midterm 2

Question 1

a population has been isolated from another due to a highway, they are now re-connected with a bridge, how will this effect Fst ?

Answer 1

Fst value will decrease

more mixing = Fst = 0
— (lots of gene flow)

fixed populations (all same) = Fst = 1
— no gene flow

Question 2

Ka/Ks OR dN/dS &laquo_space;1 (or 0)

Answer 2

strong purifying selection

Ka«Ks

Question 3

Ka/Ks OR dN/dS &raquo_space; 1

Answer 3

positive selection

Ka»Ks

Question 4

Ka/Ks OR dN/dS is approx 1

Answer 4

evolving close to neutrally

Ka = Ks

Question 5

difficulties of biological species concept

Answer 5

— Many populations are allopatric
— The concept does not apply to clonal organisms
— Testing reproductive isolation in the lab is not always feasible
— The concept cannot be applied to extinct species

Question 6

Michael Desai’s lab with yeast

Answer 6

— Deleterious mutations became fixed in the asexual lines because of linkage disequilibrium with beneficial mutations.
— Deleterious mutations did not get fixed in the sexual line because recombination removed linkage with beneficial mutations.
— More nonsynonymous mutations became fixed than synonymous ones because nonsynonymous mutations are more likely to affect fitness

Question 7

linkage disequilibrium

Answer 7

non-random association of alleles at different loci

• human Y chromosomes have higher linkage disequilibrium than human X chromosomes

when beneficial mutation sweeping thru population — higher levels of linkage disequilibrium (more linked) and decreased variation

Question 8

do sexual or asexual lineages have higher extinction rates ?

Answer 8

asexual

Question 9

bateman’s principle

Answer 9

with repeated matings, male fitness often increases more than female fitness

males often have greater variance in reproductive success than females (greater opportunity for sexual selection)

ex// elephant seal females all produced successful offspring where some males didnt have any