Tracing historical introductions in the Mediterranean Basin: the success story of the common genet (Genetta genetta) in Europe

The successful introduction of the common genet (Genetta genetta) into Europe has been traditionally associated to the Muslim invasion of Iberia, although diverse evidence suggested an earlier arrival. In this study, we assessed genetic variation at 11 microsatellite loci in 199 individuals from the Mediterranean Basin and used approximate Bayesian computation (ABC) combining genotypes and published mitochondrial sequences. Our objectives were to (1) test alternative scenarios of introduction of the species in Europe, (2) re-assess the mitochondrial signatures of ‘introduction hotspots’ in Iberia, and (3) evaluate how post-introduction demographic processes have shaped genetic structure in the invaded range. ABC estimates favored a scenario of independent introductions from Maghreb into the Balearic Isl. and Iberia; the latter was dated between the Upper Palaeolithic and the end of Phoenicians’ influence. Patterns of genotypic diversity broadened the Andalusian introduction hotspot to the antique Tartessos Kingdom and suggested multiple introductions and/or long-term genetic drift. The best fit ABC scenario implied a natural spread from Iberia to France, but was in potential conflict with our delimitation of two genetic clusters (France and Iberia) in continental Europe. In fact, southwestern France populations showed a fair proportion of alleles shared with Maghreb and low levels of heterozygosity that may reflect subsequent introduction from Iberia, in line with the high error rates in favor of this alternative scenario. Significant patterns of isolation-by-distance among individuals within both genetic clusters are suggestive of natural dispersal from both Iberian and French introduction sites resulting in a secondary contact zone in northern Iberia. Overall, our study strongly suggests that the common genet was intentionally introduced in southern Iberia at a time antedating the Muslim invasion, possibly via Phoenicians’ commercial routes. Subsequent introduction in France, long-term genetic drift and admixture likely shaped the species genetic variation currently observed in continental Europe