Assessing Genetic Diversity of Lake Trout (Salvelinus namaycush) Populations in Saskatchewan
The genetic diversity of lake trout from 19 lakes in Saskatchewan was examined using partial regions of the ND2 and ND5 mtDNA genes. A total of 607 tissue samples were analyzed using PCR-based single stranded conformation polymorphism (SSCP) and DNA sequencing. Although the ND5 gene fragment had minimal intraspecific variation, eleven sequence types were detected in the ND2 gene. Each sequence type differed in relative frequency between and among the lake trout populations sampled.
One particular southern lake trout population, Crean Lake, had markedly different genetic composition in comparison to other lakes in the region. In the 1950s and 1960s, Crean Lake was stocked with lake trout from neighbouring Wassegam Lake in an attempt to increase population numbers. The sequence types of Crean Lake trout and their relative frequencies were dramatically different to those in Wassegam Lake. This suggests that the stocked fish may have been unsuccessful in their establishment/reproduction within Crean Lake. Lake trout from this lake also contained the highest frequency (44%) of rare ND2 sequence type B. Sequence type B was only detected in one other lake (La Ronge), at a very low frequency.
The mutational changes in the eleven ND2 mitochondrial DNA sequence types represented three different amino acid sequence types. Substitutions of Threonine and Isoleucine occurred, resulting in two polar amino acids with much different hydropathy indexes. This may affect the tertiary structure of the protein, possibly indicating functional differences. Functionally different proteins may be exhibiting characteristics that allow lake trout to flourish in their environment.
The fragments of both the ND2 and ND5 genes proved to be valuable for phylogenetic analyses within the Salmonidae. The genetic markers established in the present study provide the basis for future work on population genetics of lake trout. It would be advantageous to broaden the area of study in order to compare the genetic diversity found within the study area to other regions of Canada. This would determine whether the genetic diversity detected in this study is significantly greater than in other populations at a national scale. Management strategies should ultimately attempt to conserve the genetic diversity found within the lake trout populations of north central Saskatchewan.
Advisor:Chilton, Neil; Chivers, Doug; Fitzsimmons, Michael; Evans, Marlene
School:University of Saskatchewan
School Location:Canada - Saskatchewan
Source Type:Master's Thesis
Keywords:lake trout salvelinus namaycush genetic diversity mitochondrial dna nad5 nad2 sscp
Date of Publication:05/20/2008