(06) Population Genetics

Question 1

(Hardy-Weinberg Equilibrium)

1. This theory is useful in understanding what happens to what in real populations?
2. If frequency of allele A = p, and frequency of allele a = q, then p + q = ?
3. At Hardy-Weinberg equilibrium, genotype frequencies will be: (give the equation)
4. Does the equation apply to more than two alleles?

Answer 1

1. what happens to allele and genotype frequencies
2. 1
3. p^2 + 2pq + q^2 = 1
4. Yes - the equation just gets longer

Question 2

What 6 conditions are necessary for H-W equilibium?

Answer 2

1. random mating
2. large population
3. no migration
4. no selection
5. negligible mutation rate
6. non-overlapping generations

Question 3

(Factors that modify Hardy-Weinberg Equilibrium)

1. What is non-random mating?
2. What is positive assortative mating? Common in natural habitats? Does it affect allele frequencies? genotype frequencies? Results in the increased frequency of what type of genotype?
3. What is Negative assortative mating? What type of preference? Results in increase of what type of genotypes?
4. Does assortative mating affect anything beyong the loci involved in the expression of the phenotypic trait and the loci that are linked to them?

Answer 3

1. when mates are chosen on the basis of phenotypic characteristics
2. like with like (inbreeding); yes; no; yes; homozygous genotypes
3. “opposites attract”; exotic preference; heterozygous genotypes
4. no

Question 4

(Factors that modify Hardy-Weiberg Equilibrium)

(Inbreeding)

1. Mates are chosen based on what?
2. Mates are more closely related than would be predicted by chance
3. In what two ways does this occur
4. How are effects of inbreeding similar to assortative mating? how are they different?

Answer 4

1. degree of relatedness
2. -
3. 1) systematic choice of relatives as mates 2) subdivision of population so individuals have narrower choice of mates
4. both increase homozygosity; inbreeding affects all loci across whole genome

Question 5

1. What four things does inbreeding lead to?
2. How many lethal recessive equivalents does the average human carry?

Answer 5

1. 1) loss of genetic variation

2) increased expression of hidden recessive alleles
3) increased frequency of lethal mutations in small gene pools
4) reduced “fitness” (inbreeding depression)
2. 4

Question 6

Effects of inbreeding (look at this a little)

Question 7

(Factors that modify HW Equilibrium)

Population Size

1. What is the random fluctuation in allele frequencies due to “sampling error” in small populations?
2. Fixation of allels (everyone has the same allele) is common in populations of less than what?

Answer 7

1. genetic drift
2. 1000

Question 8

What does this graph show?

Answer 8

• that for example - if an allele’s frequency is .5 - you would have to select 6 individuals from that population to assure that there would be a 95% of one of them having that allel

Question 9

(F that MOD HW EQ)

(Population size)

1. What is the effective population size?

Answer 9

1. the number of adults contributing to the next generation

Question 10

(Factors that Affect HW EQ)

(Population Size)

What is it called when a new population is started from a small number of founders?

How will the new population differ from the original population?

Answer 10

• Founder Effect
• new population will have different allele frequencies (sampling effect)

Question 11

(Factors that Mod HW EQ)

1. What is the movement of alleles between populations” (or when individuals from populations with different allele frequencies disperse and mix)
2. What is the effect of migration on the allele frequencies?
3. After one generation of random mating the combined population will be in what?
4. The combined pop will be out of HW equilibrium to the extent that what is what?

Answer 11

1. migration
2. works to equalize allele frequencies among populations
3. HW equilibrium
4. mating is non-random

Question 12

look at this

1. How many individuals per generation need to migrate to keep allelic variation (in certain sized populations)

Answer 12

then this

1. just one

Question 13

(Factors that Modify HW EQ)

1. What is the fact that not all individuals are equal in survival or reproduction called?
2. What does selection act against?

Answer 13

1. selection
2. Acts against a phenotype(s) to alter the frequency of alleles in subsequent generations

Question 14

(Domestic Animal Breeding Programs)

What are the two main things it does? (Don’t worry about learning the subpoints - just read them)

Answer 14

1. Enchance genetic progress (selection within lines, combining favorable genes between lines, uniform product)
2. Management applications (control inbreeding, control heterosis (hybrid vigor), parentage testing, individual/line identification (genetic barcode))

Question 15

(Zoo Populations)

1. Populations are limited in size
2. In many cases animals were collected from the wild decades ago and there is little to no info on animal origin
3. In many cases it is no longer possible or responsible to collect more from the wild
4. vast majority of animals are captive born

Question 16

(Captive Animal Breeding Programs)

1. Cooperative program of planned breeding among zoos usually coordinated by a regional zoo association
2. Reason for cooperative program is conservation related ad/or inteded to create a long-term, viable captive population

Question 17

(Goal of Genetic Management)

1. Maintain in captivity populatinons as genetically similar to the wild-caught animals as possible
2. Is goal to avoid all inbreeding?
3. Is goal to select for captivity (domestication)?
4. Is goal to select for or against traits?

Answer 17

1. -
2. not necesarilly
3. no
4. no