HWE: Genetic Drift - 10

Question 1

Define genetic drift

Answer 1

a random element in evolution
allele frequencies in populations change from generation to generation due to chance

Question 2

Drift can act on _____ or ____

Answer 2

gametes or individuals

Question 3

Drift does not result in _____ but can lead to ____

Answer 3

adaptation
loss or fixation of alleles

Question 4

What is the relationship between sample size and sampling error

Answer 4

as sample size increases, sampling error decreases
because getting a better representation of the population

Question 5

Genetic drift is most important in ____ populations because

Answer 5

small
because they have an increases sampling error and are more susceptible to extinction and the effects of genetic drift

Question 6

Define population bottlenecks

Answer 6

events that randomly remove most members of a population
ex. flood, volcanic eruption

Question 7

Define founder effect

Answer 7

processes that randomly disperse a small number of individuals to a new location and these individuals form a new population. Chances are there won’ t be an equal representation moving to the new location

Question 8

Describe the different effects of migration vs. genetic drift

Answer 8

migration = increases genetic variation and decreases differences among population
genetic drift = decreases genetic variation, increases differences among populations

Question 9

Do you see stronger effects of genetic drift in older populations or younger populations

Answer 9

older because they have lived through and be affected by more random changes than younger populations
means older populations have the lowest level of genetic variation because subject to drift longer

Question 10

What can counteract the effects of bottleneck and genetic drift to increase genetic variation

Answer 10

introduce gene flow (unrelated individuals from other populations to the population that is suffering from genetic drift effects)

Question 11

In Illinois prairie chicken example, what are the 2 reasons that could cause hatchability to decrease

Answer 11

1. migration is decreased due to habitat fragmentation
2. mutational meltdown

Question 12

describe the extinction vortex

Answer 12

genetic drift effects occur which decrease population size which increase rate of drift which increase rate of fixation of deleterious alleles and decrease fitness which continues to lead to decrease in population size

Question 13

What 3 concepts result from genetic drift causing fluctuations to be random

Answer 13

1. each population has unique trajectory
2. fixation or loss of some alleles
3. frequency of heterozygotes decreases

Question 14

The probability that an allele will become fixed is equal to its…

Answer 14

initial allele frequency

Question 15

What is the equation to calculate probability of an allele becoming fixed

Answer 15

X/2N
x = number of copies of the specific allele
N = number of individuals

Question 16

Why does heterozygosity decrease with genetic drift

Answer 16

because genetic drift leads to fixation of one allele in a population and therefore removal of others