Flashcards in Lecture 2: Quantitative Genetics 1 Deck (11):
Define 'quantitative genetics'.
The study of the genetic and environmental components of traits that vary continuously.
Define 'qualitative traits' and give examples.
Difference between phenotypes of two individuals can be explained by the difference in genotype at a small number of loci i.e. 1 or two e.g. blood groups, cat coat colour, colour vision.
Define 'quantitative traits' and give examples.
Phenotypic difference between individuals is due to difference in genotype at a large number of loci e.g. weight, height.
What is the phenotypic variance dependent on?
Phenotypic variance = genetic variance + environmental variance.
What is genetic variance dependent on?
Genetic variance = additive genetic variance + dominance genetic variance + epistatic genetic variation.
What are the problems with predicting the evolution of quantitative traits?
- environmental effects.
Define 'heritability' and give its equation.
A measure of the degree of resemblance between relatives. H squared = additive genetic variance/ phenotypic variance. OR H squared = additive genetic variance/ (genetic variance + environmental variance).
What is the 'breeder's equation'?
R = h(squared) x S
R = response to selection
h = heritability
S = selection differential.
What is epistatic genetic variance?
Variation due to interactions among loci.
Define 'polygenetic inheritance'.
A trait is determined by a large number of different genes (resulting in high variation).