title: Global phylogeography with mixed-marker analysis reveals male-mediated dispersal in the endangered scalloped hammerhead shark (Sphyrna lewini).
abstract: BACKGROUND
  The scalloped hammerhead shark, Sphyrna lewini, is a large endangered predator with a circumglobal distribution, observed in the open ocean but linked ontogenetically to coastal embayments for parturition and juvenile development. A previous survey of maternal (mtDNA) markers demonstrated strong genetic partitioning overall (global Φ(ST) = 0.749) and significant population separations across oceans and between discontinuous continental coastlines.
  
  
  RESULTS
  We surveyed the same global range with increased sample coverage (N = 403) and 13 microsatellite loci to assess the male contribution to dispersal and population structure. Biparentally inherited microsatellites reveal low or absent genetic structure across ocean basins and global genetic differentiation (F(ST) = 0.035) over an order of magnitude lower than the corresponding measures for maternal mtDNA lineages (Φ(ST) = 0.749). Nuclear allelic richness and heterozygosity are high throughout the Indo-Pacific, while genetic structure is low. In contrast, allelic diversity is low while population structure is higher for populations at the ends of the range in the West Atlantic and East Pacific.
  
  
  CONCLUSIONS
  These data are consistent with the proposed Indo-Pacific center of origin for S. lewini, and indicate that females are philopatric or adhere to coastal habitats while males facilitate gene flow across oceanic expanses. This study includes the largest sampling effort and the most molecular loci ever used to survey the complete range of a large oceanic predator, and findings emphasize the importance of incorporating mixed-marker analysis into stock assessments of threatened and endangered shark species.
authors.affiliation: Department of Zoology, University of Hawaii at Mānoa, Honolulu, Hawaii, United States of America. tengel@email.arizona.edu
authors.forename: Toby S
authors.initials: TS
authors.lastname: Daly-Engel
authors.forename: Kanesa D
authors.initials: KD
authors.lastname: Seraphin
authors.forename: Kim N
authors.initials: KN
authors.lastname: Holland
authors.forename: John P
authors.initials: JP
authors.lastname: Coffey
authors.forename: Holly A
authors.initials: HA
authors.lastname: Nance
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Toonen
authors.forename: Brian W
authors.initials: BW
authors.lastname: Bowen
mesh_terms: D025041:Animal Migration; D000818:Animals; D056727:Endangered Species; D005260:Female; D056426:Genetic Loci / Q000235:genetics; D005819:Genetic Markers; D005828:Genetics, Population; D005838:Genotype; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics; D010802:Phylogeny; D058974:Phylogeography; D012754:Sharks / Q000235:genetics*
chemical_list: D005819:Genetic Markers