We analyzed whole-genome data from Italian wolves and dogs to assess the extent, timing, and functional relevance of dog introgression in the Italian wolf. Five wolves showed recent admixture within the last 3–7 generations, while historical introgressions under selection dated to the Bronze and Middle Ages involved genes linked to neuronal plasticity, vision, and immune response. These findings suggest that even limited dog ancestry may leave lasting genomic and phenotypic imprints on wild wolf populations.
Introgression resulting from anthropogenic hybridization may shape phenotypic traits in wild taxa, potentially altering species' ecology and human-wildlife interactions. This is particularly relevant in large carnivores such as gray wolves (Canis lupus) that are expanding into human-dominated landscapes. A notable example is the Italian wolf (C. l. italicus), which, after recovering from near extinction, now faces locally high levels of hybridization with the domestic dog (C. l. familiaris). Although wolf-dog hybridization is known to affect morphology, its effect on other phenotypic traits remains poorly investigated. We analyzed worldwide-distributed wolf and dog whole-genome data to assess the extent and timing of dog ancestry in a sample of 17 Italian wolves, and to explore dog introgression at behavior-related genes. Five Italian wolves, exhibiting varying levels of genome-wide dog ancestry (1-20%), were estimated to result from admixture events that occurred at least 3-7 generations before sampling (2005-2012). No overrepresentation of recent dog introgressions in behavior-related genes of admixed Italian wolves was detected. However, we identified signals of historical dog introgressions under putative selection, involving genes linked to neuronal plasticity, photoreceptor development, and immune responses. One of such introgressions likely occurred ~4,500 years ago during the Bronze Age and the other one ~1,000 years ago during the Middle Ages, suggesting that historical admixture might have shaped the Italian wolf evolutionary trajectories. Although preliminary and warranting further analyses, our results highlight the potential for phenotypic effects of wolf-dog hybridization to persist across generations, showing that even limited non-native ancestry can leave significant genomic footprints in wild populations.