Lab 1: Evolution -- Dawn of the Planet of the Pintos, by Team 🔥🔥
Team Members: Horea Oprean and Jonathan Hong


Hypothesis: Genetic Drift will be modeled through 10 generations of random selection of 4 bean types, representing allele frequency.


Null Hypothesis: That the bean population will be in Hardy-Weinberg equilibrium, and the bean frequencies will be in the same proportion over the 10 generations.


Figure 1. Chart of population of four bean types over the 10 generations represented in the experiment.

Type of Bean	Observed (O)	Expected (E)	(O-E)²/E
White	0	11	11.0
Black	1	11	9.09
Pinto	49	15	77.07
Round	0	13	13.0

Table 1. Observed, expected, and chi-squared data of beans selected randomly to demonstrate natural selection.

Analysis: Our bean data differed significantly from the prediction of the null hypothesis, giving us a chi-squared value of 110.16, which yielded a p-value of less than 0.0001¹ with 3 degrees of freedom. This is extremely statistically significant and suggests that the bean population was not in Hardy-Weinberg Equilibrium.


Conclusion: Our chi-squared value of 110.16 was sufficient enough to reject the null hypothesis due to the critical value for 3 degrees of freedom being 7.82, but our data did not support our hypothesis. We believe that the dominance of the pinto bean (the largest bean) in the later generations and extinction of the white and round beans (the smallest beans) was due to the size of the bean affecting the "randomness" of the beans being selected -- the larger the bean, the more likely it was to the towards the top of the cup from which the beans were drawn, and the easier it was to grab the bean. This suggests a correlation between the size of the bean and its fitness in the environment, and that our experiment did not model genetic drift so much as it modeled natural selection. We believe that a new experiment done with a random bean selection method that did not take differences in bean morphology into account would better model genetic drift.

¹According to the calculator at http://www.graphpad.com/quickcalcs/pvalue1.cfm