Blackwell Publishing

Multi-locus population genetics - How does selection alter haplotype frequencies?


Additive fitness

Imagine that two loci encode two digestive enzymes. The enzyme produced by the A locus digests one kind of food, that by the B locus another kind of food. The genotypes might enable a certain number of joules of energy to be obtained by feeding in a particular environment:

A1/A1 A1/A2 A2/A2 B1/B1 B1/B2 B2/B2

energy obtained: w11 w12 w22 x11 x12 x22

The fitness of an individual might be proportional to the total energy it obtains by feeding; its fitness for the two loci would then be found by adding those of its two genotypes together:

A1/A1 A1/A2 A2/A2
B1/B1w11+x11w12+x11 w22+x11
B1/B2w11+x12 w12+x12 w22+x 12
B2/B2w11+x22 w12+x22 w22+x22

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