Hunger Games Lab

In this lab we simulated different phenotypes of a population competing for food. The different phenotypes were "stumpy," "knuckler," and "pincher." The stumpy phenotypes could only pick up food with its wrists, the knuckler could only pick up food with the knuckles of its first and second fingers, and the pincher could only pick up food with it's thumb and first finger. It simulated natural selection, because traits that didn't allow the individual to collect more food died out.

The pincher phenotype was the best at picking up food. It was able to collect the most food with each grab, and was able to store it somewhere the quickest. The stumpy phenotype was unable to collect food well, and took a long time to store it. The knuckler phenotype was in the middle, not as slow as stumpy but not as fast as pincher.

We asked the question, "Do populations evolve?" We determined that the population did evolve. Evolution is defined as the change of allele frequency over time. The alleles we measured are the allele for how the individual can collect food. All alleles started off at about the same amount, but after one "year," the "a" allele frequency decreased dramatically, because all the stumpy phenotypes died. The allele frequency went from 48% A allele and 52% a allele to 31% A allele and 69% A allele. This was a change in allele frequency, so the population evolved. The allele frequency continued to change, so the population continued to evolve.

Allele Frequency Over 7 Years

In this lab, like in nature, some things were random, while others were not. The placement of food was random, sometimes spread evenly, sometimes in piles, and once all in the same spot. This made the survival random and linked to whether you were close to the food. Another random aspect was offspring. The alleles selected from offspring were a 50-50 chance. At the same time, offspring weren't random. You could choose your mate and possibly guarantee a certain phenotype, which increased the frequency of that allele.

The results of this lab would have been very different if the food was a different size. Making the food smaller would have made it a lot harder for the already struggling stumpy phenotype, and would have helped both knuckler and pincher phenotypes. Making the food larger would have helped the stumpy and pincher phenotypes, but would have immensely harmed the knuckler phenotype, causing a disruptive selection pattern.

If there was no incomplete dominance, meaning the knuckler phenotype wouldn't exist, then there would eventually be no more stumpy phenotype, and that means no more A allele. After one year, there was no more stumpy phenotype, and if there was no incomplete dominance, then any individual with the A allele would be a stumpy, and then die.

Natural selection lets the best phenotypes survive, and makes them more common, which changes the allele frequency. Because the allele frequency is what determines if a species evolves, that means natural selection causes evolution.

There were many different strategies to increase survival and reproduction. One was to go where there was the least competition, so no one would steal food. Another was to have easy storage for food, like the hood of a hoodie sweater. Another strategy was cheating and not using the phenotype they had. Because everyone had access to at least one of these strategies, it meant that whoever had an advantage no one else had would survive, and the pinchers had that advantage. In nature, the species with the best phenotype will win, but the strategies don't get passed down unless they are genetic. This means that if someone is very aggressive in food collection, their offspring might not be.

In evolution, populations evolve, not individuals, because individuals can't change their genotype. Natural selection acts on the phenotype of an individual, deciding whether it will survive or not. This is because the phenotype is the physical thing that helps or harms the organism, not the genotype.