Exam 5

Question 1

What is meant by “correlated response to selection”

Answer 1

Change in a BV for a trait that is genetically correlated with a trait under selection

Question 2

Phenotypic correlation

Answer 2

Strength and direction of relationship between 2 phenotypes

Question 3

Genetic correlation

Answer 3

Strength and direction of relationship between BV for 2 traits

Question 4

Environmental correlation

Answer 4

Strength and direction of the relationship between environmental effects for 2 traits

Question 5

Economically Relevant Trait (ERT)

Answer 5

A trait that directly makes you money or is important to you

Question 6

What is an indicator trait? Provide an example

Answer 6

Trait that by itself is not important, but is genetically correlated with an ERT: SCS predicts incidence of mastitis in dairy cows

Question 7

Three reasons why indirect selection on an indicator is preferable to direct selection on an ERT?

Answer 7

1) Indicator trait is cheaper to measure, easier to measure, or can be measured earlier in life
2) Increases selection accuracy
3) Increases selection intensity

Question 8

What causes genetic correlations (2 answers)

Answer 8

Pleiotropy and Linkage

Question 9

Define pleiotropy

Answer 9

Single gene that affects more than 1 trait

Question 10

What is the main consequence of multiple trait selection in comparison to single trait selection?

Answer 10

As you add more traits the selection intensity for each trait will go down

Question 11

Three methods of multiple trait selection and their rate of genetic change

Answer 11

Tandom Selection = slowest
Independent Culling Levels (ICL) = middle
Selection index = Fastest

Question 12

define inbreeding depression

Answer 12

A decrease in performance resulting from inbreeding

Question 13

What are two strategies that can be used to reduce the effects of inbreeding depression in a herd

Answer 13

Crossbreeding and Outbreeding

Question 14

Inbreeding coefficient (Fx)

Answer 14

Percent of loci in an animal that are identical by descent

Question 15

Relationship coefficient (Rsp)

Answer 15

An allele at the same locus that are identical by descent between 2 individuals

Question 16

Identical by descent

Answer 16

Allele (A) derived by the same common ancestor

Question 17

Identical by state

Answer 17

Alleles are the same (AA) also by descent

Question 18

If two alleles at a locus are identical by descent it means:

Answer 18

Derived from the same common ancestor