A1 Refereed original research article in a scientific journal
Striking Phenotypic Variation yet Low Genetic Differentiation in Sympatric Lake Trout (Salvelinus namaycush)
Authors: Kia Marin, Andrew Coon, Robert Carson, Paul V. Debes, Dylan J. Fraser
Publisher: Public Library of Science
Publication year: 2016
Journal: PLoS ONE
Journal name in source: PloS one
Journal acronym: PLoS One
Volume: 11
Issue: 9
Number of pages: 23
ISSN: 1932-6203
eISSN: 1932-6203
DOI: https://doi.org/10.1371/journal.pone.0162325
Web address : http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0162325
Self-archived copy’s web address: https://research.utu.fi/converis/portal/Publication/29766637
The study of population differentiation in the context of ecological speciation is commonly assessed using populations with obvious discreteness. Fewer studies have examined diversifying populations with occasional adaptive variation and minor reproductive isolation, so factors impeding or facilitating the progress of early stage differentiation are less understood. We detected non-random genetic structuring in lake trout (Salvelinus namaycush) inhabiting a large, pristine, postglacial lake (Mistassini Lake, Canada), with up to five discernible genetic clusters having distinctions in body shape, size, colouration and head shape. However, genetic differentiation was low (FST = 0.017) and genetic clustering was largely incongruent between several population- and individual-based clustering approaches. Genotype- and phenotype-environment associations with spatial habitat, depth and fish community structure (competitors and prey) were either inconsistent or weak. Striking morphological variation was often more continuous within than among defined genetic clusters. Low genetic differentiation was a consequence of relatively high contemporary gene flow despite large effective population sizes, not migration-drift disequilibrium. Our results suggest a highly plastic propensity for occupying multiple habitat niches in lake trout and a low cost of morphological plasticity, which may constrain the speed and extent of adaptive divergence. We discuss how factors relating to niche conservatism in this species may also influence how plasticity affects adaptive divergence, even where ample ecological opportunity apparently exists.
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