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United States Department of Agriculture

Agricultural Research Service

Title: Variation in Mitochondrial DNA and Microsatellite DNA in Caribou (Rangifer Tarandus) in North America

Authors
item Cronin, Matthew - UNIV OF ALASKA
item Macneil, Michael
item Patton, John - TEXAS A&M UNIV

Submitted to: Journal of Mammalogy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 23, 2004
Publication Date: January 25, 2005
Citation: Cronin, M.W., Macneil, M.D., Patton, J.C. 2005. Variation in mitochondrial dna and microsatellite dna in caribou (rangifer tarandus) in north america. Journal of Mammalogy 86:495-505.

Interpretive Summary: There are four subspecies of caribou commonly recognized in North America. These subspecies have been designated based on variation in morphology, habitat use, and behavior. However, it is generally agreed that subspecies designations should be based on phylogenetic relatedness, which is not clear for the North American subspecies of caribou. We quantify the genetic relationships among three caribou subspecies (R. t. granti, R. t. groenlandicus, and R. t. caribou) in North America with 18 microsatellite loci and mitochondrial DNA (mtDNA) sequences. Phylogenetic analysis of 1194 nucleotides of mtDNA sequence resulted in two primary groups of genotypes. Microsatellite allele frequencies also indicate genetic differentiation of the subspecies. Within subspecies, there is relatively low differentiation of microsatellite allele frequencies among herds of R. t. granti and R. t. groenlandicus. Four Alaskan R. t. granti herds with contiguous ranges (Central Arctic, Western Arctic, Teshukpuk Lake, Porcupine River) have similar microsatellite allele frequencies, and share mtDNA genotypes. Three Canadian R. t. groenlandicus herds in separate geographic areas (Victoria Island; Baffin Island; Hope Lake, Northwest Territories) are more differentiated from each other than are the Alaska herds for microsatellite allele frequencies, although they share mtDNA genotypes. The frequencies of microsatellite alleles and mtDNA genotypes of R. t. caribou in four geographically separate areas (Québec, Labrador, Alberta, Newfoundland) in Canada are highly differentiated from each other. Use of phylogenetic criteria to distinguish subspecies will allow criteria for management of species to be established objectively.

Technical Abstract: Genetic variation of caribou at 18 microsatellite loci and the cytochrome-b gene of mitochondrial DNA (mtDNA) was quantified in eleven herds. The herds included three North American subspecies: Alaska barren ground caribou (R. t. granti), Canadian barren ground caribou (R. t. groenlandicus), and woodland caribou (R. t. caribou). Phylogenetic analysis of 1194 nucleotides of cytochrome-b mtDNA sequences resulted in two primary groups of genotypes. One group of 52 genotypes occurs in R. t. granti and R. t. groenlandicus and in one herd of R. t. caribou. A smaller group of 7 genotypes occurs only in R. t. caribou. MtDNA sequence divergence is approximately 1% between these groups and 0.3% to 0.6% within these groups. Each subspecies does not have strictly monophyletic mtDNA, but frequencies of mtDNA genotypes are different in each subspecies. Microsatellite allele frequencies also indicate genetic differentiation of woodland (R. t. caribou) and barren ground (R. t. granti and R. t. groenlandicus) subspecies. Within subspecies, there is relatively low differentiation of microsatellite allele frequencies among herds of R. t. granti and R. t. groenlandicus. Four Alaskan R. t. granti herds with contiguous ranges (Central Arctic, Western Arctic, Teshukpuk Lake, Porcupine River) have similar microsatellite allele frequencies, and share mtDNA genotypes. Three Canadian R. t. groenlandicus herds in separate geographic areas (Victoria Island; Baffin Island; Hope Lake, Northwest Territories) are more differentiated from each other than are the Alaska herds for microsatellite allele frequencies, although they share mtDNA genotypes. The frequencies of microsatellite alleles and mtDNA genotypes of R. t. caribou in four geographically separate areas (Québec, Labrador, Alberta, Newfoundland) in Canada are highly differentiated from each other. The extent of differentiation of mtDNA genotype frequencies and microsatellite allele frequencies within and among each subspecies reflects past and present gene flow among herds.

Last Modified: 8/19/2014
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