Population Genetics

Question 1

gene frequency

Answer 1

allele frequency

Question 2

gametic array

Answer 2

frequency of each type of allele in the population

Question 3

genotypic array

Answer 3

frequency of each genotype in the population

Question 4

Hardy-Weinberg Law

Answer 4

allele and genotypic frequency will arrive at and remain at equilibrium frequencies after one generation of random mating if all assumptions are met

Question 5

What are the assumptions of Hardy-Weinberg

Answer 5

• infinitely large population - random mating - no selection - all are equally fit - no migration - no mutation

Question 6

panmictic

Answer 6

random mating

Question 7

Equilibirum equation for Hardy- Weinberg

Answer 7

p^2AA + 2 pqAa + q^2aa

Question 8

degrees of freedom for Hardy-Weinberg chi2

Answer 8

genotypes - # of alleles

Question 9

What factors increase genetic variation within populations

Answer 9

mutation migration some types of natural selection

Question 10

What factors increase genetic variation between populations?

Answer 10

mutation genetic drift some types of natural selection

Question 11

What factor decrease genetic variation within populations?

Answer 11

genetic drift some types of natural selection

Question 12

What factors decrease genetic variation between populations?

Answer 12

migration some types of natural selection

Question 13

mutation

Answer 13

• source of genetic variation - origin of new alleles

Question 14

p_t = 1 - p0*µ = (1-µ)p_t-1

Answer 14

Frequency of A in subsequent generations when mutations shift from A to a

Question 15

q₁ = p₀µ

Answer 15

frequency of a in subsequent generations when mutations shift from A to a

Question 16

p₁ = (1-µ)pt₀ + vq₀

Answer 16

frequency of A in subsequent generations when reverse mutation is also occuring with shift form A to a

Question 17

gametic array in generation 1 when reverse mutation is occurring

Answer 17

[(1-µ)p₀ + vq₀]A + [(1-v)q₀ + µp₀]a

Question 18

migration

Answer 18

change in gene frequency depends on…

• migration rate
• gene frequency of the immigrants

Question 19

frequency of A allele after migration

Answer 19

p’ = (1-m)p + mP

where…

P = frequency of A on donor population

p = frequency of A on island population

m = proportion of migrants after immigration = immigrants/total now on island

Question 20

fitness

Answer 20

the ability to survive and reproduce

Question 21

If no selection, the fitness values…

Answer 21

are 1 for all genotypes

Question 22

If the a is recessive lethal, aa has a fitness value of…

Answer 22

0

Question 23

If the heterozygote is the most fit…

Answer 23

it is overdominance

Question 24

If the heterozygote is least fit…

Answer 24

if is underdominance

Question 25

directional selection

Answer 25

• favors one extreme
• population mean increases or decreases depending on which extremem is favored

Question 26

disruptive selection

Answer 26

• advantage for both extremes
• leads toward bimodal population
• underdominance

Question 27

stabilizing selection

Answer 27

• heterozygotes favored
• decreases variance
• leads to polymorphisms
• overdominance

Question 28

viability selection

Answer 28

some individuals are more likely to survive to reproduction than others

Question 29

assortative mating

Answer 29

mate based on phenotype

can be positive or negative

Question 30

positive assortative mating

Answer 30

mating like individuals together results in simular situations as inbreeding (increased homozygotes but only for loci in mate selection

Question 31

negative assortative mating

Answer 31

“opposites attract”

keeps diversity in the population

tends to increase the frequency of heterozygous individuals for the loci in mate selection

Question 32

inbreeding

Answer 32

mating of related individuals

changes frequency of genotypes but not alleles

lead to more homozygous individuals in population over time

affects all loci in the organism

Question 33

non-random mating changes…

Answer 33

frequency of genotypes but not alleles

Question 34

equation to account for inbreeding

Answer 34

(p² + Fpq)AA + 2(1-F)paAa + (q² + Fpq)aa

Question 35

How to calculation F

Answer 35

this is the inbreeding coefficient

• calculate the frequency of the alleles
• solve for F based on the modification of the genotypic array due to inbreeding

p² + Fpq = known frequency

Question 36

describe the impact of inbreeding

Answer 36

• does not alter allele frequency
• alters genotypic frequencies
  
  • increases both homozygotes
  • decreases heterozygote
  • eventually everyone will be homozygous and the genotypic array will be pAA + qaa

Question 37

What are examples of effects of small population size?

Answer 37

random drift/genetic drift

founder effect

inbreeding

Question 38

What are examples of nonrandom mating

Answer 38

positive assortative mating

negative assortative mating

inbreeding

Question 39

random drift/genetic drift

Answer 39

random loss and fixation of alleles

sampling error - due to small sampling of alleles in the next generation, only gametes of one type make it into the progeny

Question 40

founder effect

Answer 40

• small population colonizes new area
• small size makes it likely to undergo genetic drift
• allele frequency in founder may differ from the original population
• they will undergo different, often harsher, selection pressure allowing more rapid change

Question 41

Bottle neck

Answer 41

a disaster wipes out a large portion of the population

the surviors rebuild but with different allele frequencie