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A coarse-grained biophysical model of sequence evolution and the population size dependence of the speciation rate.

Khatri, BS; Goldstein, RA; (2015) A coarse-grained biophysical model of sequence evolution and the population size dependence of the speciation rate. J Theor Biol , 378 pp. 56-64. 10.1016/j.jtbi.2015.04.027. Green open access

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Abstract

Speciation is fundamental to understanding the huge diversity of life on Earth. Although still controversial, empirical evidence suggests that the rate of speciation is larger for smaller populations. Here, we explore a biophysical model of speciation by developing a simple coarse-grained theory of transcription factor-DNA binding and how their co-evolution in two geographically isolated lineages leads to incompatibilities. To develop a tractable analytical theory, we derive a Smoluchowski equation for the dynamics of binding energy evolution that accounts for the fact that natural selection acts on phenotypes, but variation arises from mutations in sequences; the Smoluchowski equation includes selection due to both gradients in fitness and gradients in sequence entropy, which is the logarithm of the number of sequences that correspond to a particular binding energy. This simple consideration predicts that smaller populations develop incompatibilities more quickly in the weak mutation regime; this trend arises as sequence entropy poises smaller populations closer to incompatible regions of phenotype space. These results suggest that a generic coarse-grained approach to evolutionary stochastic dynamics allows realistic modelling at the phenotypic level.

Type: Article
Title: A coarse-grained biophysical model of sequence evolution and the population size dependence of the speciation rate.
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.jtbi.2015.04.027
Publisher version: http://dx.doi.org/10.1016/j.jtbi.2015.04.027
Additional information: Copyright © 2015 The Authors.Published by Elsevier Ltd.This is an open access article under the CCBY license (http://creativecommons.org/licenses/by/4.0/).
Keywords: Dobzhansky Muller incompatibilities, Evolution, Free fitness, Genotype phenotype map, Sequence entropy
UCL classification: UCL
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Infection and Immunity
URI: https://discovery.ucl.ac.uk/id/eprint/1468805
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