1. In this lab, we simulated a population of organisms competing for survival. We wanted to model the process of natural selection. There were 3 phenotypes for picking up food in our environment: stumpys (AA), knucklers (Aa), and pinchers (aa). Corks represented food, and the food was scattered around a field. The organisms had 30 seconds to gather as much food as they could, and they had to get a certain amount in order to mate and reproduce.
2. Pinchers were the best phenotype at gathering food, because they got to pick up food with their thumb and their index finger, which was the easiest to get as much food as possible.
3. We found that the population did evolve, and the changed allele frequency is evidence for that. In the initial population, the frequency of the "A" allele was 52% and the frequency of the "a" allele was 48%. After 8 generations, the "A" allele frequency was 41% and the "a" allele frequency was 59%.
4. The genotypes and phenotypes that each organism was "born with" was completely random, the scattering of food throughout the field was random.
5. If the food supply was smaller than it was, there would have been more competition within the population for food. In this situation, the more aggressive organisms would have obtained more food regardless of their food-gathering phenotype. If there was a larger food supply, those organisms who weren't as aggressive would have a more equal chance. This parallels what happens in nature when food is scarce.
6. The results would probably have been significantly different if there was no incomplete dominance with the knucklers. The "A" allele would probably have been completely wiped out, because the stumpys' phenotype was the most difficult for gathering food.
7. In natural selection, nature "favors" individuals who have the best traits. The population evolves to look like these individuals.
8. At times when the food supply was clumped, some individuals developed aggressiveness in order to gather enough food and survive. There are many behaviors similar to this in nature, when an animal is more skilled at gathering food fast, or running from a predator. Individuals needed a place to store their food after they picked it up, and those with bigger pockets often had an advantage. In nature, certain animals will have certain genetic advantages like this over other organisms. The individuals with these strategies' phenotypes would have been more common in the population, which affects the allele frequency.
9. In nature, natural selection acts on and favors certain phenotypes, not genotypes. Populations as a whole will evolve, but not individuals.
10. One question I still have from this lab is: in nature, how much of an organism's chance of survival has to do with it's genes and how much has to do with it's learned skill set?
Good question. It's hard to quantify that but you're right that both play a role. Consider this: Individuals who teach their offspring how to survive are more likely to survive, and so really natural selection favors both phenotypes and behaviors. The real question is: How much of a genetic influence is there on that?
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