a1 UPMC Univ Paris 06, UMR 7628, Modèles en biologie cellulaire et évolutive, Laboratoire Arago, Avenue Fontaulé, BP44, F-66651 Banyuls-sur-Mer, France
a2 CNRS, UMR 7628, Modèles en biologie cellulaire et évolutive, Laboratoire Arago, Avenue Fontaulé, BP44, F-66651 Banyuls-sur-Mer, France
a3 UMR 5244 CNRS-EPHE-UPVD, Biologie et Ecologie Tropicale et Méditerranéenne, Parasitologie Fonctionnelle et Evolutive, Université Via Domitia, 52 Avenue Paul Alduy, F-66860 Perpignan Cedex, France
We investigated whether host specificity is linked to variability within species of Lamellodiscus monogeneans, which are gill ectoparasites of the Sparidae. We sampled fish parasites in the northeastern part of the Mediterranean Sea: 4 specialist species, using 1 single host species, and 3 generalist species, using 2 distinct host species. Intraspecific variability was assessed from 2 different datasets. Morphometric variability of the attachment organ, called the haptor, was estimated first from measurements of several sclerified haptoral parts on 102 individuals. Genetic variability was calculated based on comparisons of sequences derived from the first internal transcribed spacer (ITS-1) of nuclear ribosomal DNA of 62 individuals. Morphometric variances in the specialist versus generalist species were compared via principal component analysis and F-tests, and uncorrected genetic distances (p-distances) were estimated within each species. We showed that the inter-individual variance of morphometric characters, as well as p-distances, are clearly greater within generalist species than specialist ones. These findings suggest that a relative increase in morphological and molecular variability enhances the possibility to colonize new host species in monogeneans, and supports the hypothesis that intraspecific variability could be a potential determinant of host specificity.
(Received December 21 2007)
(Revised January 22 2008)
(Accepted January 24 2008)
c1 Corresponding author: UPMC Univ Paris 06, UMR 7628, Modèles en biologie cellulaire et évolutive, Laboratoire Arago, Avenue Fontaulé, BP44, F-66651 Banyuls-sur-Mer, France. Tel: +33 4 68 88 73 13. Fax: +33 4 68 88 16 99. E-mail: firstname.lastname@example.org