Mitochondrial DNA diversity in the populations of great gerbils, Rhombomys opimus, the main reservoir of cutaneous leishmaniasis

Accurate identification of animal reservoirs of transmissible diseases is an absolute requirement to any epidemiological survey of zoonoses and is essential for predicting species-specific population outbreaks and therefore to develop accurate ecological control strategies. The systematic status of the great gerbil (Rhombomys opimus) remains unclear, despite the fundamental role of these rodents as the main known reservoir hosts of the protozoan parasite Leishmania major in the epidemiology of zoonotic cutaneous leishmaniasis (ZCL) in central and south Asia. In the present work, we represent molecular evidence supporting the identification of at least two major lineages (subspecies) within the species of R. opimus in Iran. Analysis of the mitochondrial cytochrome b (cyt b) gene, revealed a range of 1–10% genetic variation among populations, which were well associated with biogeographic origins and subspecies. Results of laboratory cross hybridization between the subspecies and finding sympatric haplotypes of the two subspecies suggested that no pre- or post-zygotic barriers exist between the subspecies indicating that they still belong to a single taxon. However, the amount of genetic variations between populations/subspecies is high enough to lead them to speciation in future. Implications of such findings on the eco-epidemiology of ZCL in Iran are discussed.