title: Genetic diversity and population structure of the pelagic thresher shark (Alopias pelagicus) in the Pacific Ocean: evidence for two evolutionarily significant units.
abstract: There has been an increasing concern about shark overexploitation in the last decade, especially for open ocean shark species, where there is a paucity of data about their life histories and population dynamics. Little is known regarding the population structure of the pelagic thresher shark, Alopias pelagicus. Though an earlier study using mtDNA control region data, showed evidence for differences between eastern and western Pacific populations, the study was hampered by low sample size and sparse geographic coverage, particularly a lack of samples from the central Pacific. Here, we present the population structure of Alopias pelagicus analyzing 351 samples from six different locations across the Pacific Ocean. Using data from mitochondrial DNA COI sequences and seven microsatellite loci we found evidence of strong population differentiation between western and eastern Pacific populations and evidence for reciprocally monophyly for organelle haplotypes and significant divergence of allele frequencies at nuclear loci, suggesting the existence of two Evolutionarily Significant Units (ESU) in the Pacific Ocean. Interestingly, the population in Hawaii appears to be composed of both ESUs in what seems to be clear sympatry with reproductive isolation. These results may indicate the existence of a new cryptic species in the Pacific Ocean. The presence of these distinct ESUs highlights the need for revised management plans for this highly exploited shark throughout its range.
authors.affiliation: Laboratorio de Ecología Molecular de Vertebrados Acuáticos-LEMVA, Departamento de Ciencias Biológicas, Universidad de Los Andes, Bogotá, Colombia.
authors.forename: Diego
authors.initials: D
authors.lastname: Cardeñosa
authors.affiliation: Southwest Fisheries Science Center, National Marine Fisheries Service, La Jolla, California, United States of America.
authors.forename: John
authors.initials: J
authors.lastname: Hyde
authors.affiliation: Laboratorio de Ecología Molecular de Vertebrados Acuáticos-LEMVA, Departamento de Ciencias Biológicas, Universidad de Los Andes, Bogotá, Colombia.
authors.forename: Susana
authors.initials: S
authors.lastname: Caballero
mesh_terms: D000483:Alleles; D025041:Animal Migration; D000818:Animals; D001483:Base Sequence; D004272:DNA, Mitochondrial / Q000235:genetics*; D003576:Electron Transport Complex IV / Q000235:genetics*; D005787:Gene Frequency; D014644:Genetic Variation; D005828:Genetics, Population; D006239:Haplotypes; D006254:Hawaii; D018895:Microsatellite Repeats; D008969:Molecular Sequence Data; D010140:Pacific Ocean; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D012754:Sharks / Q000145:classification / Q000235:genetics*; D061350:Sympatry
chemical_list: D004272:DNA, Mitochondrial; D003576:Electron Transport Complex IV