Variation in skull morphology of brown bears (Ursus arctos) from Caucasus

Abstract

There has been debate over the taxonomic status of brown bears (Ursus arctos) from Caucasus, for almost 150 years. At the end of the last century, different forms of Caucasian bears living in the same area were described. Subsequently, researchers recognized from one to four subspecies of brown bears from Caucasus. We collected measurements on skulls of bears, conducted electrophoretic analysis of variation in blood proteins, and conducted 7 years of field surveys in Caucasus. Multivariate analysis of cranial variables revealed the existence of three groups, or ecomorphs, apparent in both male and female Caucasian bears, which supported previous work that showed diversity in this group. The existence of these groups was not due to age, geographic variation, or temporal changes in populations. Different distributions between morphs was documented in both crania and field observations. The most likely explanation of these differences was a Mendelian inheritance of the whole complex of differences. Differences in territorial behavior during the mating season among males of various ecomorphs suggest selective breeding. Despite the discovery of three polymorphic proteins, no firm conclusions could be made because the diversity in these proteins did not relate to results from the cranial analysis.