Scientists went out and sampled individuals from the populations. Population siz

Question

Scientists went out and sampled individuals from the populations. Population size can be very difficult to estimate, so scientists often assume all populations are approximately the same size (as we are doing here). When they directly sampled one of the populations, they found that there are approximately 30 breeding females and 20 breeding males (males have a higher mortality rate than females) in the populations (remember that we are assuming that all populations exhibit the same patterns). Also the scientists were able to use capture/recapture methods to determine that the proportion of migrants (migration rate: m) in any given population per generation is 0.01. Scientists assume that migration is equal among all the populations (this might be somewhat unrealistic since migration might be more difficult among populations that are separated a longer distance, but for the purposes of this assignment we will assume all migration is equal). When they actively looked at the difference in survival among the different phenotypes they found that survival of the agouti phenotype was approximately 63%. The survival of the black-backed phenotype was approximately 62.8% and survival of the melanistic phenotype was approximately 62.6%.

In order to follow up with the gene flow analysis, you decide to directly measure selection on the fur color by using the survival estimates relating fur coloration. What is selection on the different phenotypes? Given this new information, and using a quantitative explanation, is drift or selection responsible for fixing the allele frequencies? (hint: you will need to use an equation that relates selection and drift, and you will need to do it for ALL 3 alleles) (3 points)

Explanation / Answer

Ans- selection coefficient is = 1-w

So w will be =

For agouti = 63/188.4 = 0.33

For black backed = 62.8/188.4 = 0.33

For melanistic = 62.6/188.4 = 0.33

W is same so selection will also remain same = 1-0.33 = 0.67

The natural selection is same for all the three alleles so this change might be due to genetic drift.

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