The ant Anochetus ghilianii (Hymenoptera, Formicidae), not a Tertiary relict, but an Iberian introduction from North Africa: Evidence from mtDNA analyses

Abstract

Anochetus ghilianii is the only species of the genus Anochetus found in Europe. Its presence in the southernmost region of the Iberian Peninsula (Province of Cadiz) is puzzling. Anochetus ghilianii's poor dispersal capabilities (colony foundation by foot and wingless queens) suggest that its presence in the Iberian Peninsula must be ancient, dating to from at least the last connection period between both Spain and Africa around 5 million years ago. In the Iberian Peninsula, this species is only found at low altitude coastal localities, whereas its mainland counterpart populations of North Morocco show a more widespread distribution, also found at higher altitude inland. In this study, we sequenced a fragment of a rapidly evolving mitochondrial gene (COI) from several individuals throughout the species' Moroccan and Iberian distribution range. The results from the Bayesian Inference (BI) and Median-Joining analyses showed a genetic pattern of decreasing haplotypic diversity from southern to northern localities. Furthermore, our results recovered the same haplotype from all the Iberian localities and from Cap Spartel and Tangier in North Morocco. We attribute this lack of genetic divergence to multiple reoccurring translocations through maritime traffic between ports on either side of the Strait of Gibraltar. Our study raises the concern that two other ants, Technomyrmex vexatus and Stigmatomma emeryi, also believed to be Tertiary relicts with a similar distribution pattern to A. ghilianii, may have also been introduced accidentally in the Iberian Peninsula.