Amaral, A.R.,Beheregaray, L.B.,Sequeira, M.,Robertson, K.M.,Coelho, M.M., Möller, L.M. Worldwide Phylogeography of the genus Delphinus revisited Technical Report (7), 2009, ISBN: SC/61/SM11. Abstract | BibTeX | Keywords: Arabian Sea, Common dolphin, delphinus capensis, Delphinus delphis, delphinus sp., genetics, Indian Ocean, taxonomy @techreport{, title = {Worldwide Phylogeography of the genus Delphinus revisited}, author = {Amaral, A.R.,Beheregaray, L.B.,Sequeira, M.,Robertson, K.M.,Coelho, M.M., Möller, L.M.}, issn = {SC/61/SM11}, year = {2009}, date = {2009-01-01}, journal = {Report to the Scientific Committee of the 61st meeting of the International Whaling Commisssion}, number = {7}, publisher = {International Whaling Commission}, abstract = {The genus Delphinus comprises two species and one subspecies: the short-beaked common dolphin, Delphinus delphis (Linnaeus, 1758), distributed in continental shelf and pelagic waters of the Atlantic and Pacific Oceans, the long-beaked common dolphin, D. capensis (Gray, 1828), distributed in nearshore tropical and temperate waters of the Pacific and Southern Atlantic Oceans, and the Arabian long-beaked common dolphin, D. capensis tropicalis van Bree, 1971, which occurs in the Indian Ocean. Here we present a worldwide phylogeographic study based on sequences of the mitochondrial DNA cytochrome b gene. A total of 279 individuals were analysed: 211 D. delphis from the Northeast (82) and Northwest (27) Atlantic, and Northeast (28) and Southwest (74) Pacific; 26 D. capensis from the Northeast Pacific, 18 D. capensis from the Southeast Atlantic, and 24 D. capensis tropicalis from the Indian Ocean. Haplotype and nucleotide diversities of most populations were high when compared with other cetacean species, which is possibly a signature of large, long-term effective population size. Shared haplotypes between the two common dolphin species and subspecies were found, as well as between all oceans sampled. Fixation indices (öST and FST) show that the tropicalis and D. capensis samples from the NE Pacific are differentiated from samples from all other regions. D. delphis from the Northeast and Southwest Pacific also show some differentiation from samples from other regions, but with relatively low values of fixation indices. In contrast, the median-joining network reveals clusters of haplotypes without a clear geographical or taxonomic correspondence. Overall, these results suggest that relatively high levels of gene flow occur between regions and possibly among recognized species, questioning current taxonomy, confounding population history and making the establishment of population boundaries very difficult. Several phylogeographical hypotheses for the observed patterns are currently being tested with recently developed methods that use coalescent models for estimating demographic parameters. Additionally, data on a powerful set of microsatellite markers are being obtained in order to document the direction and magnitude of events of recent gene flow between populations and oceanic regions.}, keywords = {Arabian Sea, Common dolphin, delphinus capensis, Delphinus delphis, delphinus sp., genetics, Indian Ocean, taxonomy}, pubstate = {published}, tppubtype = {techreport} } The genus Delphinus comprises two species and one subspecies: the short-beaked common dolphin, Delphinus delphis (Linnaeus, 1758), distributed in continental shelf and pelagic waters of the Atlantic and Pacific Oceans, the long-beaked common dolphin, D. capensis (Gray, 1828), distributed in nearshore tropical and temperate waters of the Pacific and Southern Atlantic Oceans, and the Arabian long-beaked common dolphin, D. capensis tropicalis van Bree, 1971, which occurs in the Indian Ocean. Here we present a worldwide phylogeographic study based on sequences of the mitochondrial DNA cytochrome b gene. A total of 279 individuals were analysed: 211 D. delphis from the Northeast (82) and Northwest (27) Atlantic, and Northeast (28) and Southwest (74) Pacific; 26 D. capensis from the Northeast Pacific, 18 D. capensis from the Southeast Atlantic, and 24 D. capensis tropicalis from the Indian Ocean. Haplotype and nucleotide diversities of most populations were high when compared with other cetacean species, which is possibly a signature of large, long-term effective population size. Shared haplotypes between the two common dolphin species and subspecies were found, as well as between all oceans sampled. Fixation indices (öST and FST) show that the tropicalis and D. capensis samples from the NE Pacific are differentiated from samples from all other regions. D. delphis from the Northeast and Southwest Pacific also show some differentiation from samples from other regions, but with relatively low values of fixation indices. In contrast, the median-joining network reveals clusters of haplotypes without a clear geographical or taxonomic correspondence. Overall, these results suggest that relatively high levels of gene flow occur between regions and possibly among recognized species, questioning current taxonomy, confounding population history and making the establishment of population boundaries very difficult. Several phylogeographical hypotheses for the observed patterns are currently being tested with recently developed methods that use coalescent models for estimating demographic parameters. Additionally, data on a powerful set of microsatellite markers are being obtained in order to document the direction and magnitude of events of recent gene flow between populations and oceanic regions. |