Lecture 11 - Selecting Flashcards
how does the environment affect response to selection
it messes with your accuracy
when does a genotype by environment (GxE) interaction occur
when the relative performance of 2 genotypes changes according to the environment they are evaluated in
2 types of GxE interactions
-non-crossover interactions
- cross-over interactions
non-crossover GxE interaction
there is a change in relative performance of 2 genotypes, but there is no change in rank of performance 9relative performance has changed, rank has not)
GxE crossover interaction
there is a change in relative performance of 2 genotypes and their rank of performance has changed (both relative performance and rank has changed)
GxE selection implications
- genotypes with little G x E are considered to have wide adaptation
- crossover = more specific adaptations
- difficult to determine what caused the crossover interaction
- need to decide target market (broad or specific environment)
what does wide adaptation correlate with
more stability (less interaction with the environment)
how can we increase genetic gain
try to shorten the amount of time between cycles and varieties
indirect selection
improvement of 1 trait through selection for a correlated trait
what would cause 2 traits to be correlated trait
pleiotropy (genes are close together = genetic linkage)
genetic linkage
genes conferring phenotype are in close physical proximity on a chromosome which suppressed recombination (linkage disequilibrium)
pleiotrophy
one gene confers multiple phenotypes
reasons to use indirect selection
- trait x is very expensive to measure
- trait x is difficult to measure
- trait x is expressed very late in life cycle (after flowering or perennials)
is genomic selection direct or indirect phenotyping
indirect
