Exam 5 Flashcards
What is meant by “correlated response to selection”
Change in a BV for a trait that is genetically correlated with a trait under selection
Phenotypic correlation
Strength and direction of relationship between 2 phenotypes
Genetic correlation
Strength and direction of relationship between BV for 2 traits
Environmental correlation
Strength and direction of the relationship between environmental effects for 2 traits
Economically Relevant Trait (ERT)
A trait that directly makes you money or is important to you
What is an indicator trait? Provide an example
Trait that by itself is not important, but is genetically correlated with an ERT: SCS predicts incidence of mastitis in dairy cows
Three reasons why indirect selection on an indicator is preferable to direct selection on an ERT?
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
What causes genetic correlations (2 answers)
Pleiotropy and Linkage
Define pleiotropy
Single gene that affects more than 1 trait
What is the main consequence of multiple trait selection in comparison to single trait selection?
As you add more traits the selection intensity for each trait will go down
Three methods of multiple trait selection and their rate of genetic change
Tandom Selection = slowest
Independent Culling Levels (ICL) = middle
Selection index = Fastest
define inbreeding depression
A decrease in performance resulting from inbreeding
What are two strategies that can be used to reduce the effects of inbreeding depression in a herd
Crossbreeding and Outbreeding
Inbreeding coefficient (Fx)
Percent of loci in an animal that are identical by descent
Relationship coefficient (Rsp)
An allele at the same locus that are identical by descent between 2 individuals
