Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Biodiversity and biogeography in heterospecific teleostean (Gadidae) - copepod (Lernaeocera) associations.

Abstract

This genetic study confirms the validity of 2 controversial parasite species, Lernaeocera branchialis and L. lusci (Copepoda, Pennellidae). These species cohabit throughout a large sector of the North Sea and the Atlantic Ocean, parasitizing Merlangius merlangus and Trisopterus luscus (Teleostei, Gadidae), respectively. In the Mediterranean Sea, it was L. branchialis that was described initially. It is shown, however, that it is L. lusci that parasitizes T. luscus and Merluccius merluccius in this geographical area. The distribution of L. lusci, as well as that of its host, T. luscus, must extend into the Mediterranean. L. lusci has colonized a phylogenetically distant host (M. merluccius) in the Mediterranean and the results show that this species has become the preferred host for the maturation of L. lusci in this region. In addition, the existence of genetic differentiation between T. luscus from the Atlantic and from the western Mediterranean is demonstrated. Thus, it is possible that the specialization of L. lusci in a new resource (M. merluccius) in the Mediterranean might be related to biological changes undergone by this copepod's original host, T. luscus. In contrast to other parasite groups such as the Monogenea, the specialization of species of the genus Lernaeocera would appear to depend more on ecological parameters (relative abundance and availability of resources) than on phylogenetic constraints. The relationships within these host-parasite systems are therefore compared with the predator-prey relationships.