Global Phylogeography with Mixed-Marker Analysis Reveals Male-Mediated Dispersal in the Endangered Scalloped Hammerhead Shark (Sphyrna lewini)

Abstract

BackgroundThe 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 ΦST = 0.749) and significant population separations across oceans and between discontinuous continental coastlines.Methodology/Principal FindingsWe 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 (ΦST = 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/SignificanceThese 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.

Equatorial dispersal barriers and limited population connectivity among oceans in a planktonic copepod

“…Multiple processes could explain this pattern (Goetze 2005). This absence of genetic structure may occur due to contemporary migration between Atlantic and Indian Ocean populations, as has been reported for some fishes and sharks (Brendtro et al 2008;Daly-Engel et al 2012). An alternative hypothesis is that these populations experienced migration historically, and a barrier to dispersal has arisen only recently between these ocean basins.…”

Genetic bottlenecks in Pristis sawfishes in northern Australian waters

“…Assemblages of each of P. clavata, P. zijsron, and P. pristis on the west coast and the Gulf of Carpentaria appear to have moderate to high levels of genetic diversity at microsatellite loci that are within the ranges reported for other elasmobranchs, including sawfish (Chapman et al 2011, Daly-Engel et al 2012, O'Leary et al 2015, with no apparent spatial pattern in genetic diversity. These results are in contrast to the moderate to low levels of genetic diversity found in the mtDNA control region for each species (Phillips et al 2011).…”

A dated molecular phylogeny of manta and devil rays (Mobulidae) based on mitogenome and nuclear sequences

“…4) is consistent with the closing of the Isthmus of Panama, which most likely took place between 3.1 and 2.8 Mya (Coates et al, 2003;Coates and Obando, 1996). This event created a permanent separation between East Pacific and Atlantic mobulids as is the case for many marine species (Lessios, 2008) including various elasmobranchs (Daly-Engel et al, 2012;Keeney and Heist, 2006;Schultz et al, 2008;Stelbrink et al, 2010).…”