@article{PavlovaNabeNielsenDietzetal.2014,
  author    = {Pavlova, Viola and Nabe-Nielsen, Jacob and Dietz, Rune and Svenning, Jens-Christian and Vorkamp, Katrin and Riget, Frank Farso and Sonne, Christian and Letcher, Robert J. and Grimm, Volker},
  title     = {Field metabolic rate and PCB adipose tissue deposition efficiency in East Greenland polar bears derived from contaminant monitoring data},
  series = {PLoS one},
  volume    = {9},
  journal   = {PLoS one},
  number    = {8},
  publisher = {PLoS},
  address   = {San Fransisco},
  issn      = {1932-6203},
  doi       = {10.1371/journal.pone.0104037},
  pages     = {10},
  year      = {2014},
  abstract  = {Climate change will increasingly affect the natural habitat and diet of polar bears (Ursus maritimus). Understanding the energetic needs of polar bears is therefore important. We developed a theoretical method for estimating polar bear food consumption based on using the highly recalcitrant polychlorinated biphenyl (PCB) congener, 2,2',4,4',55-hexaCB (CB153) in bear adipose tissue as an indicator of food intake. By comparing the CB153 tissue concentrations in wild polar bears with estimates from a purposely designed individual-based model, we identified the possible combinations of field metabolic rates (FMR) and CB153 deposition efficiencies in East Greenland polar bears. Our simulations indicate that if 30\% of the CB153 consumed by polar bear individuals were deposited into their adipose tissue, the corresponding FMR would be only two times the basal metabolic rate. In contrast, if the modelled CB153 deposition efficiency were 10\%, adult polar bears would require six times more energy than that needed to cover basal metabolism. This is considerably higher than what has been assumed for polar bears in previous studies though it is similar to FMRs found in other marine mammals. An implication of this result is that even relatively small reductions in future feeding opportunities could impact the survival of East Greenland polar bears.},
  language  = {en}
}
@article{CoramanDietzHempeletal.2019,
  author    = {Coraman, Emrah and Dietz, Christian and Hempel, Elisabeth and Ghazaryan, Astghik and Levin, Eran and Presetnik, Primoz and Zagmajster, Maja and Mayer, Frieder},
  title     = {Reticulate evolutionary history of a Western Palaearctic Bat Complex explained by multiple mtDNA introgressions in secondary contacts},
  series = {Journal of biogeography},
  volume    = {46},
  journal   = {Journal of biogeography},
  number    = {2},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0305-0270},
  doi       = {10.1111/jbi.13509},
  pages     = {343 -- 354},
  year      = {2019},
  abstract  = {Aim There is an increasing evidence showing that species within various taxonomic groups have reticulate evolutionary histories with several cases of introgression events. Investigating the phylogeography of species complexes can provide insight into these introgressions, and when and where these hybridizations occurred. In this study, we investigate the biogeography of a widely distributed Western Palaearctic bat species complex, namely Myotis nattereri sensu lato. This complex exhibits high genetic diversity and in its western distribution range is composed of deeply diverged genetical lineages. However, little is known about the genetic structure of the eastern populations. We also infer the conservation and taxonomical implications of the identified genetic divergences. Taxon Myotis nattereri sensu lato including M. schaubi. Location Western Palaearctic. Methods We analysed 161 specimens collected from 67 locations and sequenced one mitochondrial and four nuclear DNA markers, and combined these with the available GenBank sequences. We used haplotype networks, PCA, t-SNE and Bayesian clustering algorithms to investigate the population structure and Bayesian trees to infer the phylogenetic relationship of the lineages. Results We identified deeply divergent genetical lineages. In some cases, nuclear and mitochondrial markers were discordant, which we interpret are caused by hybridization between lineages. We identified three such introgression events. These introgressions occurred when spatially separated lineages came into contact after range expansions. Based on the genetic distinction of the identified lineages, we suggest a revision in the taxonomy of this species group with two possible new species: M. hoveli and M. tschuliensis. Main conclusions Our findings suggest that the M. nattereri complex has a reticulate evolutionary history with multiple cases of hybridizations between some of the identified lineages.},
  language  = {en}
}
@article{PavlovaGrimmDietzetal.2016,
  author    = {Pavlova, Viola and Grimm, Volker and Dietz, Rune and Sonne, Christian and Vorkamp, Katrin and Riget, Frank F. and Letcher, Robert J. and Gustavson, Kim and Desforges, Jean-Pierre and Nabe-Nielsen, Jacob},
  title     = {Modeling Population-Level Consequences of Polychlorinated Biphenyl Exposure in East Greenland Polar Bears},
  series = {Archives of environmental contamination and toxicology},
  volume    = {70},
  journal   = {Archives of environmental contamination and toxicology},
  publisher = {Springer},
  address   = {New York},
  issn      = {0090-4341},
  doi       = {10.1007/s00244-015-0203-2},
  pages     = {143 -- 154},
  year      = {2016},
  abstract  = {Polychlorinated biphenyls (PCBs) can cause endocrine disruption, cancer, immunosuppression, or reproductive failure in animals. We used an individual-based model to explore whether and how PCB-associated reproductive failure could affect the dynamics of a hypothetical polar bear (Ursus maritimus) population exposed to PCBs to the same degree as the East Greenland subpopulation. Dose-response data from experimental studies on a surrogate species, the mink (Mustela vision), were used in the absence of similar data for polar bears. Two alternative types of reproductive failure in relation to maternal sum-PCB concentrations were considered: increased abortion rate and increased cub mortality. We found that the quantitative impact of PCB-induced reproductive failure on population growth rate depended largely on the actual type of reproductive failure involved. Critical potencies of the dose-response relationship for decreasing the population growth rate were established for both modeled types of reproductive failure. Comparing the model predictions of the age-dependent trend of sum-PCBs concentrations in females with actual field measurements from East Greenland indicated that it was unlikely that PCB exposure caused a high incidence of abortions in the subpopulation. However, on the basis of this analysis, it could not be excluded that PCB exposure contributes to higher cub mortality. Our results highlight the necessity for further research on the possible influence of PCBs on polar bear reproduction regarding their physiological pathway. This includes determining the exact cause of reproductive failure, i.e., in utero exposure versus lactational exposure of offspring; the timing of offspring death; and establishing the most relevant reference metrics for the dose-response relationship.},
  language  = {en}
}