Conflicting patterns of nucleotide diversity between mtDNA and nDNA in the Moorish gecko, Tarentola mauritanica.

The gecko Tarentola mauritanica is a Mediterranean species that is widely distributed across southern Europe and North Africa. Initial phylogeographic studies based on mtDNA concluded that the European populations originated from recent colonizations from North Africa, possibly involving man-mediated introductions. A distinct lineage, found to be a sister taxon to the widespread European lineage, was subsequently reported from parts of the Iberian Peninsula. Like many gecko species, T. mauritanica contains several deep intraspecific genetic lineages within North Africa. However, in contrast to this diversity, a single mtDNA haplotype is widespread across a large part of its European range. In this work, we analysed a total of 834 base pairs from two mtDNA genes (12SrRNA and 16SrRNA) for 154 specimens, and a total of 1876bp from three nuclear genes (ACM4, MC1R and Rag2) for 51 specimens to test the phylogenetic and phylogeographic patterns proposed for T. mauritanica based on mtDNA sequences. The mtDNA results reveal a Moroccan lineage basal to the common "European" haplotype, thus suggesting that the latter probably originated in Morocco. The remaining lineages obtained are the same as those observed in previous studies. In contrast, the nDNA data do not support the majority of the mtDNA phylogenetic relationships, possibly due to incomplete lineage sorting of these markers. Moreover, the mtDNA data suggest that the Iberian clade seems to have undergone a population expansion. Surprisingly, the European clade presents a higher nucleotide diversity for the nuclear genes when compared to the combined mtDNA dataset. These analyses suggest that the low mtDNA variability that characterises the European populations of T. mauritanica is the result of a selective sweep process and not solely due to a recent colonization event.