnel
Cheesecloth
Bleach
*Stopwatch (Phone or Internet) *Scissors
*2 Clean, empty water or soda bottles (must hold at least 500 mL)
*Water
*Camera/Smart Phone
*You must provide
Procedure Part 1: Water Contamination 1. Obtain the eight 250 mL beakers. Use the permanent marker to label the beakers 1 - 8.
2. Set Beakers 5 - 8 aside. Fill Beakers 1 - 4 with 100 mL of water using your 100 mL graduated cylinder. 3. Record your observations of the water in Beaker 1 in Table 1. Remember to use a safe wafting technique to smell the solutions (see the Appendix for instructions).
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4. Add 10 mL of vegetable oil to Beaker 2. Mix thoroughly with a wooden stir stick. Record your observations of the water in Beaker 2 in Table 1. (Don’t forget to wash the graduated cylinder between use!) 5. Add 10 mL vinegar to Beaker 3. Mix thoroughly with a wooden stir stick. Record your observations of the water in Beaker 3 in Table 1. 6. Add 10 mL of liquid laundry detergent to Beaker 4. Mix thoroughly with a wooden stir stick. Record your observations of the water in Beaker 4 in Table 1. 7. Cut your piece of cheesecloth into five different pieces (reserve one piece for the water purification portion of this experiment). Fold one piece of the cheesecloth so that you have a piece 4 layers thick and big enough to line the funnel. Place it inside the funnel. 8. Measure 60 mL of soil using the 100 mL beaker and place it into the cheesecloth-lined funnel.
9. Place the funnel inside Beaker 5.
10. Pour the contents of Beaker 1 (water) through the funnel so that it filters into Beaker 5 for one minute. Record your observations of the filtered water in the Beaker 5 row of Table 1.
11. Discard the cheesecloth and soil from the funnel.
12. Repeat Steps 8 - 11 for Beakers 2, 3, and 4. (Filter the contents of Beaker 2 into Beaker 6, the contents of Beaker 3 into Beaker 7, and the contents of Beaker 4 into Beaker 8). Record your observations for each sample in the rows for Beaker 6, 7, and 8 in Table 1. 13. Wash the funnel and place it in the top of a clean, empty water or soda bottle. Pour the four contaminated water samples from beakers 5 - 8 into the bottle. Save the water in the bottle - you will need this for later in the experiment! 14. Thoroughly wash all of the beakers for use in the next part of the experiment.
Part 2: Water Purification 15. Add 100 mL of soil to a clean 250 mL beaker. Fill to the 200 mL mark with water. 16. Pour the water and soil solution back and forth between two 250 mL beakers 15 times. 17. After the water and soil have been mixed, pour 10 mL into a clean 100 mL beaker. You now have two samples of "contaminated" water. The "contaminated" water that remains in the 250 mL beaker will be used for the purification process and will be "treated." Save the "contaminated" water in the 100 mL beaker for the end of the experiment so you can compare it to the "treated" water after the filtration process.
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18. Add 10 grams of alum (all of the contents in the bag you have been given) to the 250 mL beaker containing the “contaminated” water. Slowly stir the mixture with a wooden stir stick for 1 - 2 minutes. Let the solution sit for 15 minutes.
19. In the meantime, place the funnel into a clean 250 mL beaker. Fold a piece of cheesecloth so that you have a piece 4 layers thick that is big enough to line the funnel. Place it inside the funnel.
20. Begin layering the funnel, starting by pouring 40 mL of sand into the cheesecloth-lined funnel, then 20 mL activated charcoal, then 40 mL gravel. Use a 100 mL beaker to measure these amounts. 21. To solidify the filter, slowly pour clean tap water through the filter until the funnel is full. Discard the rinse water from the beaker and repeat four more times. Return the funnel to the top of the beaker and let sit for 5 minutes before emptying the beaker and continuing the experiment. 22. After 15 minutes have passed, pour about 3/4 of the “contaminated” water into the funnel, without mixing the up the current sediment. Let it filter through the funnel into the beaker for 5 minutes.
23. Note the smell of the filtered water, comparing it to the 10 mL sample taken from the mixture in Step 3.
24. Remove the filter from the beaker. Use the 10 mL graduated cylinder to measure approximately 10 mL of the water. Pour it into a clean 100 mL beaker and add a few drops of bleach solution to the filtered water within the beaker. Stir the water and bleach combination slowly for about 1 minute. Note: DO NOT discard the rest of the water in the 250 mL beaker. You will store this water for later in the experiment.
25. The “contaminated” water has now been filtered. Compare the newly created “treated” water with the 10 mL sample of the initial “contaminated” water and answer post-lab questions 3 and 4.
26. Discard the cheesecloth containing the filter and wash the funnel. Place the funnel in the top of a clean, empty water or soda bottle. Pour the purified water into the bottle. Then, use a 100 mL graduated cylinder to add 150 mL of tap water to the bottle. Save the water in the bottle - you will need this for later in the experiment.
Part 3: Evaluating the Effects of Water Pollution on Plant Diversity 27. Now, take a moment to hypothesize how polluted or purified water might affect plant growth and plant diversity. Record your hypothesis in post-lab question 5.
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28. Obtain three pots from your kit and label them “Tap Water,” “Contaminated Water,” and “Purified Water.” Fill them loosely with soil until it is approximately 1 inch from the top.
29. Pour approximately 40 mL of tap water into your pots (less if the soil becomes very wet). 30. Lightly scatter your seeds on top of the soil in each container. Add an approximately equal number of seeds to each pot. There should be a random assignment of seeds to the pots.
31. Press each seed down about ½ inch into the soil. 32. Place the pots in a sunny, indoor location. Observe and water the seeds daily with tap water, and the contaminated water and purified water you saved in parts 1 and 2. These seeds will germinate quickly (3- 7 days).
33. Complete Table 2 approximately 1 - 2 weeks (or when you see a reasonable amount of plant growth in the peat pots). To indicate whether a plant has germinated or not, circle yes (Y) or no (N). Table 3 provides pictures of the germinated seeds to help you determine when you should begin entering data, and what each plant looks like.