Impact of the horizontal gene transfer on the evolutionary equilibria of a population

TL;DR

This paper models how horizontal gene transfer influences the evolutionary equilibrium of phenotypic distributions in asexual populations, revealing conditions for polymorphic states driven by the interplay of transfer, mutation, and selection.

Contribution

It introduces a mathematical model incorporating horizontal gene transfer into evolutionary dynamics, showing its role in maintaining phenotypic diversity unlike models without transfer.

Findings

Polymorphic equilibria can exist under certain parameter ranges.

Horizontal gene transfer promotes phenotypic diversity.

Models neglecting transfer tend to predict monomorphic populations.

Abstract

How does the interplay between selection, mutation and horizontal gene transfer modify the phenotypic distribution of a bacterial or cell population? While horizontal gene transfer, which corresponds to the exchange of genetic material between individuals, has a major role in the adaptation of many organisms, its impact on the phenotypic density of populations is not yet fully understood. We study an elliptic integro-differential equation describing the evolutionary equilibrium of the phenotypic density of an asexual population. In a regime of small mutational variance, we characterize the solution which results from the balance between competition for a resource, mutation and horizontal gene transfer. We show that in a certain range of parameters polymorphic equilibria exist, which means that the phenotypic density may concentrate around several dominant traits. Such polymorphic equilibria result from an antagonist interplay between horizontal gene transfer and selection, while similar models which neglect the transfer lead only to monomorphic equilibria.