lec_5_cond_13

# In this case indicating that natural selection was

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- in this case indicating that natural selection was operating via the protective effect of the Δ CCR5 allele. 20 (K = 1 in asexual organisms) Next we will extend this definition to the fitness of different genotypes and alleles

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If you worked 40% of the time: 2.5/2.5 = 1 example Genotype A 1 A 1 s ij 0.2 f ij 20 W* ij 2 A 1 A 2 0.1 20 1 A 2 A 2 0.5 10 Relative Fitness (A i A j ) = Fitness (W* ij ) Maximum Fitness (W* ij ) = W ij W ij 2/2.5 = 0.8 2.5 1/2.5 = 0.4 1/2 1/2 1/2 Individual Fitness = W* = number of genome copies an individual leaves in the next generation. prop(A2) = q prop(A1) = p (we will use this symbol later for Δ CCR5) Two competing alleles, A 1 and A 2 Three competing genotypes, A 1 A 1 A 1 A 2 A 2 A 2 Fitness (A i A j ) = W*(A i A j ) = W* ij = average number of genome copies an individual of a specified genotype leave in the next generation. REVIEW: Relative Fitness (A i A j ) = W(A i A j ) = W ij = Fitness (A i A j ) / MAX {Fitness (A i A j )} Suppose that you are a member of a rock band 1) When you play you make \$1,000.00 / night 2) When you don’t you make \$ 10.0 / night Suppose that you play 10% of nights, (so you don’t play 90% of the nights) average daily pay = 10% you work 0.1 (\$1,000.00) 90% you don’t 0.9 (\$10.00) = average daily pay = 40% you work 0.4 (\$1,000.00) 60% you don’t 0.60 (\$10.00) Net Pay Net Pay Net Pay relative weight relative weight relative weight relative weight 21 selling news papers \$100/day + \$9/day \$109/day = = \$400/day + \$6/day \$406/day = Concept of a weighted mean The standard equation of natural selection if we use the concept of a weighted average: Δ p = p ( - 1 ) w 1 w Frequency of ! CCR5 ( p ) 0.1 0.2 0.3 Generation 0 1 2 3 4 5 How much change? Relative fitness is the metric used in all of the models of natural selection
More generally, Play Do not Play proportion pay/day (\$) p X q Y Then, Average pay/day = weighted average pay = p (X) + q(Y) So the fitness of the A1 allele is a weighted average based on the relative frequencies of its partners.

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