Evolution around the Red Sea: Systematics and biogeography of the agamid genus Pseudotrapelus (Squamata: Agamidae) from North Africa and Arabia

Since the Oligocene, regions adjacent to the Red Sea have experienced major environmental changes, from tectonic movements and continuous geological activity to shifting climatic conditions. The effect of these events on the distribution and diversity of the regional biota is still poorly understood. Agamid members of the genus Pseudotrapelus are diurnal, arid-adapted lizards distributed around the Red Sea from north-eastern Africa, across the mountains and rocky plateaus of the Sinai and Arabian Peninsulas northwards to Syria. Despite recent taxonomic work and the interest in the group as a model for studying biogeographic and diversity patterns of the arid areas of North Africa and Arabia, its taxonomy is poorly understood and a comprehensive phylogeny is still lacking. In this study, we analyzed 92 Pseudotrapelus specimens from across the entire distribution range of the genus. We included all known species and subspecies, and sequenced them for mitochondrial (16S, ND4 and tRNAs) and nuclear (MC1R, c-mos) markers. This enabled us to obtain the first time-calibrated molecular phylogeny of the genus, using gene trees, species trees and coalescent-based methods for species delimitation. Our results revealed Pseudotrapelus as a monophyletic genus comprised of two major clades and six independently evolving lineages. These lineages correspond to the five currently recognized species and a sixth lineage relating to the synonymized P. neumanni. The subspecific validity of P. sinaitus werneri needs further assessment as it does not form a distinct cluster relative to P. s. sinaitus. The onset of Pseudotrapelus diversification is estimated to have occurred in Arabia during the late Miocene. Radiation has likely resulted from vicariance and dispersal events due to the continued geological instability, sea level fluctuations and climatic changes within the region.This work was funded by grant CGL2012-36970 from the Ministerio de Economía y Competitividad, Spain (co-funded by FEDER – EU). Field work in Oman in 2013 was partially supported by the project “Field study for the conservation of reptiles in Oman” funded by the Ministry of Environment and Climate Affairs, Oman (Ref: 22412027), and collecting permit 31/2012 issued for SS. KT is supported by the Steinhardt Museum of Natural History, Israel National Center for Biodiversity Studies, Tel Aviv University, Israel.Peer reviewe