Phylogenetic Relationships among Agamid Lizards of theLaudakia caucasiaSpecies Group: Testing Hypotheses of Biogeographic Fragmentation and an Area Cladogram for the Iranian Plateau

Phylogenetic relationships within theLaudakia caucasiaspecies 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), tRNA^Gln, tRNA^Ile, tRNA^Met, ND2, tRNA^Trp, tRNA^Ala, tRNA^Asn, tRNA^Cys, tRNA^Tyr, and COI (subunit I of cytochromecoxidase). The aligned sequences contain 207 phylogenetically informative characters. Three hypotheses for historical fragmentation ofLaudakiapopulations 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 suggests the latter hypothesis, and statistical tests reject the other two hypotheses. 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.