Evolutionary history of the genus Tarentola (Gekkota: Phyllodactylidae) from the Mediterranean Basin, estimated using multilocus sequence data

Abstract

[Background] The pronounced morphological conservatism within Tarentola geckos contrasted with a high genetic variation in North Africa, has led to the hypothesis that this group could represent a cryptic species complex, a challenging system to study especially when trying to define distinct evolutionary entities and address biogeographic hypotheses. In the present work we have re-examined the phylogenetic and phylogeographic relationships between and within all Mediterranean species of Tarentola, placing the genealogies obtained into a temporal framework. In order to do this, we have investigated the sequence variation of two mitochondrial (12S rRNA and 16S rRNA), and four nuclear markers (ACM4, PDC, MC1R, and RAG2) for 384 individuals of all known Mediterranean Tarentola species, so that their evolutionary history could be assessed.

[Results] Of all three generated genealogies (combined mtDNA, combined nDNA, and mtDNA+nDNA) we prefer the phylogenetic relationships obtained when all genetic markers are combined. A total of 133 individuals, and 2,901 bp of sequence length, were used in this analysis. The phylogeny obtained for Tarentola presents deep branches, with T. annularis, T. ephippiata and T. chazaliae occupying a basal position and splitting from the remaining species around 15.38 Mya. Tarentola boehmei is sister to all other Mediterranean species, from which it split around 11.38 Mya. There are also two other major groups: 1) the T. mauritanica complex present in North Africa and Europe; and 2) the clade formed by the T. fascicularis/deserti complex, T. neglecta and T. mindiae, occurring only in North Africa. The cladogenesis between these two groups occurred around 8.69 Mya, coincident with the late Miocene. Contrary to what was initially proposed, T. neglecta and T. mindiae are sister taxa to both T. fascicularis and T. deserti.

[Conclusions] At least in the Iberian Peninsula and Northwest Africa, the lineages obtained have some geographic coherency, whilst the evolutionary history of the forms from Northeast Africa remains unclear, with a paraphyletic T. fascicularis with respect to T. deserti. The separation between the T. mauritanica complex and the clade formed by the T. fascicularis/deserti complex, T. neglecta and T. mindiae is coincident with the uplift of the Atlas Mountain chain, and the establishment of two distinct bioclimatic regions on each side of the barrier.