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Lecture 5 - Top 12 warmest years since 1880 are very recent...

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Top 12 warmest years since 1880 are very recent years. Guppy Experiment Results High predation favors smaller size and faster maturity Age at maturity evolved up to 3 % per generation Size evolved up to 1% per generation 11 years -19 guppy generations Quantifying selection: Fitness- the number of descendant zygotes produced by an individual, phenotype or genotype. Components of fitness Zygotes Juveniles selection on viability Juveniles adults mating Adults gametes fecundity Gametes zygotes compatibility Absolute fitness W=number of progeny produced =probability of survival x fecundity Mean population fitness = avg abs fitness Relative fitness w=W/W(mean) W<1 less better The strength on selection depends on relative fitness How fast is evolution by nat selection? The spread of an advantageous mutation Genotype: aa Aa AA Relative fitness : 1 1+s 1+2s The change in allele frequency Δ p= p(1-p)s P=current frequency S=selection coefficient What its frequency will be in the next generation If we know frequency of A p=0.5 Relative fitness 1-1.1-1.2 So s=0.1 0.5(1-0.5)0.1= S=measure of the strength of selection p(1-p)= the genetic variance The rate of evolution is = the genetic variance x strength of selection
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Graph: Frequency of A vs generations S=0.001 S curve S=o.o1 very steep ..evolution very fast
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