Taxonomic status and origin of the Egyptian weasel (Mustela subpalmata) inferred from mitochondrial DNA
Résumé
The Egyptian weasel (Mustela subpalmata) is a small mustelid with a distribution restricted to the lower Nile Valley and the Nile Delta. Traditionally considered a subspecies of the least weasel (M. nivalis), it is currently recognized as a separate species based on morphology. Here we present the first genetic assessment of the taxonomic status of the Egyptian weasel by comparing mitochondrial DNA (Cytochrome b gene and control region) sequences to those of least weasels from the western Palearctic, with a focus on the Mediterranean region. Our results provide no evidence to support the view that the Egyptian weasel is genetically distinct from the least weasel, as we found that, for both Cytochrome b and control region, haplotypes were shared between the two taxa. Specifically, the Cytochrome b and control region haplotypes detected in the Egyptian weasel were also present in M. nivalis from Turkey and Malta, two populations genetically analysed here for the first time. Our results suggest that the Egyptian weasel is distinct from the least weasel populations currently living in the Maghreb, which were inferred to be the result of an earlier colonization of North Africa, but the genetic data alone do not allow us to determine whether the Egyptian weasel is native or introduced. Nevertheless, the observed genetic patterns, together with the weasel fossil record in Israel and the unique commensal lifestyle of the Egyptian weasel, are consistent with the hypothesis that the Egyptian population is a relict of past range expansion from the Levant into Egypt. We suggest that the large size and characteristic sexual dimorphism of the Egyptian weasel are likely to represent ecotypic variation, but genomic studies are required to clarify the extent of its functional genetic divergence.