Phylogeography and population structure of the Western European hedgehog across Italian islands and mainland

The Western European hedgehog (Erinaceus europaeus) serves as a key model for understanding post-glacial recolonization and the impact of geographic isolation on small mammal biodiversity. Despite its broad distribution, the genetic characterization of the Italian populations remains fragmentary. This study provides a comprehensive assessment of the genetic diversity and phylogeographic structure of E. europaeus across the Italian Peninsula and five Mediterranean islands (Sicily, Sardinia, Corsica, Elba, and Pianosa). Through the analysis of 19 nuclear microsatellites and mitochondrial DNA control region sequences from 210 specimens, we identified seven distinct genetic clusters. Nuclear data revealed a relatively homogeneous genetic structure across the Italian Peninsula, with only subtle differentiation in northeastern Italy, whereas mitochondrial DNA corroborated the Southern Mediterranean refugia hypothesis. In contrast, the Sicilian population emerged as a highly divergent and ancient lineage, consistent with previous studies supporting its independent evolutionary history and its recognition as an Evolutionarily Significant Unit (ESU). Furthermore, insular populations in Sardinia and Corsica show signatures of more recent human-mediated colonization, whereas the population on Pianosa is consistent with a history of translocation. These results underscore the importance of Mediterranean islands as reservoirs of unique genetic variation and highlight the complex interplay between historical glacial refugia, post-glacial recolonization, and recent anthropogenic influences in shaping the genetic landscape of E. europaeus in the Mediterranean basin.