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Haldane, J. B. (1937). The effect of variation of fitness. The American Naturalist, 71(735), 337-349.
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Abstract: In a species in equilibrium variation is mainly due to two causes. Some deleterious genes are being weeded out by selection at the same rate as they are produced by mutation. Others are preserved because the heterozygous form is fitter than either homozygote. In the former case the loss of fitness in the species is roughly equal to the sum of all mutation rates and is probably of the order of 5 per cent. It is suggested that this loss of fitness is the price paid by a species for its capacity for further evolution.
Notes
Symbols
- $\mu$ is the mutation rate per locus per generation.
- $N$ is the population size.
- $x$ is the mutant allele frequency.
- $f$ is the relative average fitness of individuals carrying the mutant allele.
A fraction of the unmutated loci are expected to mutate each generation.
$$N\mu (1-x)$$
Mutated copies are removed by selection each generation ($1-f$ survive).
$$N x (1-f) $$
