assignment 3 solution


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Unformatted text preview: n is the mean fitness as determined by all loci, and u is the average mutaKon rate € over all loci, and n is the number of loci. •  See page 215 for the derivaKon of the drop in mean fitness due to the load across all loci: w n ≅ 1 − Ln ≅ 1− U U – the number of deleterious mutaKons per zygote •  EsKmates from primates (Eyre‐Walker and Keightley) were found to be surprisingly high •  In order to avoid accumulaKon of deleterious mutaKons, every new mutaKon must be eliminated by geneKc death (or a failure to reproduce) •  If U = 3, as esKmated for humans in one study, then each individual must suffer three geneKc deaths if the populaKon is to avoid meltdown! •  Something is clearly wrong… SynergisKc Epistasis •  EsKmates of U suggest that mean fitness of populaKons is much lower (even negaKve – see p. 214!) than reality •  This is probably because our assumpKon of mulKplicaKve interacKons is unrealisKc •  Kimura and Maruyama (1966) suggested the idea of ‘synergisKc epistasis’ to understand how deleterious mutaKons interact to impact organismal fitness •  Under their model, each deleterious mutaKon has an impact on fitness which is greater than the previous mutaKon (e.g. effect on fitness increases exponenKally) •  Thu...
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This note was uploaded on 11/20/2012 for the course BIO bio3124 taught by Professor Rezanokhbeh during the Spring '11 term at University of Ottawa.

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