An integrative approach uncovered variation within Trapelus ruderatus (Olivier, 1804) (Squamata: Agamidae) in Western Asia

Abstract

The Agamid lizard Trapelus ruderatus has a large distribution in western Asia. There is as yet neither a comprehensive molecular phylogeny nor morphological variation studies on populations of this species. In the present study, we aimed to evaluate the morphology and genetic attributes of this species from populations in Iran, Turkey, Syria, and Iraq. For the morphological examination, 18 characters (nine metric, eight meristic, and one ratio characters) were examined on all specimens. The populations were divided into four Operational Taxonomic Units (OTUs; three in Iran and one in Turkey). The Iraqi population was distinguished as Trapelus persicus by morphological characters. Morphological analyses confirmed that all OTUs could be considered as distinct and that the Turkey population is clearly separated from the Iranian populations. In the genetic component of the project, two mitochondrial (Cytb and ND2) gene fragments were used to reveal phylogenetic relationships among the populations. Molecular phylogenetic reconstruction showed five distinct clades (three in Iran, one in southeastern Turkey, and one in central-southern Turkey–western Syria). Iraqi populations clustered with T. persicus, with high genetic distances from all other populations, as seen using morphological data. Based on the molecular genetic analyses, southeastern Turkey and central-southern Turkey-Syrian populations are clearly distinct (8.4% mean distance) and far from the type population in Iran. This suggests that they should be considered as different taxa. Iranian populations were differentiated into three major groups, the type population in Fars Province and two others in northwest and western Iran. The morphological and molecular genetic results gave a similar output with three Iranian populations having minor divergence, but being clearly separated from the population in Turkey. We suggest each of these groups should be considered as full species. According to divergence time estimation, T. ruderatus firstly diverged at 26.5 mya and subsequently diversified due to the uplifting of the Zagros Mountains and Anatolian Diagonal 15 mya. Subsequent aridification in the Central Iranian Plateau could also have contributed to the divergence of the Fars lineage 9.6 mya.