Genetic evidence reveals extensive wolf-dog hybridisation in peninsular Italy: warnings against ineffective management

Wolf-dog hybridisation (WDH) - a form of anthropogenic introgressive hybridisation - may have occasionally occurred since the times of domestication. More recently, however, despite the ongoing recovery of wolf populations in Europe, the high number of domestic dogs along with marginal ecological conditions may pose increased risks to their genetic integrity. Accordingly, WDH is currently recognised among the highest threats to European wolves, with potential cascading effects through socio-ecological systems. Based on high quality DNA from tissues of 748 wolves retrieved dead from 2020 to 2024, alongside 26 additional samples from 1993 to 2003, we assessed WDH in the peninsular Italian wolf population. Using 23 autosomal STR loci and 5 Y-linked loci for males, we detected a high proportion (46.7 %) of wolves admixed with dogs, 29.5 % of which recent hybrids and 17.2 % older backcross generations. While most of the original hybridisation events likely took place some 9–16 years ago, a few first-generation hybrids in our sample indicate that WDH is currently ongoing. This seriously threatens the genetic integrity not only of the Italian wolf population, but also of the neighbouring wolf populations through dispersal events. The situation we present, which has not been previously reported for any wolf population worldwide, serves as a cautionary example of the potential dynamics of WDH in human-dominated landscapes should the issue remain persistently unaddressed. They also highlight the importance of considering the genetic constituency of wolf populations when evaluating their conservation status, especially in light of the recent downgrading of their protection status across Europe.