Systematics and evolution of the libyan jird based on molecular and morphometric data

The libyan jird is one of the most widely distributed species among wild rodents, with its range extending from Morocco to China. Fifteen subspecies were described but their validity and the phylogenetic relationships among them are uncertain. Based on a comprehensive sampling, this study aims to define subspecies limits within Meriones libycus and to discuss the factors driving subspecific diversification. We used an integrative approach combining molecular (Cytochrome b and Cytochrome Oxidase Subunit 1 genes) and geometric morphometric data. Genetic data allowed us to identify three allopatric lineages within M. libycus: Western lineage in North Africa, Central lineage in Saudi Arabia, Jordan, and Syria, and Eastern lineage in Iran, Afghanistan, and China. These three lineages can also be differentiated based on skull morphology. Our results support the existence of at least three subspecies within the libyan jird: Meriones libycus libycus, M. l. syrius, and Meriones libycus erythrourus. Based on our divergence time estimates, all divergence events within M. libycus probably occurred during the Pleistocene, after 1.597 Ma. Quaternary climate fluctuations in the Sinai Peninsula explain the differentiation between the African M. l. libycus and the Levant-Arabian M. l. syrius. The differentiation of M. l. syrius with respect to the eastern M. l. erythrourus is putatively linked to the climatic fluctuations and tectonic activity of the Zagros Mountains and/or the Mesopotamia Plain of Iraq during the Pleistocene.