Lecture 19

Question 1

F

Answer 1

• Inbreeding co-efficient

Question 2

H

Answer 2

• Heterozygosity

Question 3

N

Answer 3

• Population size, the number of breeding intividuals

Question 4

t

Answer 4

• Generation time

Question 5

Autozygous (F):

Answer 5

• The probability of that any two randomly chosen alleles in a population are identical by descent
• A1A1 or A2A2 from the same A1 or A2

Question 6

Allozygous (1 - F):

Answer 6

• The probability of that any two randomly chosen aleles in a population are NOT identical by descent
• A1A1 or A2A2 from different A1 or A2

Question 7

Generational increase in frequency of homozygotes in a selfing population:

Answer 7

• G0 AA 0, Aa 1, aa 0
• G1 AA 1/4, Aa 1/2, aa 1/4
• G2 AA3/8, Aa1/4, aa 2/8
• G AA 1/2, AA 0, aa 0

Question 8

Effects of inbreeding:

Answer 8

• Decrease in heterozygosity
• Increase in homozygosity
• Allele frequencies do not change

Question 9

Hardy Weinburg Equilibrium:

Answer 9

• A1A1 = 2pq -2pqF

- p + q = 1

Question 10

Homozygous:

Answer 10

A1A1 = p squared (1 - F) + pF

Question 11

Heterozygous:

Answer 11

A1A2 = 2pq (1-F)

Question 12

Calculating F from observed genotype frequencies:

Answer 12

A1A2 = 2pq (1-F)

• Allele frequency of A1
• Allele frequency of A2
• Observed heterozygosity
• F =

Question 13

Reduction in heterozygosity is a convenient measure of the effect of inbreeding in a population:

Answer 13

• F = (Hexp - Hobs) / Hexp

Question 14

Can we predict how fast F increase and H decrease over time in a finite population?

Answer 14

• Yes

-

Question 15

Ft = 1 - [1-1/2N] t the power t (1-Fo)

Answer 15

F = Level of inbreeding in generation t
N = Population size
t = Generation
o = Level of inbreeding in the base population

Question 16

Ht = Ho [1-1/2N] to the power t

Answer 16

Ht = heterozygosity in generation t
Ho = Heterozygosity in the base population
t = generation
N = population size

Question 17

From generation t to t+1, there are 2 ways to get alleles IBD

Answer 17

• 1/2N
• Probability of an individual receiving two copies of the same allele (new inbreeding)
  OR
• [1-1/2N] Ft
• Probability of an individual receiving copies of two different alleles from generation t, but those alleles are identical by descent from generation t-1 (previous inbreeding)

Question 18

Increase in inbreeding (F) over time in finite populations:

Answer 18

Ft = 1 [1 - 1/2N]to the power t

• F will increase over time as a function of population size (N)
• When N is large, F increases slowly over time
• When N is small, F increases rapidly over time

Question 19

Decrease in heterozygosity over time in finite populations:

Answer 19

Ht = Ho [1-1/2N] to the power t

• H will decrease over time as a function of population size (N)
• When N is large, H decrease slowly over time
• When N is small, H decreased rapidly over time