Genetics of the Andean bear (Tremarctos ornatus; Ursidae, Carnivora) in Ecuador: when the Andean Cordilleras are not an Obstacle.

One of the top carnivores in the Andean mountains is the Andean bear (Tremarctos ornatus, Ursidae), the only bear in South America. This is a flagship and key umbrella species in Ecuador because its conservation has a positive impact on the conservation of many other species in the Andes. But to preserve, first one must know the genetic characteristics of a species, among other things. For this, we analyzed six mitochondrial genes and seven nuclear DNA microsatellites of 108 Andean bear specimens sampled throughout Ecuador. We adopted three strategies for analyzing the data: by Province, by Region (north vs south), and by Cordillera. Four main results were obtained. First, the mitochondrial genetic diversity levels were elevated, but there were no differences in genetic diversity by Province or by Cordillera. By Regions, southern Ecuador had higher genetic diversity levels than to northern Ecuador. The genetic diversity for the microsatellites was only medium for the Andean bear at this country. Second, there was clear and significant evidence of female population expansions, for the overall sample, by Province, Region, and Cordillera. This population expansion was determined to have occurred in the time interval of 30,000-20,000 years ago (YA), during the last phase of the Pleistocene. We detected a population decrease to have occurred more recently, within the last 5000 years. It continued until about 300-200 YA when a population increase was again detected. Third, there were, practically, no phylogeographic pattern nor genetic differentiation among Andean bear populations in Ecuador by Province or by Cordillera for either mitochondrial or microsatellite markers. There was a little more genetic differentiation between northern and southern areas. Fourth, there was no trace of significant spatial genetic structure for the Andean bear in Ecuador in agreement with the genetic differentiation analyses. This shows that the Andean Cordilleras in this country did not present an obstacle to the dispersion of this species. Therefore, all of the Andean bear specimens in Ecuador should be treated as a unique Management Unit (MU) for conservation purposes, differently to that determined for other countries as Colombia.