Distribution of the fittest individuals and the rate of Muller's ratchet in a model with overlapping generations

Metzger, J.J.; Eule, S.

Distribution of the fittest individuals and the rate of Muller's ratchet in a model with overlapping generations

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Item Type:	Article
Title:	Distribution of the fittest individuals and the rate of Muller's ratchet in a model with overlapping generations
Creators Name:	Metzger, J.J. and Eule, S.
Abstract:	Muller's ratchet is a paradigmatic model for the accumulation of deleterious mutations in a population of finite size. A click of the ratchet occurs when all individuals with the least number of deleterious mutations are lost irreversibly due to a stochastic fluctuation. In spite of the simplicity of the model, a quantitative understanding of the process remains an open challenge. In contrast to previous works, we here study a Moran model of the ratchet with overlapping generations. Employing an approximation which describes the fittest individuals as one class and the rest as a second class, we obtain closed analytical expressions of the ratchet rate in the rare clicking regime. As a click in this regime is caused by a rare, large fluctuation from a metastable state, we do not resort to a diffusion approximation but apply an approximation scheme which is especially well suited to describe extinction events from metastable states. This method also allows for a derivation of expressions for the quasi-stationary distribution of the fittest class. Additionally, we confirm numerically that the formulation with overlapping generations leads to the same results as the diffusion approximation and the corresponding Wright-Fisher model with non-overlapping generations.
Keywords:	Computational Biology, Genetic Fitness, Genetic Models, Genetic Selection, Molecular Evolution, Mutation
Source:	PLoS Computational Biology
ISSN:	1553-734X
Publisher:	Public Library of Science
Volume:	9
Number:	11
Page Range:	e1003303
Date:	November 2013
Official Publication:	https://doi.org/10.1371/journal.pcbi.1003303
PubMed:	View item in PubMed

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