1. Striking Phenotypic Variation yet Low Genetic Differentiation in Sympatric Lake Trout (Salvelinus namaycush)
- Author
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Paul V. Debes, Robert Spencer Carson, Kia Marin, Dylan J. Fraser, and Andrew Coon
- Subjects
0106 biological sciences ,0301 basic medicine ,Heredity ,Trout ,Speciation ,lcsh:Medicine ,Population genetics ,Marine and Aquatic Sciences ,01 natural sciences ,Effective population size ,Limnology ,lcsh:Science ,Freshwater Ecology ,education.field_of_study ,Multidisciplinary ,Ecology ,Fishes ,Reproductive isolation ,Freshwater Fish ,Sympatric speciation ,Osteichthyes ,Vertebrates ,Research Article ,Freshwater Environments ,Gene Flow ,Evolutionary Processes ,Population ,Biology ,010603 evolutionary biology ,Ecological speciation ,03 medical and health sciences ,Genetics ,Animals ,education ,Salvelinus ,Ecological niche ,Evolutionary Biology ,Population Biology ,lcsh:R ,Ecology and Environmental Sciences ,Organisms ,Aquatic Environments ,Biology and Life Sciences ,Bodies of Water ,biology.organism_classification ,Lakes ,030104 developmental biology ,Genetic Loci ,Earth Sciences ,ta1181 ,lcsh:Q ,Population Genetics - Abstract
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.
- Published
- 2016