Lecture 13 Flashcards
(13 cards)
What does the rate at which a population can respond to selection depend on?
- strength of selection (S)
- heritability (h^2) or the proportion of variation that is due to additive gene effects
How can the response to selection be measured?
the response can be measured in the change in the mean phenotype of the population
How do we calculate the evolutionary response to directional selection?
R=h^2 x S
R= response to selection
h^2=heritability
S=strength of selection
What is the cummulative effects of long term selection?
long term selection may eventually exhaust additive genetic variation. so we would just keep on getting the same thing, since there is no longer additive genetic variation for the trait, so any differences in the plants would be due to environmental differences/influences
What happens when you lose variation in a trait?
you lose heritability
When you have low heritability is Va big or small
small
what is the strength of selection caused by: within or between generation?
this change is caused by differences within a generation
how do we calculate S?
S=mean of selected parents - mean of whole population
what is the selection differential
the difference between the mean phenotypes of the selecteed parents and the entire population
is the response to selectin within or between a generation
between generations
What is the response to selection?
the difference between the mean phenotypes of offspring generation and the original population
offspring gen - original pop= R
What does the relative change in mean phenotype from one generation to the next equal?
equals the proportion of total phenotypic variation associated with additive genetic effects (what is heritable)
what does high heritability result in?
high heritability results in larger change
