For instance, decreases in genetic variation with increasing distance from glacial refugia have been observed in several species of fishes Stamford and Taylor ; Harris and Taylor a. One way to increase our understanding of the relative roles of historical and contemporary influences on genetic diversity and population structure is to use comparative methods.
Elk Lake fish were more fusiform, elongate, and streamlined with a narrower caudal peduncle compared to hatchery lean strains and wild lean forms from the Isle Royale region of Lake Superior. Re-use of this article is permitted in accordance with the Creative Commons Deed, Attribution 2.
The identification of new gamete sources may be beneficial to lake trout reintroduction efforts, particularly in situations where native stocks have been completely extirpated such as in Lake Michigan. For example, contemporary connectivity facilitating gene flow among populations will reduce genetic differentiation Dionne et al.
Arctic systems provide unique opportunities for investigating the roles of historical and contemporary processes in shaping the genetic structure in populations of freshwater fishes.
This permits the study of processes such as contemporary dispersal, gene flow, and source-sink population dynamics Dias ; Palstra et al. Gene flow, glaciations, history, panmictic, Salvelinus Introduction The extent of genetic structure among, and variation within, populations of north temperate faunas is expected to be markedly different from that exhibited by populations from more southerly latitudes, which were exempt from the direct impacts of Pleistocene glaciations Hewitt Evolutionary processes such as founder events associated with post-glacial dispersal and historical bottlenecks as a result of glacial cycles are offered as potential explanations for some of these observations Bernatchez et al.
Additional recent studies of lake trout in GBL have examined morphological variation and trophic resource polymorphism in this species Blackie et al. Virtually all Arctic populations of fishes were impacted by Pleistocene glaciation events through the displacement of populations during glacial maxima and then the recolonization of contemporary ranges when the ice-sheets receded Lindsey and McPhail ; Pielou Differences in patterns between geography and genetic variation are also expected.
Disentangling the relative influences of historical and contemporary factors, such as historical gene flow versus contemporary dispersal, on population genetic structure can present formidable challenges Sobel et al. The biology and evolutionary ecology of lake trout is relatively well studied in other large lakes, for example, the heavily anthropogenically impacted Laurentian Great Lakes Moore and Bronte ; Guinand et al.
Lake trout from Elk Lake, Michigan, are genetically distinct from domestic hatchery strains and historical forms of lake trout from Lake Michigan. In the case of Great Lakes lake trout, diversity has been severely compromised. Arctic populations of fishes are relatively less studied than those at more southerly latitudes and therefore the evolutionary ecology of many Arctic fish populations remains unresolved e.
Previous article in issue. For example, populations with contemporary ranges spanning areas formerly glaciated during the Pleistocene Epoch are expected to show reduced levels of genetic variation and historical effective population size NEas well as reduced levels of DNA sequence and phylogenetic divergence compared with those from unglaciated areas Hewitt ; Bernatchez and Wilson ; Hewitt Importantly, Elk Lake fish were genetically distinct from Marquette strain lake trout which were previously stocked into Elk Lake.
Some groups of fishes dispersed remarkable distances across numerous watersheds post-glacially to occupy their current range Bernatchez and Dodson ; Rempel and Smith ; Wilson and Hebert ; Witt et al.
Elk Lake lake trout is as genetically diverse as other strains used in Great Lakes reintroduction efforts and likely represent a viable gamete source representing genetic diversity lost from Lake Michigan.
Furthermore, contemporary landscape and environmental features of aquatic ecosystems e. The lake is oligotrophic and is characterized by very low species diversity Johnson b. Alternatively, recent reductions in population size, resulting from anthropogenic disturbances Stamford and Taylor ; Hanfling and Weetmanfor example, can reduce genetic variation and promote genetic divergence through genetic drift, especially in small populations Consuegra et al.
Fishes in particular, given their reliance on aquatic habitats for survival, were clearly impacted by glacial events e. Although current patterns of phylogeography, population structure, and genetic variation among and within populations of northern fishes can be largely explained by historical events, contemporary factors also contribute to these patterns.
Furthermore, many Arctic systems are characterized by complex and dynamic watersheds harboring a multitude of populations, many of which exist in a meta-population framework.
While all individuals exhibited characteristics of lean form lake trout, the body shape of lake trout from Elk Lake, stocked lean fish from Lake Michigan and Lake Superior wild lean strains from near Isle Royale differed.An analysis of the observed heterozygosity of Lake Trout populations from three lakes: Devil, Eagle, and Loughborough, inferred from microsatellite.
Microsatellite and mtDNA analysis of lake trout, Salvelinus namaycush, from Great Bear Lake, Lake trout (Salvelinus Although each sample contained loci with higher than expected heterozygosity given the observed number of alleles, no significant deviations from equilibrium were detected.
Evidence of a remnant self-sustaining strain of lake trout in the Lake Michigan basin For morphometric analysis, adult stocked lake trout were collected from Lake Michigan during summer and fall Deviations of observed and expected heterozygosity reflected in relatively high and significant positive F is were documented in lake.
Genetic and phenotypic evidence for splake presence in brook trout and lake trout ). However, brook trout have also been observed spawning on shoal areas of lakes that consist of gravel and smaller rocks at less (heterozygosity, number of alleles per locus) were obtained using the program FSTAT (version ; Goudet, ).
An analysis of the observed heterozygosity of Lake Trout populations from three lakes: Devil, Eagle, and Loughborough, inferred from microsatellite genotypes. Genetic Differentiation among Lake Trout Strains the average observed heterozygosity wasand the proportion of polymorphic loci was Hierarchical analysis indicated that the.Download