lec_6_cond_13

# How much change next generation average of population

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(How much change next generation) average of population 0 0 average of selected G=0 G=1 900 692 0 0 900 seed size (mg) average of population 404 average = 404 average = 692 average of selected G=0 G=1 Parents average of population Observed Results 0 0 900 average = 404 692 0 0 900 seed size (mg) Offspring average is in between 404 & 692 average = 609 So response to selection depends on how much phenotypic variation is due to genetic variation among individuals, i.e. heritability average seed size increased by 51% To predict future change in response to selection we need to estimate heritability. Note: The symbol for heritability is h 2 not h, so h 2 is not heritability squared 27

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R S 692 - 404 = 288 R=609-404=205 S=692-404=288 609 - 404 = 205 relative number 0 G=0 G=1 0 0 900 seed size (mg) average = 609 To estimate heritability, we need to defne 2 parameters Selection DiFFerential = strength oF polygenic selection = AVE(selected) - AVE(whole pop) = S average oF selected Parents OFFspring 900 average = 404 692 S = To estimate heritability, we need to defne 2 parameters Response DiFFerential change in population due to polygenic selection = R AVE (whole pop.in G=1) AVE (whole pop.in G=0) = = = - 0 900 average oF selected G=0 G=1 Parents 0 0 900 seed size (mg) OFFspring 692 R average = 404 average = 609 0 900 average = 404 692 G=0 G=1 Parents 0 0 900 seed size (mg) average = 609 OFFspring Realized heritability = proportion oF polygenic selection that is maniFest in oFFspring = R / S = estimate oF heritability (h 2 ) 205 288 = 205 / 288 = 0.71 Realized heritability can be expressed as a slope with Family data slope = 1 is PER±ECT heritability slope = 0 is NO heritability Intermediate heritability Average phenotype oF oFFspring Average phenotype oF parents 28 The slope oF the average phenotype oF parents vs. the average phenotype oF their Family (oFFspring) is another way to estimate h 2 Selection Response to selection Selection & Response Average
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