Summary
Students will observe that random mutations in a organism's genes combined with a competitive environment lead to the evolution of a well-adapted organism.
Implementation
To Students: Today we are going to learn about a new part of the game. In the past, when an organism reproduced, it created an organism with the exact same genes that it had. However, in nature, organisms sometimes create offspring that have genes that are different than the parent's genes. How does this happen? Sometimes when your body makes copies of its genes to pass on to its offspring, the body makes a mistake in copying. Other times, environmental factors (such as radiation, viruses, or other chemicals) can cause genes to change slightly. These changes in genes are called "mutations."
You may have noticed the mutation check box in the lower right hand corner of the game. If you click that box, every organism will now have a very small chance of passing on mutated genes to its offspring. The mutated genes are very close to the original genes, but are slightly off. For example, if an organism's genes were 50 search, 50 gather, and 50 reproduction, it's offspring's genes may be 49 search, 51 gather, and 50 reproduction.
Let's explore this option. I am going to place 20 organisms in the world.
Teacher: Select "Jungle" from the scenarios menu. Add 20 organisms, with 50 search, 50 gather, and 50 reproduction. Check the mutation checkbox. Advance 1k turns so students can see that a few organisms mutate after several turns.
To Students: What do you think will happen if I run this for 200k turns? (The answer is that the genes will slowly drift towards what is adaptive in the jungle. To be specific, the genes of the multiple organisms should resemble something like this:
200k turns: 48 Search, 41 Gather, 60 Reproduce
Why do you think the genes moved more towards reproduce?)
Teacher: Now progress 200k turns several times and observe the results Your results should look something like this:
400k turns: 25 Search, 32 Gather, 91 Reproduce
600k turns: 24 Search, 26 Gather, 98 Reproduce
800k turns: 24 Search, 34 Gather, 91 Reproduce
To Students: Why do you think the genes ended up how they are? What did you notice at the end? (The genes seemed to hover around the same numbers after 400k turns). Why do you think the genes hovered after a certain period of time? (because the genes had reached an adaptive ratio and could not improve anymore). What is necessary for evolution? What factors do we have here that drive the organisms to evolve? (Answer: Reproducing Organisms, mutations, and a competitive environment (one with limited resources).
Now let's try the same thing in a different scenario. (Select "Grasslands" from the scenarios menu) Add 20 organisms with 50 search, 50 gather, and 50 reproduction.) What do you think will happen if we advance 200k turns, 400k turns, or 800k turns?
(After 800k turns, you should end up with an organism like this: 53 Search, 36 Gather, and 60 Reproduction) Why do you think the organisms ended up differently than the organisms in the jungle? (The answer is that the grasslands environment is different, so different genes are adaptive here. In the grasslands, less food is dropped per turn. Therefore, unlike in the jungle, the organisms cannot spend a ton of resources reproducing. If it did, it would starve too quickly. In the plains, the organisms must spend the most time searching because there is limited food. The students should understand from this experiment that organisms acquire different adaptations for their environments. A good real life example of adaptation is seen in rabbits. The arctic hare has a white coat so it can blend in with its snowy, arctic environment. A jackrabbit, on the other hand, has evolved to have a brown coat so that it blends in with the dessert. Encourage students to offer other examples of adaptations.)
Links
Mutation
Adaptation