Unveiling an ancient biological invasion: molecular analysis of an old European alien, the crested porcupine (Hystrix cristata)

We analyzed 2,195 mitochondrial base pairs, including Cytochrome b, Control Region and rRNA 12S, in 161 Italian and 27 African specimens and assessed the ancient invasive origin of Italian crested porcupine (Hystrix cristata) populations from Tunisia. Molecular coalescent-based Bayesian analyses proposed the Roman Age as a putative timeframe of introduction and suggested a retention of genetic diversity during the early phases of colonization. The characterization of the native African genetic background revealed the existence of two differentiated clades: a Mediterranean group and a Sub-Saharan one. Both standard population genetic and advanced molecular demography tools (Bayesian Skyline Plot) did not evidence a clear genetic signature of the expected increase in population size after introduction. Along with the genetic diversity retention during the bottlenecked steps of introduction, this finding could be better described by hypothesizing a multi-invasion event.Evidences of the ancient anthropogenic invasive origin of the Italian Hystrix cristata populations were clearly shown and the native African genetic background was preliminary described. A more complex pattern than a simple demographic exponential growth from a single propagule seems to have characterized this long-term invasion.The widespread introduction of non-native species has long been regarded as one of the major anthropogenic global changes and threats to biodiversity [1,2]. The remarkable economic and ecological costs of biological invasions make the management of invaders one of the leading challenges in conservation biology [3,4]. Standard methodologies implemented in population biology and new statistical tools recently developed in genetic analysis could help elucidate features and patterns relevant to invasive biology [5]. Likewise, a comprehensive investigation of ecology and phylogeography of native source populations may suggest new insights into colonization and rapid evolutionary dynam