Sex Kontaktanzeigen Pirna
The Hadamar Diskrete Treffen Pirna Andere Mädchen: Erotische Abenteuer Ternitz, Sextreffen heute Dülmen, Schnelle Sexkontakte Sandefjord
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Professor in Molecular Systematics , University of Oslo. Supervising Master and Dr. Molecular systematics, Molecular evolution, Genome evolution, Phylogeny, Population genetics, ancient DNA analyses, taxonomy and systematics of parasitic flatworms class Monogenea , marine mammals.
The polar bear Ursus maritimus has become a symbol of the threat to biodiversity from climate change. Understanding polar bear evolutionary history may provide insights into apex carnivore responses and prospects during periods of extreme environmental perturbations.
In recent years, genomic studies have examined bear speciation and population history, including evidence for ancient admixture between polar bears and brown bears Ursus arctos. A slightly higher genetic diversity in the ancient polar bear suggests a severe genetic erosion over a prolonged bottleneck in modern polar bears. Statistical fitting of data to alternative admixture graph scenarios favors at least one ancient introgression event from brown bears into the ancestor of polar bears, possibly dating back over , y.
Gene flow was likely bidirectional, but allelic transfer from brown into polar bear is the strongest detected signal, which contrasts with other published work. These findings may have implications for our understanding of climate change impacts: Polar bears, a specialist Arctic lineage, may not only have undergone severe genetic bottlenecks but also been the recipient of generalist, boreal genetic variants from brown bears during critical phases of Northern Hemisphere glacial oscillations.
The intense, temporally extensive hunting pressure may have left the population vulnerable to other perturbations, such as environmental change. However, the lack of genomic baseline data renders it difficult to evaluate the impacts of various potential stressors on this stock. All individuals were unrelated and void of significant signs of inbreeding, with similar observed and expected homo- and heterozygosity levels. Despite the small population size, mean autosome-wide heterozygosity was 0.
