Submitted to: Journal of Heredity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/2006
Publication Date: 7/12/2006
Citation: Cronin, M.D., Macneil, M.D., Patton, J.C. 2006. Mitochondrial dna and microsatellite dna variation in domestic reindeer (rangifer tarandus tarandus) and relationships with wild caribou (r. t. granti, r. t. groenlandicus, r. t. caribou). Journal of Heredity 97:525-530. doi:10.1093/jhered/es1012. Interpretive Summary: Domestic reindeer were introduced to western Alaska from Siberia in eastern Russia between 1892 and 1902 to provide native people a means of reliable meat production. There are approximately 20,000 reindeer currently in Alaska. Reindeer in Alaska are thought to have interbred with wild caribou on open ranges raising concerns regarding genetic fitness in wild populations and suitability for domestic production. Alaskan reindeer also provide an interesting opportunity for comparisons of genetic variation and differentiation at two levels: among introduced herds and herds from the geographic region of origin; and between domestic and wild relatives of the same species. Genetic variation of reindeer from Alaska, Siberia Russia, and Scandinavia and microsatellite allele frequencies of reindeer and wild caribou were quantified in this paper. Based on mitochondrial DNA sequences, a single large clade was found to contain all 15 of the reindeer genotypes and three wild barren ground caribou genotypes. Woodland caribou genotype occurs in a separate clade. Based on microsatellite markers in the nuclear DNA, there was a relatively low level of differentiation among Alaskan and Siberian reindeer with a higher level of differentiation between these herds and the Scandinavian herds. Alaskan and Canadian barren ground caribou were genetically distinct from both the reindeer and woodland caribou. Domestication may have resulted in the lower levels of genetic variation observed in reindeer compared to wild caribou. However, reindeer herds in Alaska and Siberia appear to have considerable levels of genetic variation. These findings ally concerns about gene flow between domesticated and wild populations of reindeer and caribou in Alaska and provide evidence for the genetic sustainability of both.
Technical Abstract: Alaskan reindeer (Rangifer tarandus tarandus) are descended from 1280 animals introduced from Siberia, Russia 110 years ago. Genetic variation at 18 microsatellite DNA loci and the cytochrome-b gene of mitochondrial DNA (mtDNA) was quantified in reindeer from seven herds in Alaska, three herds in Siberia Russia, and three herds in Scandinavia. There is considerable microsatellite DNA variation in reindeer, with 16 of 18 loci polymorphic, 2-15 alleles per locus, and observed heterozygosity of 0.303-0.472 among herds. Mean sequence divergence among 15 mtDNA genotypes in reindeer was 0.007 substitutions per nucleotide site. The herds in Alaska and Siberia have comparable levels of mtDNA and microsatellite DNA genetic variation. Microsatellite allele frequencies and mtDNA genotype distributions are similar among Alaskan and Russian reindeer herds and differentiated between these herds and Scandinavian reindeer. Genetic variation was also compared between reindeer and wild barren ground caribou (R. t. granti, R. t. groenlandicus) and woodland caribou (R. t. caribou) of North America. Microsatellite variation is higher in wild caribou than domestic reindeer. Phylogenetic relationships of mtDNA genotypes were polyphyletic among reindeer and caribou. However, microsatellite allele frequencies and mtDNA genotypes are different in reindeer and caribou. Extant patterns of genetic variation reflect recent and past distribution of populations and levels of gene flow.