gions in western Asia could have served as climate refugia for forest vegetation during the Last Glacial Maximum (LGM): Colchis, western Anatolia, western Taurus, upper reaches of the Tigris River, Levant, and the southern Caspian basin

the Quaternary climatic oscillations and persist today in isolated refugial areas is crucial for maintaining the global diversity of plants, especially considering the current climate trend of increasing temperatures and water stress ( Petit et al., 2005 ; Kozlowski et al., 2012 ). The Arcto-Tertiary relict fl ora, that covered large parts of the northern hemisphere during the Eocene but since the Miocene has moved southward due to a shift toward a dryer and cooler climate ( Chaney, 1947 ; Milne and Abbott, 2002 ; Milne, 2006 ), is represented today by many temperate tree genera, among which Zelkova gained a particular interest in the recent years ( Fineschi et al., 2002 ; Denk and Grimm, 2005 ; Kvavadze and Connor, 2005 ; Søndergaard and Egli, 2006 ; Garfi et al., 2011 ; Kozlowski et al., 2012 ; Christe et al., 2014 ). The fossil record supports the past wide distribution of the genus ( Wang et al., 2001 ; Denk and Grimm, 2005 ) and its extinction in North America, North Africa, and Europe as a result of climatic shifts in the Quaternary period ( Chaney, 1947 ; Kvavadze and Connor, 2005 ). The last appearances of Zelkova in mainland Europe were in Rome (Italy) and date back to 31 thousand years ago (ka) ( Follieri et al., 1986 ). Zelkova carpinifolia (Pall.) C. Koch. is the only species of the genus Zelkova that occurs in western Asia. The remaining Zelkova species are restricted to Mediterranean islands or have a wider distribution in East Asia. It has been shown that six regions in western Asia could have served as climate refugia for forest vegetation during the Last Glacial Maximum (LGM): Colchis, western Anatolia, western Taurus, upper reaches of the Tigris River, Levant, and the southern Caspian basin ( Tarkhnishvili et al., 2012 ). There are two relict forest regions in the Caucasus and adjacent areas: the Hyrcanian forest on the southern coast of the Caspian Sea, bounded by the Talysh and Alborz mountain ranges, and the Colchic forest on the eastern coast of the Black Sea, bounded by the western Greater and Lesser Caucasus mountains and the Likhi Ridge ( Nakhutsrishvili et al., 2011 ). Zelkova carpinifolia occurs naturally in the Hyrcan region of Azerbaijan and Iran and the Colchis of western 1 Manuscript received 25 August 2014; revision accepted 2 December 2014. The authors thank I. Huseynova, V. Alizade, E. Alirzayeva, and A. Mutallimov (Institute of Botany, Azerbaijan); E. Gerber and R. Keller (Natural History Museum, Switzerland); D. Frey (University of Fribourg, Switzerland); G. Parolly and N. Korotkova (Botanical Garden and Botanical Museum Berlin, Germany); M. Jafari (University of Tehran, Iran); M. Amini Rad (Iranian Research Institute of Plant Protection, Iran); and I. Kaya (Yuzuncuyil University, Turkey) for the organization and coordination of fi eldwork. The study was carried out in the framework of the project “Developing tools for conserving the plant diversity of the Transcaucasus” funded by the Volkswagen Foundation. 8 Author for correspondence (e-mail: [email protected]) ANALYSIS OF NUCLEAR MICROSATELLITES REVEALS LIMITED DIFFERENTIATION BETWEEN COLCHIC AND HYRCANIAN POPULATIONS OF THE WIND-POLLINATED RELICT TREE ZELKOVA CARPINIFOLIA (ULMACEAE) 1