The genetic legacy of extirpation and re-colonization in Vancouver Island wolves

Abstract

Hybridization between wild and domestic species is of conservation concern because it can result in the loss of adaptations and/or disappearance of a distinct taxon. Wolves from Vancouver Island, British Columbia (Canada), have been subject to several eradication campaigns during the twentieth century and were considered virtually extirpated between 1950 and 1970. In this study, we use control region mitochondrial DNA sequences and 13 autosomal microsatellite loci to characterize Vancouver Island wolves as well as dogs from British Columbia. We observe a turnover in the haplotypes of wolves sampled before and after the 1950-1970 period, when there was no permanent wolf population on the island, supporting the probable local extinction of wolves on Vancouver Island during this time, followed by re-colonization of the island by wolves from mainland British Columbia. In addition, we report the presence of a domestic dog mtDNA haplotype in three individuals eliminated in 1986 that were morphologically identified as wolves. Here we show that Vancouver Island wolves were also identified as wolves based on autosomal microsatellite data. We attribute the hybridization event to the episodically small size of this population during the recolonization event. Our results demonstrate that at least one female hybrid offspring, resulting from a cross of a male wolf and a female dog or a female hybrid pet with dog mtDNA, successfully introgressed into the wolf population. No dog mtDNA has been previously reported in a population of wild wolves. Genetic data show that Vancouver Island wolves are distinct from dogs and thus should be recognized as a population of wild wolves. We suggest that the introgression took place due to the Allee effect, specifically a lack of mates when population size was low. Our findings exemplify how small populations are at risk of hybridization.

Wolf-dog hybridization in Croatia

“…These findings could suggest that (1) YH08 is a rare haplotype also present in domestic dogs; (2) Yh08 is private haplotype present in wolf populations, while the dog carrying Yh08 was the result of an ancient introgression from the wolf population. If the second hypothesis is true, then this interbreeding and consequent gene introgression included a male wolf and a female dog, which is a possible, but extremely rare event, proven to have happened in only two cases in the world so far: Vancouver Island (MUÑOZ-FUENTES et al, 2010) and Latvia (HINDRIKSON et al, 2012). The common direction of hybridization includes female wolves and male dogs (raNDI et al, 2000;ANDERSONE-LILLEY et al, 2002;VILÀ et al, 2003;VERARDI et al, 2006) and this was reconfirmed by this study.…”

An Account of the Taxonomy of North American Wolves From Morphological and Genetic Analyses

“…Coastal populations of southeast Alaska (Weckworth et al 2010) and British Columbia (Munoz-Fuentes et al 2009) share common 1o38 and unique lu68 haplotypes (Table 5) that comprise a distinct mtDNA phylogroup, inconsistent with their taxonomic distinction as different subspecies. The name Canis lupus crassodon has been used to distinguish the wolves of Vancouver Island from mainland wolves (Goldman 1944;Hall and Kelson 1959;Hall 1981 (Munoz-Fuentes et al 2010).…”

“…Wolf-dog hybridization in the wolf population of Vancouver Island was the subject of study by Munoz-Fuentes et al (2010) using microsatellites and mtDNA control-region sequence. Wolves were thought to have been extirpated from the island between 1950 and 1970, after which they recolonized from the adjacent mainland of British Columbia.…”

“…Assessments of mtDNA control-region sequence variation by Munoz-Fuentes et al (2010) detected evidence of wolf-dog hybridization in wolves that recolonized Vancouver Island after extirpation in the 1950s. The single mtDNA haplotype lu68 found in all 13 available pre-extirpation specimens (collected 1910-1950) was observed in only 5 % of the recovered Vancouver Island population and 25% of the coastal mainland population (Munoz-Fuentes et al 2009).…”

The phylogeography of red and yellow coppersmith barbets (Aves: Megalaima haemacephala)

“…In several cases different phylogenetic or phylogeographic patterns have been observed in mitochondrial and nuclear markers, mainly due to introgression of neutral mitochondrial DNA or nuclear genes with a selective advantage (Anderson et al, 2009;Muñoz-Fuentes et al, 2010;Hailer et al, 2012;Toews and Brelsford, 2012). In these cases populations that appear divergent may actually be very closely related, and vice-versa.…”