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Unidirectional trans-Atlantic gene flow and a mixed spawning area shape the genetic connectivity of Atlantic bluefin tuna
  • +18
  • Natalia Diaz-Arce,
  • Pierre-Alexandre Gagnaire,
  • David Richardson,
  • John Walter,
  • Sophie Arnaud-Haond,
  • Jean-Marc Fromentin,
  • Deirdre Brophy,
  • Molly Lutcavage,
  • Piero Addis,
  • Francisco Alemany,
  • Robert Allman,
  • Simeon Deguara,
  • Igaratza Fraile,
  • Nicolas Goñi,
  • Alex Hanke,
  • F. Saadet Karakulak,
  • Ashley Pacicco,
  • Joseph Quattro,
  • Jay Rooker,
  • Haritz Arrizabalaga,
  • Naiara Rodriguez-Ezpeleta
Natalia Diaz-Arce
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Pierre-Alexandre Gagnaire
Centre National de la receherche Scientifique (CNRS)
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David Richardson
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John Walter
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Sophie Arnaud-Haond
MARBEC
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Jean-Marc Fromentin
IFREMER
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Deirdre Brophy
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Molly Lutcavage
University of Massachusetts
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Piero Addis
Universita degli Studi di Cagliari
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Francisco Alemany
Instituto Español de Oceanografía
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Robert Allman
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Simeon Deguara
Federation of Maltese Aquaculture Producers
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Igaratza Fraile
AZTI-Tecnalia
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Nicolas Goñi
LUKE
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Alex Hanke
Fisheries and Oceans Canada
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F. Saadet Karakulak
Istanbul Universitesi
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Ashley Pacicco
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Joseph Quattro
University of South Carolina
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Jay Rooker
Texas A&M University
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Haritz Arrizabalaga
AZTI-Tecnalia
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Naiara Rodriguez-Ezpeleta
AZTI

Corresponding Author:nrodriguez@azti.es

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Abstract

The commercially important Atlantic bluefin tuna (Thunnus thynnus), a large migratory fish, has experienced notable recovery aided by accurate resource assessment and effective fisheries management efforts. Traditionally, this species has been perceived as consisting of eastern and western populations, spawning respectively in the Mediterranean Sea and the Gulf of Mexico, with mixing occurring throughout the Atlantic. However, recent studies have emerged challenging this assumption by revealing weak genetic differentiation and identifying a previously unknown spawning ground in the Slope Sea used by Atlantic bluefin tuna of uncertain origin. To further understand the current and past population structure and connectivity of Atlantic bluefin tuna, we have assembled a unique dataset including thousands of genome-wide Single Nucleotide Polymorphisms (SNPs) from five hundred larvae, young of the year and spawning adult samples covering the three spawning grounds and including individuals of other Thunnus species. Our analyses support two weakly differentiated but demographically connected ancestral populations that interbreed in the Slope Sea. Moreover, we also identified signatures of introgression from albacore into the Atlantic bluefin tuna genome, exhibiting varied frequencies across spawning areas, indicating strong gene flow from the Mediterranean Sea towards the Slope Sea. We hypothesize that the observed genetic differentiation may be attributed to increased gene flow caused by a recent intensification of westward migration by the eastern population, which could have implications for the genetic diversity and conservation of western populations. Future conservation efforts should consider these findings to address potential genetic homogenization in the species.
20 Jun 2023Submitted to Molecular Ecology
22 Jun 2023Submission Checks Completed
22 Jun 2023Assigned to Editor
22 Jun 2023Review(s) Completed, Editorial Evaluation Pending
02 Jul 2023Reviewer(s) Assigned
18 Aug 2023Editorial Decision: Revise Minor
02 Oct 20231st Revision Received
03 Oct 2023Submission Checks Completed
03 Oct 2023Assigned to Editor
03 Oct 2023Review(s) Completed, Editorial Evaluation Pending
19 Oct 2023Editorial Decision: Accept