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Fitness maps to a large-effect locus in introduced stickleback populations Schluter, Dolph; Marchinko, Kerry; Arnegard, Matt; Zhang, Haili; Brady, Shannon; Jones, Felicity; Bell, Michael; Kingsley, David
Description
<b>Abstract</b><br/>
Mutations of small effect underlie most adaptation to new environments, but beneficial variants with large fitness effects are expected to contribute under certain conditions. Genes and genomic regions having large effects on phenotypic differences between populations are known from numerous taxa, but fitness effect sizes have rarely been estimated. We mapped fitness over a generation in an F2 intercross between a marine and a lake stickleback population introduced to a freshwater pond. A QTL map of the number of surviving offspring per F2 female detected a single, large-effect locus near <i>Ectodysplasin</i> (<i>Eda</i>), a gene having an ancient freshwater allele causing reduced bony armor and other changes. F2 females homozygous for the freshwater allele had twice the number of surviving offspring as homozygotes for the marine allele, producing a large selection coefficient, <i>s</i> = 0.50 ± 0.09 SE. Correspondingly, the frequency of the freshwater allele increased from 0.50 in F2 mothers to 0.58 in surviving offspring. We compare these results to observed allele frequency changes at the <i>Eda</i> gene in an Alaskan lake population colonized by marine stickleback in the 1980’s. The frequency of the freshwater <i>Eda</i> allele rose steadily over multiple generations and reached 95% within 20 years, yielding a similar estimate of selection, <i>s</i> = 0.49 ± 0.05. These findings are consistent with other studies suggesting strong selection on this gene (and/or linked genes) in fresh water. Selection on ancient genetic variants carried by colonizing ancestors is likely to increase the prevalence of large-effect fitness variants in adaptive evolution.</p>
Item Metadata
Title |
Fitness maps to a large-effect locus in introduced stickleback populations
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Creator | |
Date Issued |
2021-05-19
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Description |
<b>Abstract</b><br/>
Mutations of small effect underlie most adaptation to new environments, but beneficial variants with large fitness effects are expected to contribute under certain conditions. Genes and genomic regions having large effects on phenotypic differences between populations are known from numerous taxa, but fitness effect sizes have rarely been estimated. We mapped fitness over a generation in an F2 intercross between a marine and a lake stickleback population introduced to a freshwater pond. A QTL map of the number of surviving offspring per F2 female detected a single, large-effect locus near <i>Ectodysplasin</i> (<i>Eda</i>), a gene having an ancient freshwater allele causing reduced bony armor and other changes. F2 females homozygous for the freshwater allele had twice the number of surviving offspring as homozygotes for the marine allele, producing a large selection coefficient, <i>s</i> = 0.50 ± 0.09 SE. Correspondingly, the frequency of the freshwater allele increased from 0.50 in F2 mothers to 0.58 in surviving offspring. We compare these results to observed allele frequency changes at the <i>Eda</i> gene in an Alaskan lake population colonized by marine stickleback in the 1980’s. The frequency of the freshwater <i>Eda</i> allele rose steadily over multiple generations and reached 95% within 20 years, yielding a similar estimate of selection, <i>s</i> = 0.49 ± 0.05. These findings are consistent with other studies suggesting strong selection on this gene (and/or linked genes) in fresh water. Selection on ancient genetic variants carried by colonizing ancestors is likely to increase the prevalence of large-effect fitness variants in adaptive evolution.</p> |
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Notes |
Dryad version number: 3</p> Version status: submitted</p> Dryad curation status: Published</p> Sharing link: https://datadryad.org/stash/share/9RWipihWXcw2sBQe3wzs5TAq0HwYs9-AFTt6aEpRCek</p> Storage size: 19988714</p> Visibility: public</p> |
Date Available |
2020-12-22
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Provider |
University of British Columbia Library
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License |
This dataset is made available under a Creative Commons CC0 license with the following additional/modified terms and conditions: CC0 Waiver
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DOI |
10.14288/1.0397858
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URI | |
Publisher DOI | |
Grant Funding Agency |
Natural Sciences and Engineering Research Council of Canada; National Institutes of Health; National Science Foundation; Deutsche Forschungsgemeinschaft; Max-Planck-Gesellschaft; Killam Trusts; Howard Hughes Medical Institute
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Rights URI | |
Aggregated Source Repository |
Dataverse
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Licence
This dataset is made available under a Creative Commons CC0 license with the following additional/modified terms and conditions: CC0 Waiver