© 2004 The American Genetic Association
Brief Communication |
Reduced Female Gene Flow in the European Flat Oyster Ostrea edulis
From IFREMER, Laboratoire Génétique et Pathologie, 17390 La Tremblade, France (Diaz-Almela, Boudry, Launey, and Lapègue), and UMR 5171 (IFREMER–CNRS–Université Montpellier II), S.M.E.L., 1, quai de la Daurade, 34200 Sète, France (Diaz-Almela, Launey, and Bonhomme). E. Diaz-Almela is currently at the Instituto Mediterráneo de Estudios Avanzados, C/Miquel Marqués no. 21, 07190 Esporles, Mallorca, Spain. S. Launey is currently at the Laboratoire de génétique des poissons, INRA, Domaine de Vilvert, 78352 Jouy en Josas, France
Address correspondence to Sylvie Lapègue at the address above, or e-mail: sylvie.lapegue{at}ifremer.fr.
The geographical structure of 15 natural populations of the flat oyster (Ostrea edulis L.) was assessed by single-strand conformation polymorphism (SSCP) of a 313-base-pair (bp) fragment of the mitochondrial 12S-rRNA gene. Fourteen haplotypes were observed, with one being dominant in the Mediterranean samples and another one in the Atlantic populations. The geographically extreme populations sampled in Norway and the Black Sea appeared differentiated by exhibiting the dominance of a third group of haplotypes. The results were compared to available microsatellite data at five loci. The Atlantic/Mediterranean differentiation pattern was qualitatively the same with both types of markers, confirming an isolation-by-distance pattern. The average mitochondrial haplotypic diversity displayed a high among populations variance, reflecting small effective population size in some locations. Additionally, a 10-fold quantitative difference was observed in Fst between the mitochondrial and the nuclear genomes, which could be due to an unbalanced sex ratio or sex-biased differential reproductive success between males and females (or both).