Widespread, long‐term admixture between grey wolves and domestic dogs across Eurasia and its implications for the conservation status of hybrids

Abstract

Hybridisation between a domesticated species and its wild ancestor is an important conservation problem, especially if it results in the introgression of domestic gene variants into wild species. Nevertheless, the legal status of hybrids remains unregulated, partially because of the limited understanding of the hybridisation process and its consequences. The occurrence of hybridisation between grey wolves and domestic dogs is well documented from different parts of the wolf geographic range, but little is known about the frequency of hybridisation events, their causes and the genetic impact on wolf populations. We analysed 61K SNPs spanning the canid genome in wolves from across Eurasia and North America and compared that data to similar data from dogs to identify signatures of admixture. The haplotype block analysis, which included 38 autosomes and the X chromosome, indicated the presence of individuals of mixed wolf–dog ancestry in most Eurasian wolf populations, but less admixture was present in North American populations. We found evidence for male‐biased introgression of dog alleles into wolf populations, but also identified a first‐generation hybrid resulting from mating between a female dog and a male wolf. We found small blocks of dog ancestry in the genomes of 62% Eurasian wolves studied and melanistic individuals with no signs of recent admixed ancestry, but with a dog‐derived allele at a locus linked to melanism. Consequently, these results suggest that hybridisation has been occurring in different parts of Eurasia on multiple timescales and is not solely a recent phenomenon. Nevertheless, wolf populations have maintained genetic differentiation from dogs, suggesting that hybridisation at a low frequency does not diminish distinctiveness of the wolf gene pool. However, increased hybridisation frequency may be detrimental for wolf populations, stressing the need for genetic monitoring to assess the frequency and distribution of individuals resulting from recent admixture.

True Colors: commercially-acquired morphological genotypes reveal hidden allele variation among dog breeds, informing both trait ancestry and breed potential

“…The derived alleles at ASIP , MC1R , CBD103 have previously been detected at low frequency in various populations of coyotes and wolves, most of which have been postulated to occur due to introgression with domestic dogs (51–54). Such introgression between grey wolves and domestic dogs has been documented to occur at low levels across Eurasia, but detailed studies of domestic dog introgression with wolves and other species (coyotes, dingoes) in other geographic areas are sparse (55,56). Our grey wolf (n = 12) population was largely collected on the East coast of North America, and theoretically has more opportunities for introgression with domestic dogs due to higher human (and pet dog) population density compared to their Western North American counterparts.…”

On the path to extinction: Inbreeding and admixture in a declining grey wolf population

“…Instead, our results suggest that the presence of small dog chromosome blocks may be compatible with ancient interbreeding events (Thompson, ) and imply that genes of dog origin might be pervasive within the genomes of Iberian wolves. Previous studies have suggested that some dog genes may have been introgressed and been positively selected for and spread in certain North American and Eurasian wolf populations (Anderson et al., ; Pilot et al., ). However, our study shows that the introgression of a very large number of dog chromosomal fragments may not be as rare as initially thought.…”

Increased genetic marker density reveals high levels of admixture between red deer and introduced Japanese sika in Kintyre, Scotland

“…Empirically, use of high-density markers has indeed led to an increase in detection of backcrossed individuals. For example in Italy where wolves and dogs have hybridized, 1 – 5% of wolves were found to be hybrid individuals when 16 – 18 microsatellite markers were used (Randi 2008), whereas 62% of sampled individuals were determined to be hybrid when 170 000 SNP markers were used (Pilot et al 2018). Although the individuals sampled were not the same, and the study goals differed, it is telling that there is such a discrepancy in the estimated proportion of hybrid individuals when a high density marker panel was used.…”