Evolution, 56(12), 2002, pp. 2459±2471 COEVOLUTION BETWEEN LAMELLODISCUS (MONOGENEA: DIPLECTANIDAE) AND SPARIDAE (TELEOSTEI): THE STUDY OF A COMPLEX HOST-PARASITE SYSTEM YVES DESDEVISES,1,2,3 SERGE MORAND,1,6 OLIVIER JOUSSON,4,5,7 AND PIERRE LEGENDRE2,8 1Centre de Biologie et d'E cologie Tropicale et MeÂditerraneÂenne, UMR CNRS 5555, Universite de Perpignan, 52 Avenue de Villeneuve, F-66860 Perpignan Cedex, France 2DeÂpartement de Sciences Biologiques, Universite de MontreÂal, C.P. 6128, succursale Centre-ville, MontreÂal, QueÂbec H3C 3J7, Canada 4Station de Zoologie, DeÂpartement de Zoologie et Biologie Animale, Universite de GeneÁve, 154, route de Malagnou, CH-1224 CheÃne-Bougeries, Switzerland 5Centre d'OceÂanologie de Marseille, UMR CNRS 6540 DIMAR, Universite d'Aix-Marseille II, 13288 Marseille, France 6E-mail:
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[email protected] Abstract. Host-parasite coevolution was studied between Sparidae (Teleostei) ®shes and their parasites of the genus Lamellodiscus (Monogenea, Diplectanidae) in the northwestern Mediterranean Sea. Molecular phylogenies were re- constructed for both groups. The phylogenetic tree of the Sparidae was obtained from previously published 16S mitochondrial DNA (mtDNA) sequences associated with new cytochrome-b mtDNA sequences via a ``total evidence'' procedure. The phylogeny of Lamellodiscus species was reconstructed from 18S rDNA sequences that we obtained. Host-parasite coevolution was studied through different methods: TreeFitter, TreeMap, and a new method, ParaFit. If the cost of a host switch is not assumed to be high for parasites, all methods agree on the absence of widespread cospeciation processes in this host-parasite system.