Heritability Flashcards
Why are many phenotypic traits continuous?
Often multiple genes affect a trait. As the number of loci increase, phenotypic frequency distribution becomes increasingly continuous. Environmental effects also play a role.
What is quantitative genetics?
The area of study concerned with the inheritance of quantitative differences between individuals.
What are polygenic characters?
Characters influenced by many genes.
What are the 2 components of phenotypic variance (VP)?
The genotypic component (VG) and the environmental component (VE).
What is the reaction norm?
The set of phenotypes produced by a given genotype across 2+ environments.
What is the common garden experiment?
Grow all plants in the same environmental conditions so there is no environmental variation. Any observed variation must therefore be genetic.
What makes up Ve?
The pure environment (VE) and the interaction component (VGxE).
What makes up Vg?
Made up of additive variance (Va) - many genes of small additive effect - and non-additive variance.
What makes up non-additive variance?
Dominance (Vd) and epistasis (Ve).
What is epistasis?
Interactions among genes.
Define broad sense heritability (H2).
Proportion of phenotypic variation among individuals in a population that is due to genetic variation.
What does it mean if broad sense heritability (H2) equals 0?
All variability observed in a trait in a given population is due to environmental differences experienced among individuals.
What does it mean if broad sense heritability (H2) equals 1?
All variability observed in a trait in a given population is due to genetic differences among individuals.
Define narrow sense heritability (h2).
Proportion of phenotypic variation among individuals in a population that is due to additive genetic variation.
What is additive variance?
The fraction of the genetic variation transmitted from parent to offspring. A measure of how well a trait will respond to selective breeding.
