The reduction in fixation probability caused by substitutions at linked loci

N.H. Barton, Genetical Research 64 (1994) 199–208.

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Abstract
The probability of fixation of a mutation with selective advantage s will be reduced by substitutions at other loci. The effect of a single substitution, with selective advantage S0016672300032857inline1, can be approximated as a sudden reduction in the frequency of the favourable allele, by a fraction w = 1 −(s/S)r/s (where r is the recombination rate). An expression for the effect of a given sequence of such catastrophes is derived. This also applies to the ecological prxoblem of finding the probability that a small population will survive, despite occasional disasters. It is shown that if substitutions occur at a rate Δ, and are scattered randomly over a genetic map of length R, then an allele is unlikely to be fixed if its advantage is less than a critical value, Scrit = (π2/6)(2ΔS/(Rlog(S/s))). This threshold depends primarily on the variance in fitness per unit map length dueto substitutions, var(W)/R = 2ΔS/R. With no recombination, the fixation probability can be calculated for a finite population. If Δ > s, it is of the same order as for a neutral allele ( ≈ Δ/(2N(Δ−s))), whilst if S0016672300032857inline2, fixation probability is much higher than for a neutral allele, but much lower than in the absence of hitch-hiking S0016672300032857inline3. These results suggest that hitch-hiking may substantially impede the accumulation of weakly favoured adaptations.
Publishing Year
Date Published
1994-12-01
Journal Title
Genetical Research
Volume
64
Issue
3
Page
199 - 208
IST-REx-ID

Cite this

Barton NH. The reduction in fixation probability caused by substitutions at linked loci. Genetical Research. 1994;64(3):199-208. doi:10.1017/S0016672300032857
Barton, N. H. (1994). The reduction in fixation probability caused by substitutions at linked loci. Genetical Research, 64(3), 199–208. https://doi.org/10.1017/S0016672300032857
Barton, Nicholas H. “The Reduction in Fixation Probability Caused by Substitutions at Linked Loci.” Genetical Research 64, no. 3 (1994): 199–208. https://doi.org/10.1017/S0016672300032857 .
N. H. Barton, “The reduction in fixation probability caused by substitutions at linked loci,” Genetical Research, vol. 64, no. 3, pp. 199–208, 1994.
Barton NH. 1994. The reduction in fixation probability caused by substitutions at linked loci. Genetical Research. 64(3), 199–208.
Barton, Nicholas H. “The Reduction in Fixation Probability Caused by Substitutions at Linked Loci.” Genetical Research, vol. 64, no. 3, Cambridge University Press, 1994, pp. 199–208, doi:10.1017/S0016672300032857 .

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