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Environmental heterogeneity can tip the population genetics of range expansions

The population genetics of most range expansions is thought to be shaped by the competition between Darwinian selection and random genetic drift at the range margins. Here, we show that the evolutionary dynamics during range expansions is highly sensitive to additional fluctuations induced by enviro...

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Detalles Bibliográficos
Autores principales: Gralka, Matti, Hallatschek, Oskar
Formato: Online Artículo Texto
Lenguaje:English
Publicado: eLife Sciences Publications, Ltd 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6513619/
https://www.ncbi.nlm.nih.gov/pubmed/30977724
http://dx.doi.org/10.7554/eLife.44359
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author Gralka, Matti
Hallatschek, Oskar
author_facet Gralka, Matti
Hallatschek, Oskar
author_sort Gralka, Matti
collection PubMed
description The population genetics of most range expansions is thought to be shaped by the competition between Darwinian selection and random genetic drift at the range margins. Here, we show that the evolutionary dynamics during range expansions is highly sensitive to additional fluctuations induced by environmental heterogeneities. Tracking mutant clones with a tunable fitness effect in bacterial colonies grown on randomly patterned surfaces we found that environmental heterogeneity can dramatically reduce the efficacy of selection. Time-lapse microscopy and computer simulations suggest that this effect arises generically from a local 'pinning’ of the expansion front, whereby stretches of the front are slowed down on a length scale that depends on the structure of the environmental heterogeneity. This pinning focuses the range expansion into a small number of 'lucky’ individuals with access to expansion paths, altering the neutral evolutionary dynamics and increasing the importance of chance relative to selection.
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spelling pubmed-65136192019-05-16 Environmental heterogeneity can tip the population genetics of range expansions Gralka, Matti Hallatschek, Oskar eLife Evolutionary Biology The population genetics of most range expansions is thought to be shaped by the competition between Darwinian selection and random genetic drift at the range margins. Here, we show that the evolutionary dynamics during range expansions is highly sensitive to additional fluctuations induced by environmental heterogeneities. Tracking mutant clones with a tunable fitness effect in bacterial colonies grown on randomly patterned surfaces we found that environmental heterogeneity can dramatically reduce the efficacy of selection. Time-lapse microscopy and computer simulations suggest that this effect arises generically from a local 'pinning’ of the expansion front, whereby stretches of the front are slowed down on a length scale that depends on the structure of the environmental heterogeneity. This pinning focuses the range expansion into a small number of 'lucky’ individuals with access to expansion paths, altering the neutral evolutionary dynamics and increasing the importance of chance relative to selection. eLife Sciences Publications, Ltd 2019-04-12 /pmc/articles/PMC6513619/ /pubmed/30977724 http://dx.doi.org/10.7554/eLife.44359 Text en © 2019, Gralka and Hallatschek http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/This article is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use and redistribution provided that the original author and source are credited.
spellingShingle Evolutionary Biology
Gralka, Matti
Hallatschek, Oskar
Environmental heterogeneity can tip the population genetics of range expansions
title Environmental heterogeneity can tip the population genetics of range expansions
title_full Environmental heterogeneity can tip the population genetics of range expansions
title_fullStr Environmental heterogeneity can tip the population genetics of range expansions
title_full_unstemmed Environmental heterogeneity can tip the population genetics of range expansions
title_short Environmental heterogeneity can tip the population genetics of range expansions
title_sort environmental heterogeneity can tip the population genetics of range expansions
topic Evolutionary Biology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6513619/
https://www.ncbi.nlm.nih.gov/pubmed/30977724
http://dx.doi.org/10.7554/eLife.44359
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