Reindeer
Genetic, molecular, and archaeological evidence

Meanwhile, genetic data continued to accumulate, revealing sufficiently deep divisions to easily separate Rangifer back into six previously named species and to resurrect several previously named subspecies. Molecular data showed that the Greenland caribou (R. t. groenlandicus) and the Svalbard reindeer (R. t. platyrhynchus), although not closely related to each other, were the most genetically divergent among Rangifer clades; that modern (see Evolution above) Eurasian tundra reindeer (R. t. tarandus and R. t. sibiricus) and North American barren-ground caribou (R. t. arcticus), although sharing ancestry, were separable at the subspecies level; that Finnish forest reindeer (R. t. fennicus) clustered well apart from both wild and domestic tundra reindeer and that boreal woodland caribou (R. t. caribou) were separable from all others. Meanwhile, archaeological evidence was accumulating that Eurasian forest reindeer descended from an extinct forest-adapted reindeer and not from tundra reindeer (see Evolution above); since they do not share a direct common ancestor, they cannot be Biological specificity#conspecific|conspecific. Similarly, woodland caribou diverged from the ancestors of Arctic caribou before modern barren-ground caribou had evolved, and were more likely related to extinct North American forest reindeer (see Evolution above). Lacking a direct shared ancestor, barren-ground and woodland caribou cannot be conspecific.

Molecular data also revealed that the four western Canadian montane ecotypes are not woodland caribou: they share a common ancestor with modern barren-ground caribou / tundra reindeer, but distantly, having diverged > 60,000 years ago — before the modern ecotypes had evolved their cold- and darkness-adapted physiologies and mass-migration and aggregation behaviors (see Evolution above). Before Banfield (1961), taxonomists using cranial, dental and skeletal measurements had unequivocally allied these western montane ecotypes with barren-ground caribou, naming them (as in Osgood 1909 Murie, 1935 and Anderson 1946, among others) R. t. stonei, R. t. montanus, R. t. fortidens and R. t. osborni, respectively, and this phylogeny was confirmed by genetic analysis.
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