Nucleotide  variation in the mitochondrial genome provides evidence for dual routes of  postglacial recolonization and genetic recombination in the northeastern brook  trout (Salvelinus fontinalis).
Levels  and patterns of mitochondrial DNA (mtDNA) variation were examined to  investigate the population structure and possible routes of postglacial  recolonization of the world's northernmost native populations of brook trout (Salvelinus  fontinalis), which are found in Labrador, Canada. We analyzed the sequence  diversity of a 1960-bp portion of the mitochondrial genome (NADH dehydrogenase  1 gene and part of cytochrome oxidase 1) of 126 fish from 32 lakes distributed  throughout seven regions of northeastern Canada. These populations were found  to have low levels of mtDNA diversity, a characteristic trait of populations at  northern extremes, with significant structuring at the level of the watershed.  Upon comparison of northeastern brook trout sequences to the publicly available  brook trout whole mitochondrial genome (GenBank AF154850), we infer that the  GenBank sequence is from a fish whose mtDNA has recombined with that of Arctic  charr (S. alpinus). The haplotype distribution provides evidence of two  different postglacial founding groups contributing to present-day brook trout  populations in the northernmost part of their range; the evolution of the  majority of the haplotypes coincides with the timing of glacier retreat from  Labrador. Our results exemplify the strong influence that historical processes  such as glaciations have had on shaping the current genetic structure of  northern species such as the brook trout.
Department of Biology, Memorial University of Newfoundland and Labrador, St. John's, Newfoundland and Labrador, Canada. brettneylp@mun.ca
B L
BL
Pilgrim
R C
RC
Perry
J L
JL
Barron
H D
HD
Marshall
D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D002170:Canada; D017753:Ecosystem; D003576:Electron Transport Complex IV / Q000235:genetics; D005618:Fresh Water; D014644:Genetic Variation; D005828:Genetics, Population; D054629:Genome, Mitochondrial / Q000235:genetics*; D005843:Geography; D006239:Haplotypes / Q000235:genetics; D046448:Ice Cover; D008969:Molecular Sequence Data; D009245:NADH Dehydrogenase / Q000235:genetics; D009711:Nucleotides / Q000235:genetics*; D016366:Open Reading Frames / Q000235:genetics; D010802:Phylogeny; D011157:Population Dynamics; D011995:Recombination, Genetic; D018401:Sample Size; D016415:Sequence Alignment; D014337:Trout / Q000235:genetics*
D009711:Nucleotides; D009245:NADH Dehydrogenase; D003576:Electron Transport Complex IV