Evolution Lab 1: The Effects of Gene Drift in Isolated Populations Represented with Beans a.k.a. The Fast and The Furious: Gene Drift.

Team Name: TANG

Members: Nitesh Chetry, Greyson Hamilton, Azar Minhas, Taylor Poffenroth

Hypothesis: Bean size affects the frequency of types of beans found in a generation because they will have certain traits making it easier or harder for them to be picked out of a sample cup.

Null Hypothesis: Bean size does not affect the frequency of beans found in a generation.

Prediction: Larger sized beans will have greater frequency because they are easier to be picked from the cup. Smaller sized beans will have lower frequency because they are harder to pick out from the cup. As the beans are doubled and repicked between generations, the larger beans will increase in frequency, and the smaller beans will decrease in frequency.

Graphs:

Figure 1: The number of beans represents the allele frequency through generations in this simulation of natural selection. The number of beans (allele frequency) is the dependant variable in this experiment residing on the y-axis and the generations through which the beans survived through is the independent variable on the x-axis. All beans curve toward zero except the speckled variety. By the 5th generation only 1 circular bean, 2 white beans, and 5 black beans remained, while in that same generation 42 speckled beans remained. In the first generation the Beans were in numbers of  8, 18, 15, and 9 all in order with respect to their listing on the graph above. By the 8th generation only speckled beans were left in the test group, thereby becoming the dominant and only remaining allele in the simulated test group.

Figure 2: This graph depicts a simulation of genetic drift done with beans used to represent allele frequency over time in a simulated population. On this graph the independent variable (x axis) is the generations and number of beans is the dependent variable (y axis).  Through the generations we can see that Speckled though it only started with 7 rose to become the dominate allele in this simulation. While speckled became the dominate bean/allele other beans started to slowly decrease at first then finally after the 8th generation become extinct. This left just the speckled bean to completely dominate the simulation.

Analysis & Conclusion:

Our hypothesis,“the size of a bean would affect how often a bean was picked,” was  supported by our experimental results. For population A, in generation 1, all the beans were present in varying amounts, speckled at 18, black at 15, white at 9, and circular at 8.  By the end of the experiment only the speckled beans remained at a number of 50, making up the entire population.  This result was most likely caused by natural selection, as the speckled bean was much larger, and thus, easier to grab out of the container in which the test pools were held.  This natural propensity to be picked up was a competitive advantage in this type of experiment, and allowed for the speckled bean to be continuously chosen over its counterparts.  Another testament to this interpretation would be the Chi-squared values found between the first and last generations.  Population A, with a Chi-squared value of 88.89, and population B, with a Chi-squared value of 307.14, were both vastly greater than the critical value of 7.82.  This massive difference in both population’s values lends us to reject the null hypothesis, that size does not matter, and further supports our initial hypothesis.