A stochastic model for speciation by mating preferences

TL;DR

This paper introduces a stochastic model demonstrating that even weak mating preferences can lead to reproductive isolation and speciation in subdivided populations, with results supported by stochastic and deterministic analyses.

Contribution

It presents a novel stochastic model showing how mating preferences alone can cause speciation, with robustness across various model generalizations.

Findings

Mating preferences induce reproductive isolation in subdivided populations.

Small mating preferences are sufficient for speciation.

The model's results are robust under various generalizations.

Abstract

Mechanisms leading to speciation are a major focus in evolutionary biology. In this paper, we present and study a stochastic model of population where individuals, with type a or A, are equivalent from ecological, demographical and spatial points of view, and differ only by their mating preference: two individuals with the same genotype have a higher probability to mate and produce a viable offspring. The population is subdivided in several patches and individuals may migrate between them. We show that mating preferences by themselves, even if they are very small, are enough to entail reproductive isolation between patches, and we provide the time needed for this isolation to occur as a function of the population size. Our results rely on a fine study of the stochastic process and of its deterministic limit in large population, which is given by a system of coupled nonlinear differential equations. Besides, we propose several generalisations of our model, and prove that our findings are robust for those generalisations.