The gut microbiota plays a critical role in host health, yet remains poorly studied in wild species. Polar bears (Ursus maritimus), key indicators of Arctic ecosystem health and environmental change, are currently affected by rapid shifts in habitat that may alter gut homeostasis. Declining sea ice has led to a divide in the southern Beaufort Sea polar bear subpopulation such that an increasing proportion of individuals now inhabit onshore coastal regions during the open-water period (‘onshore bears’) while others continue to exhibit their typical behaviour of remaining on the ice (‘offshore bears’). We propose that bears that have altered their habitat selection in response to climate change will exhibit a distinct gut microbiota diversity and composition, which may ultimately have important consequences for their health. Here, we perform the first assessment of abundance and diversity in the faecal microbiota of wild polar bears using 16S rRNA Illumina technology. We find that bacterial diversity is significantly higher in onshore bears compared to offshore bears. The most enriched OTU abundance in onshore bears belonged to the phylum Proteobacteria, while the most depleted OTU abundance within onshore bears was seen in the phylum Firmicutes. We conclude that climate-driven changes in polar bear land use are associated with distinct microbial communities. In doing so, we present the first case of global change mediated alterations in the gut microbiota of a free-roaming wild animal.
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We would like to thank G. Durner, A. Pagano, K. Simac, L. Peacock and T. Donnelly for capturing and sampling of polar bears, which was funded by the USGS. We are grateful to F. Albonico and the staff of the Conservation Genetics Unit at the Fondazione Edmund Mach, Italy for their training and guidance. Laboratory facilities and partial funding for the metataxonomic analyses were provided by the Fondazione E. Mach. This paper was reviewed and approved by the USGS under their Fundamental Science Practices policy (http://www.usgs.gov/fsp). Any use of trade, product or firm names is for descriptive purposes only and does not imply endorsement by the US Government. S.E.W. is supported by a NERC GW4 + Doctoral Training Partnership studentship from the Natural Environment Research Council [NE/L002434/1].
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Watson, S.E., Hauffe, H.C., Bull, M.J. et al. Global change-driven use of onshore habitat impacts polar bear faecal microbiota. ISME J 13, 2916–2926 (2019). https://doi.org/10.1038/s41396-019-0480-2
FEMS Microbiology Ecology (2020)