Assessing the spatial extent of wolf-dog hybridization in real-time and at population level using non-invasive DNA sampling

The crossbreed between wild species and their domestic counterparts has been described in the literature as potential threat to the species conservation, since it may lead to the disruption of local adaptations or to the genetic homogenization through introgressive hybridization. Nevertheless, some authors have been suggesting that this type of hybridization could enhance the evolutionary potential in the wild. Thus raising a controversial debate in the scientific community concerning the possible consequences of wild-domestic hybridization. In the last decade, sporadic but spatially spread reports of hybridization events between wolves (Canis lupus) and dogs (Canis lupus familiaris) have led to a growing concern among researchers, stakeholders and conservationists. However, the geographical patterns of the hybridization events at population level is rarely known, limiting the design and implementation of conservation and management measures. Therefore in this work we focused on assessing the geographic extent of hybridization events in northwestern Iberia, an area where the wolf population, despite the humandominated landscape, persisted to the severe regression that the European populations suffered. This was accomplished through a non-invasive genetic survey of an area of 5000 km, covering the territory of 13 packs including an earlier described hybrid pack. A combinations of a panel of 18 microsatellites and a fragment from the mtDNA control region was used in different Bayesian and pairwise relatedness analysis in order to properly identify hybrids and assess the dynamic of these events. From a total of 332 collected samples, we were able to identify 140 distinct individual genotypes, from which 78 were assigned to the wolf population, 58 to dog, and 4 presenting intermediate assignment values were identify as hybrids. Thus, and independently from the high presence of the domestic species in the sampling area, we were able to asses a low hybridization rate (5%), similar to a previous study for the entire Iberian Peninsula population. Also in line with previous studies, both wild and domestic populations represent independent and distinct gene pools. Additionally, the detected hybrids were dispersed throughout the sampling area, and further the identification of two distinct and spaced home-packs of two hybrids shows the spatial component of hybridization events in the sampling area. Concluding, these results show not only a previously unseen scenario of multiple and widespread hybridization events, but also support the hypothesis that wolf populations can present overlapping distributions with their domestic counterparties without having high hybridization rates or similar gene pools. Nevertheless, it is important FCUP Assessing the spatial extent of wolf-dog hybridization in real-time and at population level using non-invasive DNA sampling VI to continue improving knowledge, focusing now on better understanding the underlying process (e.g. ecological or behavior traits) of hybridization dynamics. Key-Words: Grey wolf; Domestic Dog; wolf/dog hybridization, introgression, noninvasive samples, management strategies FCUP Assessing the spatial extent of wolf-dog hybridization in real-time and at population level using non-invasive DNA sampling VII