Genetic and Morphological Divergence in Three Strains of Brook Trout Salvelinus fontinalis Commonly Stocked in Lake Superior

Abstract

Fitness related traits often show spatial variation across populations of widely distributed species. Comparisons of genetic variation among populations in putatively neutral DNA markers and in phenotypic traits susceptible to selection (QST FST analysis) can be used to determine to what degree differentiation among populations can be attributed to selection or genetic drift. Traditionally, QST FST analyses require a large number of populations to achieve sufficient statistical power; however, new methods have been developed that allow QST FST comparisons to be conducted on as few as two populations if their pedigrees are informative. This study compared genetic and morphological divergence in three strains of brook trout Salvelinus fontinalis that were historically or currently used for stocking in the Lake Superior Basin. Herein we examined if morphological divergence among populations showed temporal variation, and if divergence could be attributed to selection or was indistinguishable from genetic drift. Multivariate QST FST analysis showed evidence for divergent selection between populations. Univariate analyses suggests that the pattern observed in the multivariate analyses was largely driven by divergent selection for length and weight, and moreover by divergence between the Assinica strain and each of the Iron River and Siskiwit strains rather than divergent selection between each population pair. While it could not be determined if divergence was due to natural selection or inadvertent artificial selection in hatcheries, selected differences were consistent with patterns of domestication commonly found in salmonids.

Reliance on lakes by salmon, trout and charr (Oncorhynchus,SalmoandSalvelinus): An evaluation of spawning habitats, rearing strategies and trophic polymorphisms

“…The smolting process of adfluvial salmonids is parallel to that of adfluvial fish; most notably, they lose their parr marks and acquire silvery coloration suited to the open‐water environment (e.g. S. salar —Staurnes, Lysfjord, & Berg, ; S. fontinalis —McKinney, Varian, Scardina, & Nichols, ; Figure ). In partially migrant non‐anadromous populations, where individuals may follow either a fluvial or adfluvial life history, females exhibit a bias for migration and males for residency (e.g.…”

Using Linkage Maps as a Tool To Determine Patterns of Chromosome Synteny in the Genus Salvelinus

“…The two strains are genetically distinct from each other ( F st = 0.13; Cooper et al 2010 ; Stott et al 2010 ). The Siskiwit River population has been used for heritability studies of phenotypes connected with migration ( Varian and Nichols 2010 ; McKinney et al 2014 ). The Tobin Harbor population has been used to study the ecological differences between coaster and stream living (fluvial) Trout ( Huckins and Baker 2008 ).…”

“…Although research on Brook Trout has been less intensive than on other salmonids, recent studies have described variation in several evolutionary traits of interest such as morphology, size, age of sexual maturation, and water temperature tolerance ( e.g. , Varian and Nichols 2010 ; McKinney et al 2014 ; McDermid et al 2012 ; Serfas et al 2012 ; Kazyak et al 2013 ). Many of these traits have been shown to have a genetic basis in other salmonids, including development rate in Rainbow Trout ( Sundin et al 2005 ; Nichols et al 2007 ; Miller et al 2012 ), age at maturation in Atlantic Salmon ( Barson et al 2015 ), migration run timing in Chinook Salmon and Rainbow Trout ( Hess et al 2016 ), and temperature tolerance in Chinook Salmon ( Everett and Seeb 2014 ) and Rainbow Trout ( Narum et al 2013 ).…”

Common gardens in teosintes reveal the establishment of a syndrome of adaptation to altitude

“…S is the posterior probability that divergence among populations was not driven by drift only. Following [60], we used here a conservative credibility value of S > 0.95 to declare divergent selection.…”