Quantitative genetics

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Chapter 7 Quantitative Genetics

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Presentation transcript:

Quantitative genetics

Continuous traits have a complex genetic basis Polygenic trait: influenced by many genetic loci Interaction between alleles (epistasis) Interaction with environment (phenotypic plasticity) Quantitative genetics: study of the genetic mechanisms of continuous phenotypic traits

Hardy-Weinberg extended to polygenic traits

Complex traits vary continuously

Components of phenotypic variation VP = VG + VE Total phenotypic variance in population Variance due to genetic differences Variance due to environmental differences

Genetic and environmental influences create continuous distribution

How we measure heritability Slope = heritability

The effects of selection can be large

STRONG VS. WEAK SELECTION

RELATIONSHIP BETWEEN Selection and heritability R = h2 x S Selection can be strong, but response also depends on heritability!

To remember: Evolution and selection are not the same Selection can occur without evolution (Evolution also occurs without selection) The magnitude of selective evolutionary change depends on: Strength of selection (selection differential) Heritability