Genetic diversity ofsp. A (Nematoda: Anisakidae) parasitizing the European Shagfrom the Spanish Mediterranean coast.

Abstract

Sibling species of the(s.l.) complex are habitual endoparasites of cormorants of the Phalacrocoracidae family, worldwide. In Europe, the two species,sp. A andsp. B, have been identified. However, information regarding the occurrence and distribution of these anisakids in cormorants from Spain is scarce. In the present study, 20 specimens of the European Shag,, from the western Mediterranean Spanish marine coast were parasitologically analyzed for the presence of nematodes. All hosts were found parasitized withspecimens (= 1,517). A representative subsample was genetically identified assp. A by sequence analysis of the mtDNA2 gene and the ITS1 and ITS2 regions of the rDNA. This represents the first report ofsp. A from the Spanish Mediterranean waters. Population genetic analysis was performed including othersp. A specimens from the west Sardinian and the Tyrrhenian Sea. At the intraspecific level, a significant genetic differentiation (&#x2248; 0.08,< 0.00001) between the metapopulation from the Spanish Mediterranean coast and that from the Sardinian waters was observed; whereas, no differentiation was found between metapopulations of the parasite from the Spanish and the Tyrrhenian Italian coast. The findings highly support the hypothesis of the adaptation of the life cycle ofsp. A in brackish and marine ecosystems. Furthermore, the results on the population genetics ofsp. A suggest the possible role of the migration routes of wintering populations of cormorants in the Mediterranean Sea in influencing the parasite genetic structure.