Population Genetics: Heritability & Complex Traits Flashcards

A set of vocabulary flashcards covering the concepts, formulas, and methods of determining heritability in population genetics as discussed by Dr. Queiroga.

Heritability

The proportion of total phenotypic variance ($V_p$) in a population attributable to genetic variation ($V_G$), ranging from 0 to 1.

Broad-sense Heritability ($H^2$)

The proportion of phenotypic variance including all genetic effects: additive, dominance, and interaction (epistatic) variances ($H^2 = V_G / V_p$).

Narrow-sense Heritability ($h^2$)

Measures the proportion of variance due solely to additive genetic variance ($V_A$). It determines the rate of response to selection ($R = h^2 S$).

Additive Genetic Variance ($V_A$)

The specific genetic component or "breeding value" that is passed down to offspring, used to calculate narrow-sense heritability.

Falconer’s Formula

A formula used in twin studies to estimate broad-sense heritability: $H^2 = 2(r_{MZ} - r_{DZ})$.

$$r_{MZ}$$

The correlation coefficient of a trait between identical (Monozygotic) twins.

$$r_{DZ}$$

The correlation coefficient of a trait between fraternal (Dizygotic) twins.

Monozygotic (MZ) twins

Twins who share 100% of their genes, often used in studies to estimate genetic components of traits.

Dizygotic (DZ) twins

Twins who share approximately 50% of their genes, serving as a comparison group to identical twins.

Mid-parent value

The average trait value of the parents, plotted against the trait value of offspring in a regression to determine narrow-sense heritability.

Slope $b$

In a regression of offspring on mid-parent values, this value is equal to the narrow-sense heritability ($h^2$).

Realized Heritability

A measure of how a population responds to artificial selection, calculated using the Breeder's Equation.

Breeder's Equation

A formula used to calculate heritability or response to selection: h^2 = rac{R}{S}.

Selection Differential ($S$)

The difference between the mean of the selected parents and the mean of the original population.

Response to Selection ($R$)

The difference between the mean of the offspring and the mean of the original population.