Investigating the ancestry of putative hybrids: are Arctic fox and red fox hybridizing?
Global climate change induces species range shifts and population expansion to higher latitudes in response to rising temperatures. One consequence of climate-induced range shifts is an increased sympatry between related but previously isolated species, potentially resulting in interspecific interactions and hybridization. The Arctic is more rapidly affected by climate warming than any region on Earth and resident species may be prone to interspecific hybridization due to the immigration of new colonizing species. The red fox Vulpes vulpes expanded its range into the Arctic during the twentieth century and is now in sympatry with the native Arctic fox Vulpes lagopus in many places. In this context, an Arctic-like fox displaying an unusual reddish winter coat was observed in 2013 in Nunavut, Canada, a phenotype unknown by Inuit people to date. In this study, we assessed the biological origin of this specimen with a multigenic approach using markers located on mitochondrial DNA, sex (X and Y) chromosomes, and autosomes (microsatellites and the melanocortin 1 receptor (MC1R) gene; a gene involved in the color polymorphism in canids). Our comparative analyses with genetic material from Arctic and red foxes displaying “classic” phenotypes (N = 14 and 16, respectively) suggested a pure Arctic fox origin of the specimen. Specifically, this fox yielded mtDNA, X-linked, Y-linked, and MC1R alleles specific to Arctic fox. Bayesian genetic assignment based on 16 microsatellite loci assigned it to Arctic fox with high confidence (q = 99.7%). Thus, a recent hybrid origin for this specimen is excluded. This alternative winter coat color polymorphism in Arctic fox requires further analyses to determine its underlying genetic mechanism.
KeywordsVulpes lagopus Vulpes vulpes Climate warming Species expansion mtDNA Sexual chromosome MC1R
We thank the Government of Nunavut for its logistical support. Field work was supported by (alphabetical order) Canada Foundation for Innovation, Canada Research Chairs, Environment Canada, Government of Nunavut, Indian and Northern Affairs Canada, Igloolik Hunters and Trappers Organization, Natural Sciences and Engineering Research Council of Canada, Polar Continental Shelf Project (PCSP), and Université de Moncton. Funding for laboratory work was provided by a LabEx OSUG@2020 grant to GY. Pictures of Arctic foxes (Fig. 1) were kindly provided by Emmanuelle Pouivé (a) and Philippe Garcia (b–d; http://www.explographe.com). We also thank Nathalie Tissot and Nadine Curt-Grand-Gaudin for lab assistance. Comments by Thomas Broquet and Christophe Dufresnes improved the clarity of this work.
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