How much change next generation average of population

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(How much change next generation) average of population relative number 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 relative number 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 define 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 define 2 parameters Response Differential change in population due to polygenic selection = R AVE (whole pop.in G=1) AVE (whole pop.in G=0) = = = - relative number 0 900 average of selected G=0 G=1 Parents 0 0 900 seed size (mg) Offspring 692 R average = 404 average = 609 relative number 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 PERFECT 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
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