Molecular taxonomy and population structure of the rough-toothed dolphin Steno bredanensis (Cetartiodactyla: Delphinidae)

Abstract

Several delphinid species have shown genetic population structure, both between and within ocean basins. We investigated genetic differentiation in the rough-toothed dolphin, Steno bredanensis, using mitochondrial control region sequences from several localities worldwide (N=112). Preliminary analyses indicated high levels of genetic differentiation between the Atlantic and Pacific/Indian Oceans, which were further investigated using complete cytochrome b sequences and mitogenomes. Phylogenetic analyses were inconclusive about the existence of cryptic speciation in the genus Steno. Notwithstanding this result, analysis of molecular variance and Φ-statistics analyses revealed strong population differentiation not only between the Atlantic and Pacific, but also within the Atlantic, where three populations were detected: Caribbean, southeastern Brazil, and southern Brazil. We propose that these populations be considered management units for conservation purposes. Our results provide the first perspective on the worldwide genetic differentiation of S.bredanensis.