Spatial assessment of wolf-dog hybridization in a single breeding period

Abstract

Understanding the dynamics of wolf-dog hybridization and delineating evidence-based conservation strategies requires information on the spatial extent of wolf-dog hybridization in real-time, which remains largely unknown. We collected 332 wolf-like scats over ca. 5,000km2 in the NW Iberian Peninsula to evaluate wolf-dog hybridization at population level in a single breeding/pup-rearing season. Mitochondrial DNA (MtDNA) and 18 ancestry informative markers were used for species and individual identification, and to detect wolf-dog hybrids. Genetic relatedness was assessed between hybrids and wolves. We identified 130 genotypes, including 67 wolves and 7 hybrids. Three of the hybrids were backcrosses to dog whereas the others were backcrosses to wolf, the latter accounting for a 5.6% rate of introgression into the wolf population. Our results show a previously undocumented scenario of multiple and widespread wolf-dog hybridization events at the population level. However, there is a clear maintenance of wolf genetic identity, as evidenced by the sharp genetic identification of pure individuals, suggesting the resilience of wolf populations to a small amount of hybridization. We consider that real-time population level assessments of hybridization provide a new perspective into the debate on wolf conservation, with particular focus on current management guidelines applied in wolf-dog hybridization events.

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

“…This suggests that the power to identify introgression in many other studies may have been limited because of the low number of markers or due to the generalized introgression of one gene pool into the other (see Sanchez‐Donoso et al., ). Consequently, previous estimates of introgression rates in European wolf populations should be taken with caution (Godinho et al., ; Pacheco et al., ; Verardi, Lucchini, & Randi, ; Vilà, Sundqvist, et al., ; Vilà, Walker, et al., ). A frequent pattern emerging from most of these studies was the identification of a larger number of F1 hybrids compared to a small proportion of later‐generation back‐crosses (that would indicate the introgression of dog genes into the wolf population).…”

Use of hidden Markov capture–recapture models to estimate abundance in the presence of uncertainty: Application to the estimation of prevalence of hybrids in animal populations

“…We set the thresholds for the three categories based on the genetic clustering analyses performed on simulated genotypes by Pacheco et al. (), see Fig. in the Supplementary Materials of Pacheco et al.…”

“…in the Supplementary Materials of Pacheco et al. (). We considered as pure wolves those individuals whose q wolf was included in the range of q wolf values of simulated pure wolves genotypes and did not overlap with that of simulated backcrosses (hybrid × parental).…”

“…We distinguished wolves, hybrids, and uncertain individuals based on their membership proportions to the wolf cluster (q wolf ) and 90% Bayesian credible intervals (BCI). We set the thresholds for the three categories based on the genetic clustering analyses performed on simulated genotypes by Pacheco et al (2017), see Fig. S1 in the Supplementary Materials of Pacheco et al (2017).…”

“…We set the thresholds for the three categories based on the genetic clustering analyses performed on simulated genotypes by Pacheco et al (2017), see Fig. S1 in the Supplementary Materials of Pacheco et al (2017). We considered as pure wolves those individuals whose q wolf was included in the range of q wolf values of simulated pure wolves genotypes and did not overlap with that of simulated backcrosses (hybrid × parental).…”