Exam 4 Flashcards
Indicator Trait
A trait that may or may not be of importance itself, but is used as a means of selecting a genetically correlated trait
Economic Weight
The change in return expected from a one unit change in performance of a trait
Breeding Objective
The weighted combination of traits defining aggregate breeding value for use in a selection index
Marker Assisted Selection
A type of indirect selection in which selection is on specific DNA sequences
Single Trait Selection
Selection for one trait
Tandem Selection
Selection for first one trait, then another
Multiple Trait Selection
selection for more than one trait
Selection Target
A level of breeding value that is optimal in either the absolute or practical sense
Environmental Correlation
A measure of the strength of the relationship between environmental effects on two traits
Phenotypic Correlation
A measure of the strength of the relationship between performance values for two traits
Genetic Correlation
A measure of the strength of the relationship between breeding values for two traits
Effective Proportion Saved
Reflects correct selection intensity when selecting for multiple, uncorrelated traits
Aggregate Breeding Value
The breeding value of an individual for a combination of traits
Pleiotropy
Same gene(s) affecting more than one trait
Economic Selection Index
A combination of weighing factors and genetic information on multiple traits
Independent Culling Levels
Minimum standards for traits under selection with individuals failing to meet a single criterion not selected regardless of merit in other traits
Direct Response
Genetic change in a trait resulting from selection for that trait
Correlated Response
Genetic change in one or more traits resulting from selection for another trait
QTL
Quantitative Trait Locus
Categories of traits for which marker assisted selection is expected to be useful
Carcass Traits
Sex-limited Traits
Two causes of genetic correlations? Specify permanent or temporary cause
Pleiotropy- same gene affects both traits (permanent)
Linkage- genes affects different traits, but are close on chromosome (temporary)
Briefly define each direct response to selection and correlated response to selection.
Direct Response: changing 1 trait by selecting on that trait (selecting x to change x).
Correlated Response: changing 1 trait by selecting on a different trait (selecting x to change y)
Briefly define each direct response to selection and correlated response to selection.
Direct Response: changing 1 trait by selecting on that trait (selecting x to change x).
Correlated Response: changing 1 trait by selecting on a different trait (selecting x to change y)
Provide one example of when correlated response would be considered beneficial. Provide another example where correlated response would be a concern. Use specific traits for examples.
Beneficial: increasing scrotal size in bulls decreases puberty age in daughters
Concern: increasing yearling and weaning weights would increase birth weights which could cause calving difficulties




