ABSTRACT Animals in the Arctic have low pathogen diversity but with rapid climate warming, this i... more ABSTRACT Animals in the Arctic have low pathogen diversity but with rapid climate warming, this is expected to change. One insidious consequence of climate change is exposure of Arctic species to new pathogens derived from more southern species expanding their range northward. To assess potential vulnerability of polar bears to disease exposure, we examined genetic variation in major histocompatibility complex (MHC) loci (part of immune system) in Canadian polar bears and found low genetic diversity, consistent with long-standing exposure to low pathogen/ parasite loads. All polar bears surveyed showed maximum linkage disequilibrium between DRB/DQB loci and 12% of individuals had a duplicated DQB gene haplotype. These results may reflect balancing selection at these loci, a response to an earlier immune-challenge and/or be artifacts of polar bear-brown bear divergence. Consistent with the latter, we found one DQA allele in polar bears that was also a brown bear DQA allele. The reported low MHC diversity and high linkage disequilibrium may have serious implications for polar bear resistance to new pathogens, which would be maladaptive to species in an environment undergoing rapid climate change, such as the Arctic.
CITES regulates international trade with the goal of preventing over-exploitation, thus the survi... more CITES regulates international trade with the goal of preventing over-exploitation, thus the survival of species are not jeopardized from trade practices; however it has been used recently in nontrade conservation measures. As an example, the US proposed to up-list polar bears under CITES Appendix I, despite that the species did not conform to the biological criteria. Polar bears were listed as ‘threatened’ under US ESA in 2008, in response to loss of sea-ice and warming temperatures. In Nunavut, where most of Canada’s polar bears are harvested, the resulting trade ban did not decrease total harvest after the ESA listing but reduced US hunter participation and the proportion of quotas taken by sport hunters from specific populations. Consequently, the import ban impacted livelihoods of Arctic indigenous communities with negative conservation — reduced tolerance for dangerous fauna and affected local participation in shared management initiatives. The polar bear may be the exemplar of an emerging problem: the use of trade bans in place of action for non-trade threats, e.g., climate change. Conservation prospects for this species and other climate-sensitive wildlife will likely diminish if the increasing use of trade bans to combat non-trade issues cause stakeholders to lose faith in participatory management.
ABSTRACT Animals in the Arctic have low pathogen diversity but with rapid climate warming, this i... more ABSTRACT Animals in the Arctic have low pathogen diversity but with rapid climate warming, this is expected to change. One insidious consequence of climate change is exposure of Arctic species to new pathogens derived from more southern species expanding their range northward. To assess potential vulnerability of polar bears to disease exposure, we examined genetic variation in major histocompatibility complex (MHC) loci (part of immune system) in Canadian polar bears and found low genetic diversity, consistent with long-standing exposure to low pathogen/ parasite loads. All polar bears surveyed showed maximum linkage disequilibrium between DRB/DQB loci and 12% of individuals had a duplicated DQB gene haplotype. These results may reflect balancing selection at these loci, a response to an earlier immune-challenge and/or be artifacts of polar bear-brown bear divergence. Consistent with the latter, we found one DQA allele in polar bears that was also a brown bear DQA allele. The reported low MHC diversity and high linkage disequilibrium may have serious implications for polar bear resistance to new pathogens, which would be maladaptive to species in an environment undergoing rapid climate change, such as the Arctic.
CITES regulates international trade with the goal of preventing over-exploitation, thus the survi... more CITES regulates international trade with the goal of preventing over-exploitation, thus the survival of species are not jeopardized from trade practices; however it has been used recently in nontrade conservation measures. As an example, the US proposed to up-list polar bears under CITES Appendix I, despite that the species did not conform to the biological criteria. Polar bears were listed as ‘threatened’ under US ESA in 2008, in response to loss of sea-ice and warming temperatures. In Nunavut, where most of Canada’s polar bears are harvested, the resulting trade ban did not decrease total harvest after the ESA listing but reduced US hunter participation and the proportion of quotas taken by sport hunters from specific populations. Consequently, the import ban impacted livelihoods of Arctic indigenous communities with negative conservation — reduced tolerance for dangerous fauna and affected local participation in shared management initiatives. The polar bear may be the exemplar of an emerging problem: the use of trade bans in place of action for non-trade threats, e.g., climate change. Conservation prospects for this species and other climate-sensitive wildlife will likely diminish if the increasing use of trade bans to combat non-trade issues cause stakeholders to lose faith in participatory management.
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Papers by Diana Weber