Post by grrraaahhh on Sept 9, 2010 18:31:07 GMT -9
Some small European populations of the brown bear (Ursus arctos) are threatened by the risk of extinction in the near future. The reinforcement of these populations with bears from other regions might provide a solution to their future survival. However, before any population transfer, the different conservation units must be identified. The phylogeographic approach has been advocated for this purpose. The different European populations were assayed for mitochondrial (mt) DNA polymorphism. A remarkable degree of concordance was found between the geographic distribution and the mtDNA haplotypes. Two clearly distinct lineages differing by more than 7 % in mtDNA control region sequences were found and, furthermore, the western lineage appears to be organized into two clades which correspond to two different ancestral refugia. The potential conservation units can be deduced from these results, and a management policy can consequently be inferred. This study clearly demonstrates the relevance of the molecular phylogeographic approach to the identification of conservation units.
Mitochondrial DNA polymorphism, phylogeography, and conservation genetics of the brown bear Ursus arctos in Europe
Post by grrraaahhh on Oct 17, 2010 21:30:32 GMT -9
Bear Hunting Altered Genetics More Than Ice Age Isolation
Twenty thousand years ago Europe was covered by ice down to Germany, and the climate in the rest of Europe was such that several species were confined to the southern regions, like the Iberian Peninsula and Italy. These regions were refuges, areas where species could survive during cold periods and then re-colonize central and northern Europe when it got warmer.
But the brown bear was not limited to these regions -- it could roam freely across major parts of southern and central Europe. The current study analyzed mitochondria from bear remains. Some of the fossils are 20,000 years old. The analysis shows that the genetic pattern in these ancient brown bears differed from that of bears living today.
“Previously today’s genetic structure was interpreted as showing that the brown bear was isolated in southern Europe, just like many other species. But our study shows that this was not the case,” says Love Dalén, one of the Swedes participating in the study.
The new findings show instead that the brown bear survived in central Europe, even during the coldest period of the Ice Age. The scientists now believe that the genetic pattern found in today’s brown bears is the result of historical hunting and of human activities in the brown bear’s natural environment. A few thousand years ago, there were brown bears all over Europe, while today there are just a few remaining populations in Spain, Italy, the Balkans, and Scandinavia.
ORPHANS In Estonia, several bear cubs are orphaned each year. In 1998–1989, 12 orphaned cubs were found. Abandonment or death of the mother are the 2 main reasons leading to such cases. In a majority of cases, females with cubs have been disturbed during denning by forest logging or by hunting near the bear den. Hunting for wild boar [Sus scrofa] with dogs has been the most frequent type of hunt- ing that disturbs bears. When disturbed, females often abandon their young (H. Valdmann, U. Saarma, and A. Karis, unpublished data). The killing of female brown bears with cubs is less frequent than disturbance (one case in 1999). Although female brown bears are not legally protected from hunting while accompanied by dependent young, most hunters avoid shooting them. When orphans are found, people either take cubs into captivity or leave them. In recent years, general attitudes have favored tak- ing cubs into captivity, raising them to the age they can survive on their own, and releasing them to the same area of the forest they were originally found. A special “home” exists for orphan bears where they can be taken after they have been found to be abandoned. With the aid of Pazhetnov’s family from Russia, who have developed a methodology for rising lone cubs (Pazhetnov et al. 1999), 9 orphan bears have been raised and released during 1998– 99. Raising young bears in captivity is admirable and hard work, but at the moment we are not confident that this is the best way to help orphaned cubs. Habituation to people can become a problem for orphans. Pazhetnov’s method is applicable in areas where human settlements are far from the ultimate release site. Even in the most remote areas of Estonia, human density is higher than required by the above method. Young bears can travel relatively long dis- tances. We know of one instance in which a young bear traveled 32 kilometers from the point of liberation within a few days. In 1999, 3 young bears often visited gardens in a village near the place they were released back into the wild. According to observations by local people, these bears were impudent but not aggressive. As an alternative to raising bears in captivity, abandoned young bears can be left in the forest and supplied by food up to a certain age. Studies in Scandinavia have shown that brown bear cubs can survive well on their own from as early as 6 months of age (Swenson et al. 1998b). Whether the latter strategy is suitable and superior to the present one in Estonia remains to be investigated..."
BIOGEOGRAPHY, DEMOGRAPHY AND MANAGEMENT OF URSUS ARCTOS IN THE WESTERN CARPATHIANS
Abstract: During the 1930s the brown bear (Ursus arctos) population in the western Carpathians was endangered and numbered <60 animals. Following total protection during 1932-60 and harvest management since 1960, this population gradually increased in both number and range. Now, about 600 animals inhabit approximately 12,500 km2 in Slovakia. Within this area 8,000 km2 is optimum habitat and supports >0.6 bears/10 km2. In addition 2,500 km2 supports <0.6 bears/km2 with the remaining 2,000 km2 having only transient bear occurrences. Harvest has been allowed since 1960, and population dynamics are significantly influenced by harvest regulations. From 1960 through 1980, 291 bears were harvested. Of these 230 (79%) were males and 61 (21%) were females. This excessive harvesting of males changed the sex and age structure of the population, allowed excessive population growth, and reduced natural selection pressure. During 1981-91 the growth coefficient of the population averaged 11.2%. Some improvement was noted after the establishment of a selective harvest regime. Of 176 bears harvested during 1981-91 weighing <100 kg, 36% were males and 64% females. On the basis of these data, yearly quotas were designed to encourage the harvest of subadult animals weighing <100 kg. Although this harvest design was not strictly observed, from 1981 through 1991, 441 bears were harvested, of which 281 (66%) were males and 160 (34%) were females.