Phylogenetic relationships among Agamid lizards of the Laudakia caucasia species group: testing hypotheses of biogeographic fragmentation and an area cladogram for the Iranian Plateau.

Phylogenetic relationships within the Laudakia caucasia species group on the Iranian Plateau were investigated using 1708 aligned bases of mitochondrial DNA sequence from the genes encoding ND1 (subunit one of NADH dehydrogenase), tRNAGln, tRNAIle, tRNAMet, ND2, tRNATrp, tRNAAla, tRNAAsn, tRNACys, tRNATyr, and COI (subunit I of cytochrome c oxidase). The aligned sequences contain 207 phylogenetically informative characters. Three hypotheses for historical fragmentation of Laudakia populations on the Iranian Plateau were tested. In two hypotheses, fragmentation of populations is suggested to have proceeded along continuous mountain belts that surround the Iranian Plateau. In another hypothesis, fragmentation is suggested to have resulted from a north-south split caused by uplifting of the Zagros Mountains in the late Miocene or early Pliocene [5-10 MYBP (million years before present)]. The shortest tree suggest the later hypothesis, and statistical tests reject the other two hypothesis. The phylogenetic tree is exceptional in that every branch is well supported. Geologic history provides dates for most branches of the tree. A plot of DNA substitutions against dates from geologic history refines the date for the north-south split across the Iranian Plateau to 9 MYBP (late Miocene). The rate of evolution for this segment of mtDNA is 0.65% (0.61-0.70%) change per lineage per million years. A hypothesis of area relationships for the biota of the Iranian Plateau is generated from the phylogenetic tree.