Lesson: The "We" in Evolution: Biological Collectivism
Computer with internet access, preferably computers for each student
Biology- Evolution 8. Evolution is the result of genetic changes that occur in constantly changing environments.
Ask students what causes populations to survive, thrive, and increase. What causes them to die out or decrease? List the factors they come up with on the board and encourage students to consider different types of populations, such as bacteria, sea plants, fish, people, trees, etc.
Using a dialogue approach, ask students to dig deeper into explanations as you write them on the board. Encourage students to take notes, as they will apply this knowledge to games that simulate natural selection and evolution.
What are factors that will increase a population? If there are more resources, like more to eat, then more of the population will survive and reproduce.
What are factors that will decrease a population? If there are many of a population, its predators will have more to consume, so more of the predators will survive and reproduce. This will cause them to kill off more of the original population. If there are too many of a population, they will use up their resources more quickly. When there are fewer resources, fewer of the population will survive and reproduce.
Can a population keep increasing forever/without limit?
No, because there will only be so much food, space, water, and other resources for them to use. Once there are too many plants/animals for the resources, some will die off.
Does it hurt a population to be too dense (a thick population in one area)?
Yes, when there are too many living close together, it is easier for disease to spread. In animals, some will have to take poor-quality territory, and then they won’t reproduce as well because those areas will have fewer resources.
How do mutations and adaptations affect the population? If some members of a population are better able to survive, they are more likely to reproduce. When the population is pressured to decrease, these members are likely to survive longer and reproduce. They will then be a larger portion of the surviving members. If a mutation makes members less able to survive, they will be more likely to die out as soon as the population is pressured.
More information or independent reading here: http://www.nature.com/scitable/knowledge/library/population-limiting-factors-17059572
Guide students through this game as a class. http://www.abpischools.org.uk/page/modules/population_growth/activity.cfm?age=Age%20Range%207-11&subject=science
First, run the simulation on normal, and have students write down the total number of rabbit in the population. Then, ask for student predictions about how adjusting the conditions will affect the populations. For each adjustment, brainstorm a mutation that would turn out to be a helpful adaptation to these conditions. For instance, if you lower the food, you might anticipate that rabbits with lower metabolism will outlast others, and thus may shift the genetic features of the population. Repeat for the scenarios with bacteria, etc. Discuss how this applies to the use and overuse of antibiotics. (Discuss drug-resistancy in general.)
If you don’t have computer/internet access, you can build a similar lesson around this whole class game: http://lawrencehallofscience.org/gss/uptodate/articles-gss/8pg200404popgame.html
This is the best game yet! Have students play this game on computers to see evolution through the eyes of Darwin. They should also explore the quiz and the bio.
Have students take the quiz on Darwin. If you don’t have enough computers, you can do this as a class.
Remind students that nature, although we like to talk about it as a thing or a person, is never “acting” with a plan. Everything happens in cause and effect patterns, but no outcomes can be guaranteed or selected unless humans interfere. (An example is dog breeding, where we like to help dogs reproduce because they’re cute, even if they wouldn’t have survived in the wild.) Understanding this, we still see the general patterns of how things turn out, so we sum up evolution as “survival of the fittest.” Write this phrase on the board. Ask students to decide and explain whether this “philosophy” of nature is more individualist or more collectivist. Write this question on the board. Encourage justifications. You may do this as a short written reflection, a pair share, or a discussion.