Lab1-Evolution-AB: The Era of Pinto Beans over the Others by Supporting of Natural Selection by Amelia, Evan, Octavia and Tu

Hypothesis and Prediction:

In this lab section, we tested the effect of natural selection on the frequencies of alleles in two distinguished populations originated from the same population. There were four different types of beans used to represent for four alleles of a trait in the genotype: round, pinto, black, and white beans. The allele frequency of the populations of beans will change by the 10th generation due to natural selection because the pinto beans are larger and will, therefore, be picked more than the other beans. Our prediction was that there were changes in the frequencies of alleles in the 10th generation that were different from the beginning of each population. Particularly, the number of pinto beans would increase from generation to generation and the other beans or “alleles” would eventually die off. Our null hypothesis was there was no change in the allele frequencies between the beginning generation and the last generation. Based on this hypothesis, there would be no impact of neither natural selection or genetic drift on the allele frequencies.

Graphs:

Figure 1.  The number of beans (including round, pinto, black, and white) picked randomly in 10 generations in population A (performed by Octavia and Evan). The total number of beans picked in each generation was 50. The two populations (A and B) originated from a common population (shared ancestor) and were divided by “natural barrier”. Each type of bean was represented for an allele in the population. Data was collected in Lab 1, Jan 03 2017 by Octavia and Evan.

Figure 2.  The number of beans (including round, pinto, black, and white) picked randomly in 10 generations in population B (performed by Amelia and Tu). The total number of beans picked in each generation was 50. The two populations (A and B) originated from a common population (shared ancestor) and were divided by “natural barrier”. Each type of bean was represented for an allele in the population. Data was collected in Lab 1, Jan 03 2017 by Amelia and Tu.

Analysis:

After analyzing our data and observing the numbers of pinto beans in generation 10 of other groups, we can say that the reason for the largest number of pinto beans over the others in generation 10 (as shown in Figure 1 and 2) is due to natural selection. The calculated chi-square numbers are 187.7 and 119.9 respectively for population A and B. Through these numbers, we can reject our null hypothesis of that there would be no significant change in the allele frequencies, which were represented as the number of four types of bean (pinto, round, black, and white).

The number of pinto beans selected had changed the allele frequencies because they were getting larger and picked more often due to the larger size and advantage over the other beans. For our lab group, we picked the beans as randomly as we could by using our red cup and selected beans from it. Once our cups had more than half of pinto beans there was little probability of selecting any other kinds besides the pinto beans. That  resulted in the last generation of both populations were mostly pinto beans, where in population A it had killed off the round beans, and in population B it had killed off the round and the white beans. For this to be a result of natural selection, we would first need to have variation present in the starting population. We would also need differential reproduction and heredity. For this lab, we did start with a variation of the “alleles” by determining each bean type as a different allele in the population. We also had differential reproduction because as a result, the pinto beans were able to pass on the offspring more than the other beans due to the size advantage. Lastly, the beans that were selected, but most of them were pinto beans, were considered the next generation and heredity are shown through the pinto beans remaining the larger beans. This leads to the conclusion of natural selection which caused the variation of our population to diminish leaving little to no other beans in both populations and if continued it likely would have lead to all of our populations to be pinto beans.

Conclusion:

The chi-square values we had for Population A was approximately 187.7, and for Population B was 119.9. Both of them were greater than the probability value, which means according to Chi-Square statistics, we then rejected our null hypothesis. In both populations, there were only few pinto beans that were chosen in our first generations. However, from that point on the pinto beans had gradually increased in numbers over generations due to the fact that they were larger and therefore easier to grab from the cups. The pinto allele quickly became the dominant allele, due to our data gathered from the simulation. As a result, the pinto bean or “allele” gradually increased from the initial numbers in generation 1 to the final much larger numbers found in generation 10.