Question

For questions 3.1 - 3.3, select the option that will result in a SMALLER amount of linkage disequilibrium 5 generations after a selective sweep.

3.1 Consider a gene under selection. Which option will result in a SMALLER amount of linkage disequilibrium?

a. The selected gene was in a region with a low recombination rate.

b. The selected gene was in a region with a high recombination rate.

c. The selected gene was in a region with a recombination rate equal to the rest of the genome.

3.2 Consider an allele under selection. Which option will result in a SMALLER amount of linkage disequilibrium?

a. The selected allele was a new allele/mutation that was beneficial.

b. The selected allele was an old allele that suddenly became favorable.

3.3 Consider a selective sweep in a population. Which option will result in a SMALLER amount of linkage disequilibrium?

a. The selective sweep occurs in a population with an effective size of 1000.

b. The selective sweep occurs in a population with an effective size of 100.

Answer 1

Linkage Disequilibrium is the measure of non-random association with in alleles positioned at different loci.

3.1 It has been found that recombination rates are significantly co related with the Linkage Disequilibrium which would help in explaining even a small fraction of additional variance. Recombination breaks down the linkage disequilibrium generated between genes

Thus, if recombination rate is high, there will be smaller LD. Option B

3.2 Genes that have the ability to modify recombination rates would reduce recombination after evolving, thus when a beneficial alleles rise from low to high frequency it reduces LD. Option B

3.3 The smaller is the population size; the smaller is the chance of random mating. Hence option B would lead to smaller LD