Resumo

JUAREZ-CASILLAS, Luis Antonio; VARAS, Cora  e  CERVANTES, Fernando A.. Phylogenetic analysis of the evolutionary lineage of Mexican black bears (Ursus americanus). Therya [online]. 2013, vol.4, n.3, pp.467-484. ISSN 2007-3364.  https://doi.org/10.12933/therya-13-155.

The black bear (Ursus americanus) has been present in North America at least during 3 million years ago. Climatic changes from last glaciation drove black bears to seek refuge in two regions of North America, one in the Pacific side and other in the Atlantic side, shaping the present genetic structure of this ursid. Literature reports attempting to confirm these hypotheses have not included samples from Mexico. Therefore, this research examined the genetic variation of black bear populations from all over its range, to find out if Mexican populations of the black bear belong to the phylogenetic branch of the Pacific clade or to that of the Atlantic clade. DNA sequences of the mitochondrial control region were obtained from scat samples collected in northern Mexico and from data downloaded from GenBank. Phylogenetic analyses confirmed the existence of one clade west of the Rocky Mountains and a second clade to the east of the same mountains, including the mountains themselves. In addition, our data also showed that Mexican populations of the black bear are nested into the phylogenetic branch of the Atlantic side. This research thus supports that genetic structure of Mexican black bears may have been influenced by climatic changes of the last glaciation period. Further research is needed to better understand genetic distances between eastern and western populations of Mexican black bears. Conservation efforts to protect black bears in Mexico must consider their origin and phylogenetic relationships.

Palavras-chave : Carinivore; Conservation; Genetic diversity; North America; Pleistocene refugia; Ursidae.