Week 21

Question 1

Define genetic drift and gene flow

Answer 1

Genetic drift is the changes in allele frequency in a population due to random variation in death and reproduction.

Gene flow is the process of alleles moving from one population to another

Question 2

How can genetic drift and gene flow cause allele frequencies in a population to change overtime

Answer 2

Genetic drift: Allele frequencies change due to random chance, like mortality or reproduction, which has a larger effect in small populations​
.
Gene flow: Allele frequencies change when individuals from one population introduce new alleles into another population​
.
Contrast: Genetic drift is random and significant in small populations, whereas gene flow involves direct movement of alleles between populations, often homogenizing genetic variation.

Question 3

What is the effect that genetic drift and gene flow have on average fitness and genetic variation in a population

Answer 3

Genetic drift:
Can reduce genetic variation over time as alleles are lost randomly​
.
Effects on fitness depend on which alleles are lost (neutral vs. beneficial alleles)​
.
Gene flow:
Can increase genetic variation within a population by introducing new alleles​
.
May reduce fitness if maladaptive alleles are introduced

Question 4

Natural selection evolutionnary processes

Answer 4

Allele frequencies in a population change due to
differences in survivorship and/or reproduction due differential success of different traits in a given environment.

Non-Random

Environmental selection and sexual selection

Question 5

Genetic drift

Answer 5

Allele frequencies in a population change/ fluctuate due to chance (random process)
- Random Chance

Question 6

Can random mortality change allele frequencies

Answer 6

yes

Question 7

Why doesn’t genetic drift impact large populations as much as small populations?

Answer 7

Each individual counts more in a small population than in a large population.

Question 8

Founder effect

Answer 8

New population likely to have different allele
frequencies than source population, by chance

Question 9

Genetic Bottleneck

Answer 9

Results when most individuals in a large population die

Question 10

Differentiate between genetic drift in a population vs. a founder effect or bottleneck event.

Answer 10

Genetic drift: Random changes in allele frequencies within any population, often due to random reproduction or mortality
.
Founder effect: Occurs when a small group establishes a new population, and their allele frequencies differ from the original population
.
Bottleneck event: Results from high mortality in a large population, leaving a small group with different allele frequencies

Question 11

Recognize and explain examples of founder effects and bottleneck events.

Answer 11

Founder effect: Example includes the Old Order Amish population with polydactyly.

Bottleneck event: Example includes natural disasters like floods or droughts causing random mortality, leaving a small population.