NOTE Testing Hypotheses of Vicariance in the Agamid Lizard Laudakia caucasia from Mountain Ranges on the Northern Iranian Plateau J. Robert Macey,* ,1 James A. Schulte II,* Haji G. Kami,† Natalia B. Ananjeva,‡ Allan Larson,* and Theodore J. Papenfuss§ *Department of Biology, Campus Box 1137, Washington University, St. Louis, Missouri 63130-4899; †Department of Biology, Faculty of Sciences, University of Agricultural Sciences and Natural Resources, P.O. Box 49165, Gorgan, Iran; ‡Zoological Institute, Russian Academy of Sciences, 1 Universitetskaya nab., 199034, St. Petersburg, Russia; and §Museum of Vertebrate Zoology, University of California, Berkeley, California 94720 Received May 10, 1999; revised August 4, 1999 The Laudakia caucasia species group of the Iranian Plateau is a model system for historical biogeography. Tectonic activity caused by collision of the Indian and Arabian plates with Eurasia has compressed interven- ing Iranian plates on which the L. caucasia species group is endemic, producing mountain barriers that geographically fragment these populations. L. caucasia occurs on the northern margin of the Iranian Plateau, which has been uplifting for the last 5 million years (Sborshchikov et al., 1981), forming three major moun- tain chains (Fig. 1): (1) west of the Caspian Sea, the Lesser Caucasus of the Iranian Plateau connects to the Greater Caucasus; (2) the Elburz Range of Iran is situated directly south of the Caspian Sea; (3) the Kopet-Dagh and Balkhan mountains of Turkmenistan and northeast Iran rise to the east of the Caspian Sea. Macey et al. (1998) examined populations of L. cauca- sia, L. erythrogastra, and L. microlepis, the three species in the group, and reported a fully resolved phylogenetic estimate with every branch well sup- ported (minimum bootstrap of 98% and a decay index of at least 4). That study suggests an east-to-west pattern of fragmentation of populations along the northern margin of the Iranian Plateau, with a major break separating populations occurring in the greater and lesser Caucasus from Turkmen populations in the Balkhan and Kopet-Dagh mountains. Here, we report the phylogenetic position of L. caucasia from the Elburz Range located between these two montane regions, plus a new sample from the Lesser Caucasus of Geor- gia. The new samples are from Baladeh (36° 12' N 51° 48' E) road, 12 km E. of Jct with Karaj (35° 48' N 50° 59' E) to Chalus (36° 38' N 51° 26' E) road, Mazan- daran Province, Iran (population 9 in Fig. 1, uncata- logued specimen of the sixth author being deposited at the Museum of Vertebrate Zoology, MVZ-TP24781, AF172704), and from just south of the botanical gar- dens, southern hills of Tbilisi (41° 42' N 44° 45' E), Georgia (population 8 in Fig. 1, deposited at the Mu- seum of Vertebrate Zoology, MVZ 218720, AF172705). We investigate three hypotheses for historical frag- mentation of L. caucasia from the three major moun- tain chains of the northern Iranian Plateau (Fig. 1): (1) the first phylogenetic divergence occurs in the east and separates Kopet-Dagh and Balkhan populations from the more western populations in the Elburz and Cauca- sus; (2) the earliest divergence occurs in the west and separates Caucasus populations from the more eastern populations in the Elburz, Kopet-Dagh, and Balkhans; and (3) the earliest divergence occurs in the south and separates the Elburz population from the more north- ern populations in the Caucasus, Kopet-Dagh, and Balkhans. The first hypothesis is compatible with our original suggestion of an east-to-west pattern of frag- mentation of populations and species (L. caucasia and L. erythrogastra) in the mountain ranges of the north- ern Iranian Plateau. The second hypothesis indicates successive periods of fragmentation first in the east and then in the far west. The third hypothesis requires a more recent dispersal event across the Caspian Sea during periods of lower sea level following vicariant separation of populations. Mitochondrial DNA sequences [1722 aligned bases 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 cytochrome c oxidase)], were obtained 1 To whom correspondence should be addressed. Fax: (314) 935- 4432. E-mail: macey@biology.wustl.edu. Molecular Phylogenetics and Evolution Vol. 14, No. 3, March, pp. 479–483, 2000 doi:10.1006/mpev.1999.0722, available online at http://www.idealibrary.com on 479 1055-7903/00 $35.00 Copyright  2000 by Academic Press All rights of reproduction in any form reserved.