Exam 3

Question 1

most common measure of divergence

Answer 1

FST

Question 2

When we plot fst s. difference in allele frequency what do we find?

Answer 2

Fst is proportional to the allele frequency difference between two populations

Question 3

Why use Fst and not difference in allele frequency?

Answer 3

•Generalizes to more than two populations

Is the proportion of the total variation that reflects between-population variation

Question 4

What do you notice about the SNPs?

Answer 4

1. Most SNPs exibit some divergence
2. However, for the msot part divergence is smaller than an fst of .5

Question 5

What would cause this processes and why?

Answer 5

1. Genetic drift/not enough time for substantial divergence
2. Genetic drift/counteracted by gene flow
3. Shift in balancing selection equilibrium
4. Divergent selection/counteracted by gene flow

Question 6

Suppose we start with two populations with identical allele frequencies at neutral SNP.

With no migration between populations what will occur?

Answer 6

Genetic drift will occur independently in the two populations and two populaton will diverge

Question 7

Suppose we start with two populations with identical allele frequencies at neutral SNP.

With no migration between populations what will occur if the population remain isolated for a long time?

Answer 7

different alleles can be fixed

Question 8

Why do we see little fixation, and little divergence with Fst > 0.6, in the data?

Answer 8

1. The populations haven’t been separated long enough to allow drift to cause substantial differentiation
2. Gene flow retards or prevents differentiation by drift