Mutation Accumulation in a Selfing Population: Consequences of Different Mutation Rates between Selfers and Outcrossers

Shin-Ichiro Nakayama,Masaki Tateno,K Ryo Takahasi,Shoi Shi,Masakazu Shimada,Art F Y Poon

doi:10.1371/journal.pone.0033541

Shin-Ichiro Nakayama, Masaki Tateno + Show 4 more

Open Access

https://doi.org/10.1371/journal.pone.0033541

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Abstract

Currently existing theories predict that because deleterious mutations accumulate at a higher rate, selfing populations suffer from more intense genetic degradation relative to outcrossing populations. This prediction may not always be true when we consider a potential difference in deleterious mutation rate between selfers and outcrossers. By analyzing the evolutionary stability of selfing and outcrossing in an infinite population, we found that the genome-wide deleterious mutation rate would be lower in selfing than in outcrossing organisms. When this difference in mutation rate was included in simulations, we found that in a small population, mutations accumulated more slowly under selfing rather than outcrossing. This result suggests that under frequent and intense bottlenecks, a selfing population may have a lower risk of genetic extinction than an outcrossing population.

Highlights

A large part of spontaneous mutations are deleterious [1], which tend to accumulate continuously in a small population
The mean extent of inbreeding depression was obtained analytically and by simulations [9], which indicated that the deleterious mutation rate, as well as the intensity of selection against deleterious alleles, affects the extent of inbreeding depression
We further found that the range of population size leading to slower mutation accumulation in a selfing population was wider when slight outcrossing was performed, and when the strength of selection was reduced (Figure 3)

Summary

Introduction

A large part of spontaneous mutations are deleterious [1], which tend to accumulate continuously in a small population. Analytical model To elucidate the effect of different mutation rates on the level of inbreeding depression, and further to determine the conditions under which selfing and outcrossing become evolutionarily stable, we first investigated the general model analytically by assuming an infinite population (N = ‘) and an infinite number of loci (L = ‘).

Results

Conclusion