Mating Systems

Question 1

list and describe the 2 types of mating systems?

Answer 1

1. random: Hardy-Weinberg, genotypic frequencies dependent upon allelic frequencies
2. non-random: strategic for genetic change

Question 2

what are the 2 types of strategies for genetic change?

Answer 2

selection and mating systems

Question 3

describe selection

Answer 3

deciding which individuals to retain as parents who will contribute to subsequent generation

Question 4

what are the 2 goals of selection?

Answer 4

1. increase frequencies of alleles with desirable effects

2. decrease frequency of alleles with undesirable effects

Question 5

describe mating systems

Answer 5

which males mated to which females

Question 6

what does the application of mating systems lead to?

Answer 6

further changes in allelic frequency beyond those accomplished by selection

Question 7

what do mating systems do to genotypic frequencies?

Answer 7

alters them, changes the proportion of homozygous to heterozygous individuals in offspring generation

Question 8

what are the 2 kinds of mating systems?

Answer 8

random and nonrandom

Question 9

describe random mating systems

Answer 9

Hardy Weinberg, any male can mate with any female, and there is no attempt by a breeder to pair specific mates

Question 10

describe what happens in nonrandom mating systems

Answer 10

the expected proportion of homozygous and heterozygous individuals deviate from HW expectations

Question 11

what two ways is assignment of mates in nonrandom mating systems based on?

Answer 11

1. genetic relationship

2. phenotypic similarity

Question 12

what are the 2 ways of assigning mates based on genetic relationship in nonrandom mating?

Answer 12

1. inbreeding

2. outbreeding

Question 13

what are the two ways of assigning mates based on pehnotypic similarity in nonrandom mating?

Answer 13

1. positive assortative

2. negative assortative/dissasortative

Question 14

what is inbreeding?

Answer 14

attempt to make individuals more homozygous for superior genes of ancestor, mating between members more related than average of population

Question 15

what is the inbreeding coefficient?

Answer 15

the probability that 2 alleles at a locus are identical by descent (IBD), a reflection of the increased proportion of homozygous loci in an individual, quantified by Fx

Question 16

what is outbreeding?

Answer 16

increases heterozygosity, used in commercial meat animal production, mating between individuals less related than average of the population

Question 17

what is the genetic effect of outbreeding?

Answer 17

hybrid vigor, or heterosis

Question 18

what is phenotypic similarity based on?

Answer 18

performance

Question 19

what is positive assortative mating?

Answer 19

mating a male and female because they resemble each other closely (for a trait) than if chosen at random from the population

Question 20

what is negative assortative/dissassortative mating?

Answer 20

mating a male and female because they resemble each other less closely (for a trait) than if chosen at random from the population

Question 21

what must be true in order for offspring to be considered inbred?

Answer 21

sire and dam must be genetically related

Question 22

what does Fx (inbreeding coefficient) measure?

Answer 22

the percent increase in homozygous gene pairs in the individual relative to the average of the breed

Question 23

what will the Fx value of most head of livestock not exceed?

Answer 23

0.5

Question 24

what does IBS mean?

Answer 24

identical by state, or by chance, no common ancestor

Question 25

what is the genetic result of inbreeding?

Answer 25

increase in homozygosity beyond what would be found in a randomly mating population

Question 26

what is linebreeding?

Answer 26

a less intense form of linebreeding to concentrate the genes of one common ancestor by mating individuals within a particular line, designed to maintain a high degree of relationship to a highly regarded ancestor

Question 27

where is linebreeding most commonly used?

Answer 27

the horse industry

Question 28

what are the 6 effects of inbreeding?

Answer 28

1. Prepotency
2. Expression of deleterious recessive alleles
3. Inbreeding depression
4. Tends to “fix” characteristics (traits) in a population
5. Concentrate genes in a population: can be good or bad
6. Increases probability of getting similar genes to offspring from ancestor

Question 29

describe prepotency

Answer 29

performance of offspring is especially like that of the parent

Question 30

does inbreeding create deleterious recessive alleles?

Answer 30

no, it just increases their expression

Question 31

describe inbreeding depression

Answer 31

acts of quantitative traits, is a decrease in the performance of inbreds for trait like fertility and survivability, the result of an unfavorable GCV

Question 32

what is additive genetic relationship?

Answer 32

the proportion of genes which 2 individuals have in common; describes the added genetic likeness of the 2 individuals in question, a numerical value from 0-1

Question 33

what does genetic relationship attempt to do?

Answer 33

quantify the proportion of genes within 2 individuals that are identical by descent

Question 34

what is the variable the represents genetic relationship?

Answer 34

Rxy