13 research outputs found
Appendix A. Model results examining relationships between the availability of sea ice habitat and measures of skull width, body length, mass, and condition of polar bears in the southern Beaufort Sea.
Model results examining relationships between the availability of sea ice habitat and measures of skull width, body length, mass, and condition of polar bears in the southern Beaufort Sea
Appendix B. Model results examining trends in measures of skull width, body length, mass, and condition of polar bears in the southern Beaufort Sea between 1983 and 2006.
Model results examining trends in measures of skull width, body length, mass, and condition of polar bears in the southern Beaufort Sea between 1983 and 2006
Electronic Supplementary Material for Regehr et al. 2016 from Conservation status of polar bears (<i>Ursus maritimus</i>) in relation to projected sea-ice declines
Data and analytical methods for generation length, sea ice, and population projection
Appendix A. Definitions of covariates and covariate combinations (groups) used to model survival and recapture probabilities of southern Beaufort Sea polar bears.
Definitions of covariates and covariate combinations (groups) used to model survival and recapture probabilities of southern Beaufort Sea polar bears
Appendix E. Projected trends in the abundance of southern Beaufort Sea polar bears based on estimated survival rates.
Projected trends in the abundance of southern Beaufort Sea polar bears based on estimated survival rates
Appendix B. Southern Beaufort Sea polar bear capture statistics.
Southern Beaufort Sea polar bear capture statistics
Appendix D. An analysis of movement data from southern Beaufort Sea polar bears instrumented with radio-collars.
An analysis of movement data from southern Beaufort Sea polar bears instrumented with radio-collars
Appendix F. The covariate Cap-procliv used to model heterogeneous recapture probabilities of southern Beaufort Sea polar bears.
The covariate Cap-procliv used to model heterogeneous recapture probabilities of southern Beaufort Sea polar bears
Appendix C. Model-averaged estimates of recapture probabilities for southern Beaufort Sea polar bears and total model weights associated with recapture probability covariate structures.
Model-averaged estimates of recapture probabilities for southern Beaufort Sea polar bears and total model weights associated with recapture probability covariate structures
Implications of the Circumpolar Genetic Structure of Polar Bears for Their Conservation in a Rapidly Warming Arctic
<div><p>We provide an expansive analysis of polar bear (<i>Ursus maritimus</i>) circumpolar genetic variation during the last two decades of decline in their sea-ice habitat. We sought to evaluate whether their genetic diversity and structure have changed over this period of habitat decline, how their current genetic patterns compare with past patterns, and how genetic demography changed with ancient fluctuations in climate. Characterizing their circumpolar genetic structure using microsatellite data, we defined four clusters that largely correspond to current ecological and oceanographic factors: Eastern Polar Basin, Western Polar Basin, Canadian Archipelago and Southern Canada. We document evidence for recent (ca. last 1–3 generations) directional gene flow from Southern Canada and the Eastern Polar Basin towards the Canadian Archipelago, an area hypothesized to be a future refugium for polar bears as climate-induced habitat decline continues. Our data provide empirical evidence in support of this hypothesis. The direction of current gene flow differs from earlier patterns of gene flow in the Holocene. From analyses of mitochondrial DNA, the Canadian Archipelago cluster and the Barents Sea subpopulation within the Eastern Polar Basin cluster did not show signals of population expansion, suggesting these areas may have served also as past interglacial refugia. Mismatch analyses of mitochondrial DNA data from polar and the paraphyletic brown bear (<i>U. arctos</i>) uncovered offset signals in timing of population expansion between the two species, that are attributed to differential demographic responses to past climate cycling. Mitogenomic structure of polar bears was shallow and developed recently, in contrast to the multiple clades of brown bears. We found no genetic signatures of recent hybridization between the species in our large, circumpolar sample, suggesting that recently observed hybrids represent localized events. Documenting changes in subpopulation connectivity will allow polar nations to proactively adjust conservation actions to continuing decline in sea-ice habitat.</p></div