Global phylogeography with mixed-marker analysis reveals male-mediated dispersal in the endangered scalloped hammerhead shark (Sphyrna lewini)

• Published in: PloS one Vol. 7; no. 1; p. e29986
• Main Authors: Daly-Engel, Toby S, Seraphin, Kanesa D, Holland, Kim N, Coffey, John P, Nance, Holly A, Toonen, Robert J, Bowen, Brian W
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 10.01.2012; Public Library of Science (PLoS)
• Subjects: Analysis; Animal behavior; Animal Migration; Animals; Basins; Bays; Biogeography; Biology; Caretta caretta; Coastal ecology; Coastal environments; Dispersal; Dispersion; Endangered Species; Female; Females; Fish; Fisheries management; Gene flow; Genetic diversity; Genetic Loci - genetics; Genetic Markers; Genetic structure; Genetics, Population; Genotype; Habitats; Heterozygosity; Loci; Male; Males; Microsatellite Repeats - genetics; Microsatellites; Mitochondrial DNA; Ocean basins; Oceans; Parturition; Phylogeny; Phylogeography; Population structure; Sharks; Sharks - genetics; Sphyrna lewini; Wildlife conservation; South America; United States > US; Panama; Atlantic Ocean; Hawaii; Gulf of Mexico; Pacific Ocean; Florida
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0029986

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. 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. 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.