F13 lecture 13

# 5 vd 2pqd2 by definition terms are squared because

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Unformatted text preview: s greater in the bb background, overall effect of C locus is greater in the bb background for a single locus •  we can use p, q, a, and d to determine how the popula2on mean is aﬀected by these factors and vice versa –  possible for mul2ple loci but beyond the scope –  without epistasis, results of mul2ple loci can be summed mean is determined as a deviation from the midpoint of the two heterozygotes population means are determined by: • allele frequencies • magnitude of additive effect (a) • degree of dominance (d) exercise •  assume p=q=0.5 •  phenotypes: AA 15 Aa 9 aa 8 midpoint of homozygotes is 8 + (15- 8)/2 = 11.5 a = 3.5, d = - 2.5 G = a(p- q) + 2pqd = 3.5(0) + 2(.5)(.5)(- 2.5) =- 2 on devia2on scale =9.5 on trait (absolute value) scale popula2on variance • we’ve used this already • numerator = sum of squares (SS) (sum of squared deviations from the mean) • denominator is also the degrees of freedom • overall this is an estimate of the average squared deviation from the mean • sometimes called “mean square” (MS) conceptual variance breakdown •  VP = VG + VE •  VG = VA + VD +...
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