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Global population genetic dynamics of a highly migratory, apex predator shark
Author(s) -
Bernard Andrea M.,
Feldheim Kevin A.,
Heithaus Michael R.,
Wintner Sabine P.,
Wetherbee Bradley M.,
Shivji Mahmood S.
Publication year - 2016
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1111/mec.13845
Subject(s) - biology , apex predator , biological dispersal , genetic structure , population , phylogeography , ecology , generalist and specialist species , isolation by distance , pelagic zone , fishery , genetic variation , predation , habitat , phylogenetics , biochemistry , demography , sociology , gene
Knowledge of genetic connectivity dynamics in the world's large‐bodied, highly migratory, apex predator sharks across their global ranges is limited. One such species, the tiger shark ( Galeocerdo cuvier ), occurs worldwide in warm temperate and tropical waters, uses remarkably diverse habitats (nearshore to pelagic) and possesses a generalist diet that can structure marine ecosystems through top‐down processes. We investigated the phylogeography and the global population structure of this exploited, phylogenetically enigmatic shark by using 10 nuclear microsatellites ( n = 380) and sequences from the mitochondrial control region ( CR , n = 340) and cytochrome oxidase I gene ( n = 100). All three marker classes showed the genetic differentiation between tiger sharks from the western Atlantic and Indo‐Pacific ocean basins (microsatellite F ST > 0.129; CR Φ ST > 0.497), the presence of North vs. southwestern Atlantic differentiation and the isolation of tiger sharks sampled from Hawaii from other surveyed locations. Furthermore, mitochondrial DNA revealed high levels of intraocean basin matrilineal population structure, suggesting female philopatry and sex‐biased gene flow. Coalescent‐ and genetic distance‐based estimates of divergence from CR sequences were largely congruent ( d corr = 0.0015–0.0050), indicating a separation of Indo‐Pacific and western Atlantic tiger sharks <1 million years ago. Mitochondrial haplotype relationships suggested that the western South Atlantic Ocean was likely a historical connection for interocean basin linkages via the dispersal around South Africa. Together, the results reveal unexpectedly high levels of population structure in a highly migratory, behaviourally generalist, cosmopolitan ocean predator, calling for management and conservation on smaller‐than‐anticipated spatial scales.