Investigating genomic and phenotypic parallelism between piscivorous and planktivorous Lake Trout (Salvelinus namaycush) ecotypes by means of RADseq and morphometrics analyses (original) (raw)
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Genetic and phenotypic variation along an ecological gradient in lake trout Salvelinus namaycush
BMC evolutionary biology, 2016
Adaptive radiation involving a colonizing phenotype that rapidly evolves into at least one other ecological variant, or ecotype, has been observed in a variety of freshwater fishes in post-glacial environments. However, few studies consider how phenotypic traits vary with regard to neutral genetic partitioning along ecological gradients. Here, we present the first detailed investigation of lake trout Salvelinus namaycush that considers variation as a cline rather than discriminatory among ecotypes. Genetic and phenotypic traits organized along common ecological gradients of water depth and geographic distance provide important insights into diversification processes in a lake with high levels of human disturbance from over-fishing. Four putative lake trout ecotypes could not be distinguished using population genetic methods, despite morphological differences. Neutral genetic partitioning in lake trout was stronger along a gradient of water depth, than by locality or ecotype. Contemp...
Environmental Biology of Fishes, 2012
Humans have played a significant role in reducing levels of genetic diversity and differentiation of many teleost fishes, leading to homogenization across biological entities. We compare patterns of historical and contemporary genetic structure for three sympatric Great Lake's lake trout (Salvelinus namaycush) morphs (lean, siscowet, and humper) that differ in patterns of habitat occupancy, susceptibility to overfishing and predation by invasive sea lamprey (Petromyzon marinus). Differential susceptibilities to overfishing and ...
Ecological opportunities present during colonization of novel environments can drive divergent selection on traits, resulting in specialization of morphs to enhance efficient use of resources and, potentially, intraspecific divergence and ecological speciation. Thus, in an ecologically polymorphic species, differences in resource specialization should be found among morphs, and homogeneity in resource use expected within a morph. Using the piscivorous lake trout morph, one of four morphs in Great Bear Lake, we investigate whether specialization of trophic resources among individuals occurs within this single morph, which could indicate a potential for continued divergence. Four distinct dietary patterns of resource use within the piscivorous lake trout morph were detected from analyses of fatty acid composition. In general, feeding habits of different groups within the piscivorous morph were not associated with detectable morphological or genetic differentiation, suggesting that beh...
Polymorphism in northern fishes is common, but the extent to which polymorphism occurs in Lake Trout Salvelinus namaycush, a species generally associated with low intraspecific variation, is not well known. This study examined the polymorphism of Lake Trout inhabiting the shallow-water zones (≤30 m) of Great Bear Lake, Northwest Territories. We combined an analysis of classical morphometric and traditional linear measures with shape analysis (geometric morphometrics) to quantify morphological differences in body shape, head shape, and fin and body length measurements among 558 adult and 55 juvenile shallow-water Lake Trout from Great Bear Lake. A UPGMA cluster analysis on adult Lake Trout distinguished three different morphs that coexist in the shallow-water habitat. The most important differences among adult morphotypes were associated with head and fin measurements, whereas body shape variation was less distinct. A fourth, albeit rarer, morph was supported by a multivariate ANOVA that indicated significant differences in head and fin characteristics among the four groups. The divergent morphologies among the shallow-water Lake Trout of Great Bear Lake are consistent with traits generally associated with feeding and swimming. In contrast to adult trout, no consistent patterns were found for juveniles, suggesting that phenotypic differences develop at a later stage. This unusual level of endemic diversity in the shallow-water habitat expands our knowledge of Lake Trout diversity beyond the predominant focus on shallow- versus deepwater forms.