Patterns of MHC-DRB1 polymorphism in a post-glacial island canid, the Newfoundland red fox (Vulpes vulpes deletrix), suggest balancing selection at species and population timescales

Abstract

As the only native insular Newfoundland canid between the extinction of the wolf in the 1930s and the recent arrival of coyotes, the red fox (Vulpes vulpes deletrix Bangs 1898) poses interesting questions about genetic distinctiveness and the post-glacial colonization history of the island’s depauperate mammalian fauna. Here, we characterized genetic variability at the major histocompatibility complex (MHC) class II DR β1 domain (DRB1) locus in 28 red foxes from six sampling localities island-wide and compared it with mitochondrial control region (CR) diversity and DRB1 diversity in other canids. Our goals were to describe novel DRB1 alleles in a new canid population and to make inferences about the role of selection in maintaining their diversity. As in numerous studies of vertebrates, we found an order-of-magnitude higher nucleotide diversity at the DRB1 locus compared with the CR and significantly positive nonsynonymous-to-synonymous substitution ratios, indicative of selection in the distant past. Although the evidence is weaker, the Ewens-Watterson test of neutrality and the geographical distribution of variation compared with the CR suggest a role for selection over the evolutionary timescale of populations. We report the first genetic data from the DRB1 locus in the red fox and establish baseline information regarding immunogenetic variation in this island canid population which should inform continued investigations of population demography, adaptive genetic diversity, and wildlife disease in red foxes and related species.

Sarcoptic mange severity is associated with reduced genomic variation and evidence of selection in Yellowstone National Park wolves (Canis lupus)

“…Through these analyses, we found evidence of selection acting on mange‐associated loci following the 2007 invasion of S. scabiei mites in YNP. Although numerous studies have catalogued immunogenetics in canids (Aguilar et al., 2004; Arbanasić et al., 2013; Galaverni, Caniglia, Fabbri, Lapalombella, & Randi, 2013; Hedrick, Lee, & Garrigan, 2002; Hedrick, Lee, & Parker, 2000; Kennedy et al., 2011; Marshall, Langille, Hann, & Whitney, 2016), this study was among the first to explore genome‐wide variation within the context of disease severity in a wild canid population. This allowed us to test whether host genomic variation was predictive of disease severity, as suggested by the monoculture effect observed in agricultural settings (Ekroth et al., 2019).…”

Spatiotemporal spread of sarcoptic mange in the red fox (Vulpes vulpes) in Switzerland over more than 60 years: lessons learnt from comparative analysis of multiple surveillance tools

“…Demographic bottlenecks and population separations may lead to a decrease of genetic diversity [77]. This may limit the adaptive potential of populations to pathogens [78, 79] and, in turn, influence disease dynamics and increase vulnerability to diseases [80, 81]. The fox population collapse (already denominated as “rabies pit” [56]) in the Plateau and the Jura may have impaired, on the one hand, the transmission of S. scabiei due to the reduced density and therefore contacts among foxes and, on the other hand, removed diseased and also resistant individuals, disrupting the long-term host-parasite adaptation and generating a susceptible “naïve-like” population.…”

Positive selection on the MHC class II DLA-DQA1 gene in golden jackals (Canis aureus) from their recent expansion range in Europe and its effect on their body mass index

“…High polymorphism at MHC loci, especially in the peptide binding regions, is maintained by balancing selection, as a response to resistance to diverse arrays of pathogens (e.g., [ 6 , 8 ]). Variability of class II genes has been characterized for several canid species, such as dogs, Canis lupus f. familiaris (e.g., [ 9 , 10 ]), wolves , Canis lupus, (e.g., [ 11 – 16 ]), African wild dogs, Lycaon pictus , (e.g., [ 17 , 18 ]), coyotes, Canis latrans , [ 11 , 19 ], arctic foxes, Vulpes lagopus , [ 20 ], and red foxes, Vulpes vulpes , [ 21 ]. However, so far only one study has examined MHC variability in golden jackals from a restricted geographical range in the Balkans [ 22 ].…”