Ecology 3

quantitative genetics - the scientific study of the statistical analysis of the effects that heredity and environment have on phenotypic variation

• selection differential (s)
• selection gradient (B) "beta"

• -describes the strength of selection relative to the distribution or variance of the phenotypic trait
• -difference in mean phenotype between the population as a whole and the selected parents of the next generation

the proportion of phenotypic variation in a population that is attributable to genetic variation among individuals

• the regression slope of "fitness" estimate on phenotype
• used more in ecological studies because it's easier to measure in the field

the change in mean phenotype between parental generation before selection, and offspring generation (before selection on it, after selection on parental generation)

• R = h² S
• R = V_A B"beta"

• additive genetic variance
• passed on from parents to offspring, as sum of 2 alleles effects, one from mom, one from dad

• total phenotypic variance
• S² phenotypes
• V_P = V_G + V_E

• h² = V_A / V_P
• h² = 0,1, or inbetween, if so R<S

• measure of dispersion about a mean or average
• the standard deviation squared

• genetic variance
• V_G = V_A (additive) + V_D (dominance - interation between alleles within a gene) + V_i (interaction among genes, gene networks)
• **selection only responds to V_A

• epistasis
• interaction among genes, gene networks

environmental variance

• H² = V_G / V_P
• reflects all possible genetic contributions

the specific location of a gene or DNA sequence on a chromosome