Environment heterogeneity creates fast amplifiers of natural selection in graph-structured populations

Fuente: arXiv
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Autores principales: Fruet, Cecilia, Alexandre, Arthur, Abbara, Alia, Loverdo, Claude, Bitbol, Anne-Florence
Formato: Preprint
Publicado: 2025
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author Fruet, Cecilia
Alexandre, Arthur
Abbara, Alia
Loverdo, Claude
Bitbol, Anne-Florence
author_facet Fruet, Cecilia
Alexandre, Arthur
Abbara, Alia
Loverdo, Claude
Bitbol, Anne-Florence
contents Complex spatial structure, with partially isolated subpopulations, and environment heterogeneity, such as gradients in nutrients, oxygen, and drugs, both shape the evolution of natural populations. We investigate the impact of environment heterogeneity on mutant fixation in spatially structured populations with demes on the nodes of a graph. When migrations between demes are frequent, we find that environment heterogeneity can amplify natural selection and simultaneously accelerate mutant fixation and extinction, thereby fostering the quick fixation of beneficial mutants. We demonstrate this effect in the star graph, and more strongly in the line graph. We show that amplification requires mutants to have a stronger fitness advantage in demes with stronger migration outflow, and that this condition allows amplification in more general graphs. As a baseline, we consider circulation graphs, where migration inflow and outflow are equal in each deme. In this case, environment heterogeneity has no impact to first order, but increases the fixation probability of beneficial mutants to second order. Finally, when migrations between demes are rare, we show that environment heterogeneity can also foster amplification of selection, by allowing demes with sufficient mutant advantage to become refugia for mutants.
format Preprint
id arxiv_https___arxiv_org_abs_2507_23769
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Environment heterogeneity creates fast amplifiers of natural selection in graph-structured populations
Fruet, Cecilia
Alexandre, Arthur
Abbara, Alia
Loverdo, Claude
Bitbol, Anne-Florence
Populations and Evolution
Complex spatial structure, with partially isolated subpopulations, and environment heterogeneity, such as gradients in nutrients, oxygen, and drugs, both shape the evolution of natural populations. We investigate the impact of environment heterogeneity on mutant fixation in spatially structured populations with demes on the nodes of a graph. When migrations between demes are frequent, we find that environment heterogeneity can amplify natural selection and simultaneously accelerate mutant fixation and extinction, thereby fostering the quick fixation of beneficial mutants. We demonstrate this effect in the star graph, and more strongly in the line graph. We show that amplification requires mutants to have a stronger fitness advantage in demes with stronger migration outflow, and that this condition allows amplification in more general graphs. As a baseline, we consider circulation graphs, where migration inflow and outflow are equal in each deme. In this case, environment heterogeneity has no impact to first order, but increases the fixation probability of beneficial mutants to second order. Finally, when migrations between demes are rare, we show that environment heterogeneity can also foster amplification of selection, by allowing demes with sufficient mutant advantage to become refugia for mutants.
title Environment heterogeneity creates fast amplifiers of natural selection in graph-structured populations
topic Populations and Evolution
url https://arxiv.org/abs/2507.23769