Blackwell Publishing

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


Multiplicative fitness

One of the simplest two locus models is multiplicative. In this model, an individual's fitness for its two genotypes is found by multiplying the fitnesses of each of its one locus genotypes.

Suppose, for example, that the A locus influences survival from age 1-6 months, such that

A1/A1 A1/A2 A2/A2

survival chance1-6 months:
w11 w12 w22

and the B locus influences survival from ages 6 - 12 months:

B1/B1 B1/B2 B2/B2

survival chance 6-12 months:
x11 x12 x22

The total chance of surviving from age 1 - 12 months would then be the product of the two genotypes that an individual possessed: an individual with the haplotypes A1/A1B1/B2 would have a chance of survival of w11x12

An individual with the genotype A1/A1 therefore has a chance of surviving from age 1 - 6 months of w11 whether its genotype at the other locus is B1/B1, B1/B2, or B2/B2. The genotypes are independent: the effect of one genotype on survival is independent of the other locus.

Previous Next