Genetic Drift (W3-L1)

Question 1

Genetic Drift

Answer 1

change in allele frequencies due to chance events or sampling process

No direction

Infinitely large populations have no genetic drift

Question 2

Founder event

Answer 2

establishment of a new population by a small number of individuals

Question 3

Found effect

Answer 3

a change in allele frequencies that occurs after a founder event due to genetic drift

ex. deaf population on Martha’s vineyard

Question 4

What represents probability of eventual allele fixation?

Answer 4

P

represents frequencies in the population at that momment

Question 5

How does genetic drift affect large vs small populations?

Answer 5

Small populations: -greater impact, reaches fixation at a faster rate, heterozygotes diminish faster

Large populations: reaches fixation at a slower rate, more gradual effect, heterozygotes remain in population for a longer time

Question 6

Effective population size

Answer 6

number of individuals on average who contribute to the genepool

always smaller than census

does not take into account disease, pop fluctuation, small breeding groups, sex ratio, etc.

Question 7

Mean allele frequencies in respect to genetic drift

Answer 7

similar in small and large populations

Question 8

Variance in frequencies with respect to genetic drift

Answer 8

greater frequencies in small populations

Question 9

What are the effects of Inbreeding?

Answer 9

in small populations:

• drift reduces heterzygocity
• individuals becomes genetically more similar
• inbreeding increases (even if mating is random)