Heretability Flashcards
What is Vp?
The total variation within a population for a phenotype, measured by phenotypic variance
What are the two components of Vp?
Variation due to difference in genotype, Vg
Variation due to environmental effects, Ve
How do you calculate Vp?
Vg + Ve
What is H2 and how is it calculated?
Broard sense heritability, calculated by Vg/Vp
What is broad sense heritability?
The proportion of phenotypic variation in a population that is due to genetic differences among individuals
What happens to BSH if we increase genetic variance?
increase heritability, more phenotypic variability
Why is BSH only good for predicting short term response?
Allele frequencies change over time due to selection and genetic drift, which affects the genetic variation and in turn changes the heritability
What does broad sense heritability measure?
The genetic contribution to variation in a trait
How does natural selection act on quantitative traits?
heritable variation for that trait
competition for resources
Difference in fitness that depend on the trait
What is directional selection and what is its effect on Vg?
Shifts the overall population by favouring an extreme, genetic variation remains the same
What is stabilising selection and what is its effect on Vg?
Acts against extreme phenotypes, and causes decrease in genetic variation
What is disruptive selection and what is its effect on Vg?
Favours variants of opposable extremes, causes increase in genetic variation
How can natural selection act on quantitative traits?
when variation in a heritable trait is correlated with fitness
Why does artificial selection of quantitative traits reach plateau?
Because genetic variation runs out, or when natural selection acts against artificial selection
What is narrow sense heritability?
The proportion of variation that can be passed down to offspring
