Using a phylogeographic approach to investigate the diversity and determine the distributional range of an isopod (Crustacea: Peracarida), Stenosoma nadejda (Rezig, 1989) in the Atlantic-Mediterranean region

• Published in: Hydrobiologia 2016-03, Vol.768 (1), p.315-328
• Main Authors: Xavier, Raquel, Branco, Madalena, dos Santos, António Múrias
• Format: Article
• Language: English
• Subjects: Animal populations; Biomedical and Life Sciences; Crustacea; Crustaceans; Cryptic species; cytochrome-c oxidase; Dispersal; Ecology; Freshwater & Marine Ecology; Genetic diversity; genetic variation; Haplotypes; Isopoda; Life Sciences; Marine; nucleotide sequences; Peracarida; phylogeny; Phylogeography; Primary Research Paper; Swimming; Zoology
• ISSN: 0018-8158; 1573-5117
• DOI: 10.1007/s10750-015-2559-8

The genus Stenosoma comprises 13 species in the NE Atlantic, Mediterranean and Black Sea. Recent studies have improved knowledge on the distributional patterns of the genus, reducing species ranges and allowing the identification of cryptic species. Lacking a free-swimming life-stage, Stenosoma typically display small- to medium-sized ranges, with the exception of S. nadejda which occurs in the Atlantic-Mediterranean region. In this study, we build upon previous work and examine phylogeographic patterns of S. nadejda throughout its entire range to assess levels of genetic differentiation and evidence of cryptic species. While Elongation Factor 1α gene sequences revealed an almost absence of genetic and geographic structure across the entire distribution of S. nadejda, the Cytochrome c oxidase subunit I gene sequences revealed a phylogenetic split defining two Mediterranean clades. Our results confirm the wide distribution of S. nadejda in the Atlantic/Mediterranean region and show that the distribution of the two Mediterranean clades does not match the east–west break in genetic continuity typically displayed by many species. This pattern is probably a consequence of sporadic long-distance dispersal by rafting. Conversely, an almost absence of shared haplotypes at the local level, conforms to the recognized poor ability of peracarids for autonomous dispersal.