Caprella penantis Leach, 1814 and Caprella dilatata Kroyer, 1843 (Crustacea: Amphipoda) from the Strait of Gibraltar: a molecular approach to explore intra- and interspecific variation

摘要

Our knowledge of the caprellids is still fragmentary, mainly due to difficulty with the taxonomy of Caprellidae compared with other Crustacean groups. Apart from the morphological variation with age and sex, some caprellid species also show considerable intraspecific morphological variations, whereas others appear to be highly invariable. Consequently, some world-wide distributed species, such as Caprella penantis , are probably complexes of different species in which it is difficult to understand if the morphological variation is intra- or interspecific. In the present study, we revealed, for the first time in caprellids, the validity of the random amplified polymorphic DNA (RAPD) technique as a tool for helping to solve taxonomic problems. Five populations of C. penantis and two populations of the close species C. dilatata , collected from different sites of southern Spain and northern Africa, were selected for morphological and genetic study. Twenty primers were tested, and the phenogram, based on the similarity coefficient of Nei and Li and the UPGMA method, clearly separated C. penantis from C. dilatata (only 8% similarity between them), supporting the morphological differences that indicate that both species are really different and valid species. However, the five populations of C. penantis were clustered together in the RAPD analysis (85% similarity), indicating that, probably, all the specimens of C. penantis from the Strait of Gibraltar belong to the same species, in spite of the morphological variations in the pleura, gills and robustness, among populations. Future analyses should be conducted using populations of C. penantis from different areas of the world to explore if all the morphs belong to the same species.