BIOL 336 Lecture Notes - Lecture 14: Quantitative Genetics, Heritability
Document Summary
Breeder"s equation: the change (r) in the mean of a quantitative trait is equal to the mean among the breeding parents minus the mean among the whole pop (s) times the narrow sense heritability (h^2) **this h^2 has nothing to do with h, the dominance coefficient! When offspring are identical to parents, h2 = 1. Understanding breeder"s: imagine that each offspring is a clone of its single parent with no environmental effect example 1: parents: 40 kg, 60 kg, 80 kg (80 selected) offspring: all 3 are 80kg. S is the mean of the breeding adults minus the mean of whole population so s = 80-60kg = 20kg. S is 20kg and r = 20kg so h^2 must be 1. S = 80-60=20 (how we are picking or how environment is picking sheep breed) R =60-60 = 0 (what happens in response to picking) So far as we can see when genes vary but environment does not h2 = 1.
