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From rivers to ocean basins: the role of ocean barriers and philopatry in the genetic structuring of a cosmopolitan coastal predator
  • +34
  • Floriaan Devloo-Delva,
  • Christopher Burridge,
  • Peter Kyne,
  • Juerg Brunnschweiler,
  • Demian Chapman,
  • Patricia Charvet,
  • Xiao Chen,
  • Geremy Cliff,
  • Ryan Daly,
  • Marcus Drymon,
  • Mario Espinoza,
  • Daniel Fernando,
  • Laura Garcia Barcia,
  • Kerstin Glaus,
  • Blanca Gonzalez-Garza,
  • Michael Grant,
  • Rasanthi Gunasekera,
  • Sebastian Hernandez,
  • Susumu Hyodo,
  • Rima Jabado,
  • Sebastien Jaquemet,
  • Grant Johnson,
  • James Ketchum,
  • Hélène Magalon,
  • James Marthick,
  • Frederik Mollen,
  • Stefano Mona,
  • Gavin Naylor,
  • John Nevill,
  • Nicole Phillips,
  • Richard Pillans,
  • Bautisse Postaire,
  • Amy Smoothey,
  • Katsunori Tachihara,
  • Bree Tillett,
  • Jorge Valerio-Vargas,
  • Pierre Feutry
Floriaan Devloo-Delva
Commonwealth Scientific and Industrial Research Organisation

Corresponding Author:floriaan.devloo-delva@csiro.au

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Christopher Burridge
University of Tasmania
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Peter Kyne
Charles Darwin University
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Juerg Brunnschweiler
Independent Researcher
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Demian Chapman
Florida International University Biscayne Bay Campus
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Patricia Charvet
Universidade Federal do Ceará
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Xiao Chen
South China Agricultural University
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Geremy Cliff
KwaZulu-Natal Sharks Board Maritime Centre of Excellence
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Ryan Daly
South African Association for Marine Biological Research
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Marcus Drymon
Mississippi State University
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Mario Espinoza
Universidad de Costa Rica
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Daniel Fernando
Blue Resources Trust
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Laura Garcia Barcia
Florida International University
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Kerstin Glaus
The University of the South Pacific
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Blanca Gonzalez-Garza
Pelagios-Kakunja
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Michael Grant
James Cook University
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Rasanthi Gunasekera
Commonwealth Scientific and Industrial Research Organisation
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Sebastian Hernandez
Universidad VERITAS
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Susumu Hyodo
The University of Tokyo
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Rima Jabado
Elasmo Project
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Sebastien Jaquemet
Université de la Réunion
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Grant Johnson
Northern Territory Government
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James Ketchum
MigraMar
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Hélène Magalon
Université de la Réunion
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James Marthick
University of Tasmania
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Frederik Mollen
Elasmobranch Research
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Stefano Mona
Muséum National d'Histoire Naturelle
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Gavin Naylor
University of Florida
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John Nevill
Environment Seychelles
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Nicole Phillips
University of Southern Mississippi
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Richard Pillans
Commonwealth Scientific and Industrial Research Organisation
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Bautisse Postaire
Université de la Réunion
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Amy Smoothey
New South Wales Government
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Katsunori Tachihara
University of the Ryukyus
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Bree Tillett
The University of Queensland Diamantina Institute
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Jorge Valerio-Vargas
Universidad de Costa Rica
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Pierre Feutry
Commonwealth Scientific and Industrial Research Organisation
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Abstract

Understanding the population structure of a species is important to accurately assess its conservation status and manage the risk of local extinction. The Bull Shark (Carcharhinus leucas) faces varying levels of exploitation around the world due to its coastal distribution. Information regarding population connectivity is crucial to evaluate its conservation status and local fishing impacts. In this study, we sampled 922 putative Bull Sharks from 19 locations in the first global assessment of population structure of this cosmopolitan species. Using a recently developed DNA-capture approach (DArTcap), samples were genotyped for 3,400 nuclear markers. Additionally, full mitochondrial genomes of 384 Indo-Pacific samples were sequenced. Reproductive isolation was found between and across ocean basins (eastern Pacific, western Atlantic, eastern Atlantic, Indo-West Pacific) with distinct island populations in Japan and Fiji. Bull Sharks appear to maintain reproductive connectivity using shallow coastal waters as dispersal corridors, whereas large oceanic distances and historical land-bridges act as barriers. Females tend to return to the same area for reproduction, making them more susceptible to local threats and an important focus for management actions. Given these behaviours, the exploitation of Bull Sharks from insular populations, such as Japan and Fiji, may instigate local decline that cannot readily be replenished by immigration, which can in turn affect ecosystem dynamics and functions. These data also supported the development of a genetic panel to ascertain the population of origin, which will be useful in monitoring the trade of fisheries products and assessing population-level impacts of this harvest.