Mating Systems and Inbreeding

Question 1

Mating Systems (Overview)

Answer 1

Brings about population improvement

Random vs Non-random

Question 2

Random Mating System

Answer 2

Hardy-Weinberg can work
Genotypic frequencies dependent upon allelic frequencies

No attempt from breeder to pair specific mates

Question 3

Non-Random Mating Systems

Answer 3

Strategies for genetic change (2)

Expected proportion of homozygous and heterozygous individuals deviate from HW expectations

Question 4

Two Genetic Change Strategies

Answer 4

Selection and Mating Systems

Question 5

Selection

Answer 5

Decide which individuals to retain as parents and which genes will be passed to subsequent generations

Question 6

Goal of Selection

Answer 6

Higher frequencies of alleles with desired affect and lower freq. of alleles with undesirable affect

Question 7

Mating Systems (In relation to genetic strategies)

Answer 7

Which males mate with which females
No further changes in allelic freq. beyond selection
But is does alter genotypic frequencies

Question 8

Non-Random Mating

Answer 8

Assignment of mates based on Genetic relationship and Phenotypic similarities

Question 9

Genetic relationship

Answer 9

Based on pedigree
Not randomly selected
Males and females mated together: more close relation -> inbreeding
less close relation -> outbreeding

Question 10

Inbreeding

Answer 10

minimized as much as possible
Attempt to make individuals more homozygous for a gene from common ancestor

Question 11

Inbreeding coefficient

Answer 11

Probability that 2 alleles at a locus in an individual are identical by decent (coming from ancestor)
Represented by [Fx]

Question 12

Outbreeding

Answer 12

Increase heterozygosity
Hybrid vigor
Used in meat animal production a lot

Question 13

Phenotypic similarity

Answer 13

Based on performance
Mate males with females because:
Positive assortative mating and negative assortative mating

Question 14

Positive assortative mating

Answer 14

Resemble one another more closely

Question 15

Negative assortative mating

Answer 15

Resemble one another less closely

Question 16

Correlations between topics
(for mating systems)

Answer 16

Inbreeding and positive assortative mating -> increase homozygosity

Outbreeding and negative assortative mating -> increase heterozygosity

Question 17

Arrow diagrams

Answer 17

Individuals only appear once, but can trace common ancestor to descendants
Flow of genes through time

Question 18

Common Ancestor

Answer 18

In general - common for more than one individual on arrow diagram/pedigree

Question 19

Identical by decent

Answer 19

If S and D have a common ancestor and both possess identical copies of A’s gene
And if X inherits both copies from S and D, X would be homozygous for that gene and that gene would be IBD

Question 20

Linebreeding

Answer 20

Less intense form of inbreeding
Concentration of ancestral traits
Mating individuals within particular line

Question 21

Effects of inbreeding

Answer 21

• Prepotency
• Expression of deleterious recessive traits
• Inbreeding depression
• Tends to “fix” traits in population
• Concentrate genes
• Increasing probability of getting similiar genes to offspring from ancestor

Question 22

Prepotency

Answer 22

Performance of offspring is especially like that of the parent
Attempt to make individuals more homozygous for superior genes

Question 23

Expression of deleterious recessive traits

Answer 23

Gives inbreeding a bad reputation
Does not create deleterious recessive traits but can expose them

Question 24

Inbreeding Depression

Answer 24

decline in performance (such as fertility or survival)
Deals with Qualitative traits/Polygenetic traits
Unfavorable gene combination value

Question 25

Tend to “fix” traits in a population

Answer 25

Becomes identifiable

Question 26

Concentrates genes

Answer 26

Can be good or bad