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Spatial soft sweeps: Patterns of adaptation in populations with long-range dispersal

Adaptation in extended populations often occurs through multiple independent mutations responding in parallel to a common selection pressure. As the mutations spread concurrently through the population, they leave behind characteristic patterns of polymorphism near selected loci—so-called soft sweep...

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Autores principales: Paulose, Jayson, Hermisson, Joachim, Hallatschek, Oskar
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6386408/
https://www.ncbi.nlm.nih.gov/pubmed/30742615
http://dx.doi.org/10.1371/journal.pgen.1007936
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author Paulose, Jayson
Hermisson, Joachim
Hallatschek, Oskar
author_facet Paulose, Jayson
Hermisson, Joachim
Hallatschek, Oskar
author_sort Paulose, Jayson
collection PubMed
description Adaptation in extended populations often occurs through multiple independent mutations responding in parallel to a common selection pressure. As the mutations spread concurrently through the population, they leave behind characteristic patterns of polymorphism near selected loci—so-called soft sweeps—which remain visible after adaptation is complete. These patterns are well-understood in two limits of the spreading dynamics of beneficial mutations: the panmictic case with complete absence of spatial structure, and spreading via short-ranged or diffusive dispersal events, which tessellates space into distinct compact regions each descended from a unique mutation. However, spreading behaviour in most natural populations is not exclusively panmictic or diffusive, but incorporates both short-range and long-range dispersal events. Here, we characterize the spatial patterns of soft sweeps driven by dispersal events whose jump distances are broadly distributed, using lattice-based simulations and scaling arguments. We find that mutant clones adopt a distinctive structure consisting of compact cores surrounded by fragmented “haloes” which mingle with haloes from other clones. As long-range dispersal becomes more prominent, the progression from diffusive to panmictic behaviour is marked by two transitions separating regimes with differing relative sizes of halo to core. We analyze the implications of the core-halo structure for the statistics of soft sweep detection in small genomic samples from the population, and find opposing effects of long-range dispersal on the expected diversity in global samples compared to local samples from geographic subregions of the range. We also discuss consequences of the standing genetic variation induced by the soft sweep on future adaptation and mixing.
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spelling pubmed-63864082019-03-08 Spatial soft sweeps: Patterns of adaptation in populations with long-range dispersal Paulose, Jayson Hermisson, Joachim Hallatschek, Oskar PLoS Genet Research Article Adaptation in extended populations often occurs through multiple independent mutations responding in parallel to a common selection pressure. As the mutations spread concurrently through the population, they leave behind characteristic patterns of polymorphism near selected loci—so-called soft sweeps—which remain visible after adaptation is complete. These patterns are well-understood in two limits of the spreading dynamics of beneficial mutations: the panmictic case with complete absence of spatial structure, and spreading via short-ranged or diffusive dispersal events, which tessellates space into distinct compact regions each descended from a unique mutation. However, spreading behaviour in most natural populations is not exclusively panmictic or diffusive, but incorporates both short-range and long-range dispersal events. Here, we characterize the spatial patterns of soft sweeps driven by dispersal events whose jump distances are broadly distributed, using lattice-based simulations and scaling arguments. We find that mutant clones adopt a distinctive structure consisting of compact cores surrounded by fragmented “haloes” which mingle with haloes from other clones. As long-range dispersal becomes more prominent, the progression from diffusive to panmictic behaviour is marked by two transitions separating regimes with differing relative sizes of halo to core. We analyze the implications of the core-halo structure for the statistics of soft sweep detection in small genomic samples from the population, and find opposing effects of long-range dispersal on the expected diversity in global samples compared to local samples from geographic subregions of the range. We also discuss consequences of the standing genetic variation induced by the soft sweep on future adaptation and mixing. Public Library of Science 2019-02-11 /pmc/articles/PMC6386408/ /pubmed/30742615 http://dx.doi.org/10.1371/journal.pgen.1007936 Text en © 2019 Paulose et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Paulose, Jayson
Hermisson, Joachim
Hallatschek, Oskar
Spatial soft sweeps: Patterns of adaptation in populations with long-range dispersal
title Spatial soft sweeps: Patterns of adaptation in populations with long-range dispersal
title_full Spatial soft sweeps: Patterns of adaptation in populations with long-range dispersal
title_fullStr Spatial soft sweeps: Patterns of adaptation in populations with long-range dispersal
title_full_unstemmed Spatial soft sweeps: Patterns of adaptation in populations with long-range dispersal
title_short Spatial soft sweeps: Patterns of adaptation in populations with long-range dispersal
title_sort spatial soft sweeps: patterns of adaptation in populations with long-range dispersal
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6386408/
https://www.ncbi.nlm.nih.gov/pubmed/30742615
http://dx.doi.org/10.1371/journal.pgen.1007936
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