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Genome-phenotype-environment associations identify signatures of selection in a panmictic population of threespine stickleback
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  • Kasha Strickland,
  • Katja Räsänen,
  • Bjarni Kristjánsson,
  • Joseph Phillips,
  • Arni Einarsson,
  • Ragna Snorradóttir,
  • Mireia Bartrons,
  • Zophonías Oddur Jónsson
Kasha Strickland
The University of Edinburgh

Corresponding Author:[email protected]

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Katja Räsänen
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Bjarni Kristjánsson
Hólar University College
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Joseph Phillips
Creighton University
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Arni Einarsson
Myvatn research Station
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Ragna Snorradóttir
Holar University College
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Mireia Bartrons
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Zophonías Oddur Jónsson
University of Iceland
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Adaptive genetic divergence occurs when selection imposed by the environment causes the genomic component of the phenotype to differentiate. However, genomic signatures of natural selection are usually identified without information on which trait is responding to selection by which selective agent(s). Here, we integrate whole-genome-sequencing with phenomics and measures of putative selective agents to assess the extent of adaptive divergence in threespine stickleback occupying the highly heterogeneous lake Mývatn, NE Iceland. We find negligible genome wide divergence, yet multiple traits (body size, gill raker structure and defense traits) were divergent along known ecological gradients (temperature, predatory bird densities and water depth). SNP based heritability of all measured traits was high (h2 = 0.42 – 0.65), indicating adaptive potential for all traits. Whilst environment-association analyses identified thousands of loci putatively involved in selection, related to genes linked to neuron development and protein phosphorylation, only allelic variation linked to pelvic spine length was concurrently linked to environmental variation (water depth) - supporting the conclusion that divergence in pelvic spine length occurred in face of gene flow. Our results suggest that whilst there is substantial genetic variation in the traits measured, phenotypic divergence of Mývatn stickleback is mostly weakly associated with environmental gradients, potentially as a result of substantial gene flow. Our study illustrates the value of integrative studies that combine genomic assays of multivariate trait variation with landscape genomics.
14 Jul 2022Submitted to Molecular Ecology
15 Jul 2022Submission Checks Completed
15 Jul 2022Assigned to Editor
03 Aug 2022Reviewer(s) Assigned
30 Aug 2022Review(s) Completed, Editorial Evaluation Pending
06 Oct 2022Editorial Decision: Revise Minor
01 Dec 20221st Revision Received
01 Dec 2022Review(s) Completed, Editorial Evaluation Pending
13 Dec 2022Editorial Decision: Accept