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Systematics and Phytogeography |
2 Department of Systematic and Evolutionary Botany, Institute of Botany, University of Vienna, Rennweg 14, A-1030 Vienna, Austria 3 Departamento de Biología Vegetal y Ecología, Facultad de Biología, Universidad de Sevilla, Apartado 1095 41080-Sevilla, Spain 4 INRA, UMR 1202 BIOGECO, 69, Route dArcachon, F-33612 Cestas Cedex, France 5 Institut Méditerranéen dEcologie et de Paléoécologie, Faculté des Sciences de St-Jérôme, Boite 462, Av. Escadrille Normandie-Niemen, F 13397 Marseille Cedex 20, France
ABSTRACT
Northwest Africa is a major hotspot of plant biodiversity, but very little is known about the Quaternary range dynamics of plant species in this region. Here we investigate the range-wide population structure and phylogeography of Atlas cedar (Cedrus atlantica), an emblematic forest tree endemic to Morocco and Algeria. We genotyped 261 individuals from 11 populations using AFLP markers. Data were analyzed using both conventional FST-based techniques and Bayesian clustering. Overall population differentiation was high (FST = 0.25). Two major groups of populations were identified, one distributed through the Rif and Middle Atlas mountains in Morocco and the other through the Algerian Tell Atlas and Aurès mountains as well as the Middle Atlas. Combined molecular and fossil data indicate that C. atlantica survived the Last Glacial Maximum in at least three disjunct refugia along the coast of the Mediterranean Sea, whereas the Middle Atlas, today the core of the species range, has been colonized relatively recently (<10000 yr BP). The colonization history of individual populations has left clear imprints in their present-day diversity, which may vary greatly even between nearby stands. Our study illustrates how integrating different data sources and analytical approaches can help elucidate complex range dynamics that would otherwise remain undeciphered.
Key Words: Algeria AFLP diversity gene flow glacial refugia Morocco nonmetric multidimensional scaling analysis population divergence range contraction Structure program
Received for publication 11 January 2008. Accepted for publication 8 July 2008.
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