Population Genetics

Question 1

What do haploid gametes show allele frequency or genotype frequency?

Answer 1

Allele frequency

Question 2

What do diploid gametes show allele frequency or genotype frequency?

Answer 2

Genotypic frequency

Question 3

What is population genetics theory?

Answer 3

The frequencies of alleles and genotypes in a population will remain constant unless acted upon by non-mendelian processes
(equilibrium = no evolution)

Question 4

How did Theodosius Dobzhansky define evolution?

Answer 4

“a change in the frequency of an allele within a gene pool”

Question 5

What does a mendelian inheritance patterns allow us to predict?

Answer 5

Expected frequencies of alleles

Question 6

When do frequencies of alleles remain constant?

Answer 6

in offsprings

Question 7

What does p stand for in the hardy-weinberg equilibrium?

Answer 7

the frequency of one allele in the

population (usually the dominant allele)

Question 8

What does q stand for in the hardy-weinberg equilibrium?

Answer 8

the frequency of one allele in the

population (usually the recessive allele)

Question 9

What is hardy-weinberg equilibrium equation?

Answer 9

p^2 + 2pq + q^2 = 1

p + q = 1

Question 10

What does p^2 stand for in the hardy-weinberg equilibrium?

Answer 10

Proportion of population that is homozygous for the first allele

Question 11

What does 2pq stand for in the hardy-weinberg equilibrium?

Answer 11

Proportion of population that is heterozygous

Question 12

What does q^2 stand for in the hardy-weinberg equilibrium?

Answer 12

Proportion of population that is homozygous for the second allele

Question 13

When does the hardy-weinberg equilibrium apply?

Answer 13

• Organisms are diploid, sexual and have discrete generations
• Allele frequencies are the same in each sex
• Mendelian segregation occurs
• Mating occurs at random
• Population size is large so no genetic drift
• No gene flow (immigration/ emigration)
• No mutation
• No selection

Question 14

Why must mating occur at random when using the HWE?

Answer 14

Non-random mating does not change allele frequencies, but rather changes how the alleles are distributed into diploid genotypes

Question 15

What is assortative mating?

Answer 15

• Race and geographical proximity

- Mating is generally random with respect to genotypes

Question 16

What is positive assortative mating?

Answer 16

People that looks the same

Question 17

What is negative assortative mating?

Answer 17

People that looks the different

Question 18

Why must the population be large so no genetic drift when using the HWE?

Answer 18

• Because genetic drift affects smaller populations more than larger populations.
• Genetic drift reduces genetic variation.

Question 19

What is genetic drift?

Answer 19

Allele frequency change due to chance as a result of sampling error.

Question 20

Why must there be no migration or gene flow when using the HWE?

Answer 20

• Migration transfers individuals amongst populations.
• Gene flow transfers alleles amongst populations.
• Can either ↑ or ↓ genetic variation.

Question 21

Why must there be no mutations when using the HWE?

Answer 21

• Mutations increase genetic variation.
• Some mutations create dominant alleles, some create recessive or co-dominant alleles.
• Mutations may be harmful, neutral, or favourable.
• Effect depends on the environment

Question 22

Why must there be no selection when using the HWE?

Answer 22

• biases which genotypes are transmitted to the next generation.
• can either ↑ or ↓ genetic variation depending on the type of selection.
• can operate in many different ways.

Question 23

What is linkage disequilibrium?

Answer 23

Deviations from the expectations of independent segregation and Hardy-Weinberg equilibrium caused either by physical linkage or population demography

Question 24

How do you workout the HWE and linkage probability?

Answer 24

D = pAB x pab - pAb x pAB