MEPS 281:51-62 (2004)  -  doi:10.3354/meps281051

Population genetics of dwarf eelgrass Zostera noltii throughout its biogeographic range

J. A. Coyer1,*, O. E. Diekmann2, E. A. Serrão2, G. Procaccini3, N. Milchakova4, G. A. Pearson2, W. T. Stam1, J. L. Olsen1

1Department of Marine Biology, Centre for Ecological and Evolutionary Studies, University of Groningen, 9750 AA Haren, The Netherlands 2CCMAR, Center for Marine Sciences, FCMA, University Algarve, Gambelas, 8005-139 Faro, Portugal 3Stazione Zoologica, ‘Anton Dohrn’, Laboratorio di Ecologia del Benthos, Punta S. Pietro, 80077 Ischia (Napoli), Italy 4Department of Phytobenthos, Institute of Biology of the Southern Seas, Sevastopol 99011, Crimea, Ukraine

ABSTRACT: The marine angiosperm Zostera noltii (dwarf eelgrass), an important facilitator species and food source for invertebrates and waterfowl, predominantly inhabits intertidal habitats along eastern Atlantic shores from Mauritania to southern Norway/Kattegat Sea and throughout the Mediterranean, Black and Azov seas. We used 9 microsatellite loci to characterize population structure at a variety of spatial scales among 33 populations from 11 localities throughout the entire biogeographic range. Isolation by distance analysis suggested a panmictic genetic neighborhood of 100 to 150 km. At the global scale, a neighbor-joining tree based on Reynolds distances revealed strongly-supported groups corresponding to northern Europe, Mauritania and the Black/Azov Sea; separate Mediterranean and Atlantic-Iberian groups were poorly supported. Clones (genets with multiple ramets) were present in most populations but were generally small (ca. <3 m2). Exceptions were found in Mauritania (ca. 29 m in length), the Azov Sea (ca. 40 m in length) and the Black Sea (ca. 50 m in length). Although genetic diversity and allelic richness generally decreased from Mauritania to Denmark, the putative post-glacial recolonization route, both were unexpectedly high among populations from the German Wadden Sea.

KEY WORDS: Seagrasses · Zostera noltii · Genetic structure · Clonality · Genets · Ramets · Ice age · Microsatellites · Phylogeography

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