Mitochondrial phylogeography, subspecific taxonomy, and conservation genetics of sandhill cranes (Grus canadensis; Aves: Gruidae)
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- Phymer, J.M., Fain, M.G., Austin, J.E. et al. Conservation Genetics (2001) 2: 203. doi:10.1023/A:1012203532300
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Six subspecies of sandhill cranes (Gruscanadensis) have been denoted based onperceived morphological and/or breedinglocality differences among them. Threesubspecies are migratory, breeding from thehigh arctic in North America and Siberia(lesser sandhill, G. c. canadensis),south through central Canada (Canadiansandhill, G. c. rowani) and into thenorthern United States (greater sandhill, G. c. tabida). A review of sandhill cranetaxonomy indicates that the size variation, onthe basis of which these subspecies were named,may be clinal and not diagnostic. The otherthree subspecies, all listed as endangered orthreatened, are non-migratory, resident inFlorida (G. c. pratensis), Mississippi(G. c. pulla), and Cuba (G. c.nesiotes). We used analysis of mitochondrialDNA control region (CR) sequences to determinewhether haplotypes representing currentsubspecies show any genetic cohesion or aremore consistent with a pattern of clinalvariation in morphology. CR sequences indicatethat only two highly divergent (5.3%) lineagesof sandhill cranes occur in North America: onelineage composed only of arctic-nesting G.c. canadensis, the other of the remainingNorth American subspecies (we lack data on theCuban population). The deep split betweenlineages is consistent with an estimatedisolation of approximately 1.5 Mya(mid-Pleistocene), while the distribution ofmutational changes within lineages isconsistent with an hypothesis of rapid,post-Pleistocene population expansions. Noother phylogeographic structuring is concordantwith subspecific boundaries, however, analysisof molecular variance indicates that there issignificant population genetic differentiationamong all subspecies except G. c. tabidaand G. c. rowani, which areindistinguishable. We suggest thatrecognition of the recently named G. c.rowani be abandoned.