Question

You are a chicken farmer in Hyattsville, MD and you have lots of chickens. Some lay brown eggs and some lay white eggs. By doing some quick counts over the past few weeks you see that your chickens lay about 80% white eggs and 20% brown eggs. A flash flood strikes your farm the next week. You save two of your 6 coops, the rest of the chickens are washed away. You move your remaining lucky chickens to higher ground, re-building the farm. Six months later, you re-do your egg count to find that your chickens are laying 60% brown eggs and 40% white eggs. What might be influencing this population? Why?

Answer 1

The proportion of Brown:White eggs shifts from 4:1 before the flash floods to 3:2 after the flash foods. This is likely because of Genetic Drift. Since 4 out of 6 coops washed away during the flash floods, the chickens must have a higher frequency of the allele causing the eggs to be white after the flash floods as compared to before.

This would cause the frequency of the alleles in the population to shift, affecting egg phenotype.