Rare events in population genetics: Stochastic tunneling in a two-locus model with recombination

Abstract

We study the evolution of a population in a two-locus genotype space, in which the negative effects of two single mutations are overcompensated in a high fitness double mutant. We discuss how the interplay of finite population size, $N$, and sexual recombination at rate $r$ affects the escape times $t_{\mathrm{esc}}$ to the double mutant. For small populations demographic noise generates massive fluctuations in $t_{\mathrm{esc}}$. The mean escape time varies non-monotonically with $r$, and grows exponentially as $\ln t_{\mathrm{esc}}\sim N(r-r^{\ast }{)}^{3/2}$ beyond a critical value $r^{\ast }$.

4 pages, 3 figures

References in corpus (2)

• Extinction of metastable stochastic populations
• The pace of evolution across fitness valleys

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