Hunger Games Lab

1. In this lab, we simulated real-life natural selection patterns through an experiment involving picking up food (corks) in various ways based on three different phenotypes: stumpies (AA), knucklers (Aa), and pinchers (aa).

   

   Lab overview and procedure

2. Knucklers and pinchers were the best at catching food, as knuckles or fingers were better for picking up food, and thus survived the most. The small a allele increasing significantly in frequency supported this, going from 50% of the gene pool to 0.74% of the gene pool in round 5.
3. In our experiment, our population evolved, as the allele frequencies shifted significantly due to differences in individual phenotypes.  The frequencies of the large A and small a alleles went from 0.5 and 0.5 to 0.38 and 0.62 over the course of the experiment. In addition, at the end of the experiment, there were 14 knucklers, 6 pinchers, and 1 stumpy from the 10-10-10 makeup of the beginning; all of the data points to a gradual shift in the gene pool of the population. 



Graph of allele frequency over time in experiment

4. Much of the changes in this experiment were due to non-random factors (e.g. natural selection). However, random events also impacted the experiment; genetic drift caused by changes in the food dispersion, as well as cheating to survive both affected the data. When the food was gathered in piles near some individuals, they were able to collect more food and thus survive and reproduce better. Additionally, some individuals resorted to cheating (i.e. grabbing technique) when selective pressures were high, and thus had an advantage unrelated to their traits.
5. In nature, when resources and conditions change, individuals and populations are affected: adaptations come into effect, and some individuals die out as a result of being unfit for the new conditions. For example, if an invasive species were to be introduced into the area, it might kill off or compete with the population, thus causing fewer individuals to survive. Similarly, the results of the lab may have been different if some key factors were changed. If the food was larger, the stumpies may have fared better, with an easier time picking up the food. On the other hand, if the food was smaller, it might benefit the pinchers, as they have an advantage picking up smaller food over the other phenotypes.
6. If there were not incomplete dominance, then there would be many more stumpies (making up 75% of the potential genotypes from a double heterozygous cross), as they are a result of the dominant big A allele. Conversely, without the knuckler phenotype, the pinchers would quickly outcompete the stumpies and dominate the population.
7. In this lab, we saw how natural selection is a major driving force of evolution, as it changes populations to make traits beneficial for survival more common over generations. Our beneficial allele was the small a allele, as pinchers and knucklers were better at surviving, so over time that allele became increasingly prevalent. Therefore, there were more pinchers and knucklers at the end.
8. Individuals adopted new techniques during the experiment. When selective pressures were high, they often cheated with a grabbing technique to increase their chances of survival. This likely led to there being more individuals with inferior phenotypes (i.e. more stumpies survived). Thus, it would have also increased the frequency of large A alleles. In nature, adaptations over time would play a similar role, beneficial mutations leading some to survive while others died off. An example would be the peppered moth: the black phenotype let the moth better camouflage from predators during the Industrial Revolution, and thus individuals with that phenotype had an advantage.
9. Natural selection acts on populations over many generations, and occurs due to beneficial traits of individuals. This can be seen in this lab: the beneficial traits that pinchers and knucklers had to pick up food caused their genes to be passed on more often (survived more often), and thus the population's gene pool was affected.