Evidence of Fine‐Scale Genetic Structure in Tiger Sharks (Galeocerdo cuvier) Highlights the Importance of Stratified Sampling Regimes

ABSTRACT Understanding the biological connections between populations is essential to wildlife management and conservation. Genetic studies play a central role in characterizing these connections, but typically require stratified sampling regimes to assess the spatial extent and strength of gene flo...

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Main Authors: Jessica J. Fish, Christine Dudgeon, Adam Barnett, Paul A. Butcher, Bonnie J. Holmes, Charlie Huveneers, Lauren Meyer, Laurent Vigliola, Craig D. H. Sherman, Adam D. Miller
Format: Article
Language:English
Published: Wiley 2025-06-01
Series:Evolutionary Applications
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Online Access:https://doi.org/10.1111/eva.70117
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author Jessica J. Fish
Christine Dudgeon
Adam Barnett
Paul A. Butcher
Bonnie J. Holmes
Charlie Huveneers
Lauren Meyer
Laurent Vigliola
Craig D. H. Sherman
Adam D. Miller
author_facet Jessica J. Fish
Christine Dudgeon
Adam Barnett
Paul A. Butcher
Bonnie J. Holmes
Charlie Huveneers
Lauren Meyer
Laurent Vigliola
Craig D. H. Sherman
Adam D. Miller
author_sort Jessica J. Fish
collection DOAJ
description ABSTRACT Understanding the biological connections between populations is essential to wildlife management and conservation. Genetic studies play a central role in characterizing these connections, but typically require stratified sampling regimes to assess the spatial extent and strength of gene flow, and the relative influences of sex and ontogeny on patterns of connectivity. Yet, this can be challenging in some study systems, particularly in large marine species such as sharks, where genetic studies often rely on opportunistic and/or sampling conducted over large spatial scales. We demonstrate the importance of stratified sampling to identify previously undetected genetic structure in tiger sharks (Galeocerdo cuvier) off eastern Australia, where panmixia has been previously reported. We performed population genomic analyses on 414 tiger sharks, representing males and females and both juvenile‐subadult and adult‐life stages, and 21 locations spanning approximately 3000 km of eastern Australia and the Indo‐Pacific region. Similar to previous studies, we demonstrate a lack of overall genetic structure across the sampling area; however, our analysis shows evidence of spatial autocorrelation and local genetic structuring in juvenile‐subadult female tiger sharks. These results point to potential influences of sex and ontogeny on patterns of population genetic structure and connectivity in Australian tiger sharks. We discuss these findings in the context of essential habitats supporting tiger shark populations and risks of overstating the strength of biological connections among shark populations in the absence of appropriate sampling regimes.
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spelling doaj-art-110cb2a19cc04e80b19f44f039e229662025-08-20T03:30:01ZengWileyEvolutionary Applications1752-45712025-06-01186n/an/a10.1111/eva.70117Evidence of Fine‐Scale Genetic Structure in Tiger Sharks (Galeocerdo cuvier) Highlights the Importance of Stratified Sampling RegimesJessica J. Fish0Christine Dudgeon1Adam Barnett2Paul A. Butcher3Bonnie J. Holmes4Charlie Huveneers5Lauren Meyer6Laurent Vigliola7Craig D. H. Sherman8Adam D. Miller9School of Life and Environmental Sciences Deakin University Warrnambool Victoria AustraliaSchool of Science, Technology & Engineering University of the Sunshine Coast Petrie Queensland AustraliaBiopixel Oceans Foundation Cairns Queensland AustraliaSchool of Life and Environmental Sciences Deakin University Warrnambool Victoria AustraliaSchool of Science, Technology & Engineering University of the Sunshine Coast Sippy Downs Queensland AustraliaFlinders University, College of Science and Engineering Adelaide South Australia AustraliaFlinders University, College of Science and Engineering Adelaide South Australia AustraliaENTROPIE, SANTECO, Institut de Recherche Pour le Développement Noumea New Caledonia FranceSchool of Life and Environmental Sciences Deakin University Warrnambool Victoria AustraliaFlinders University, College of Science and Engineering Adelaide South Australia AustraliaABSTRACT Understanding the biological connections between populations is essential to wildlife management and conservation. Genetic studies play a central role in characterizing these connections, but typically require stratified sampling regimes to assess the spatial extent and strength of gene flow, and the relative influences of sex and ontogeny on patterns of connectivity. Yet, this can be challenging in some study systems, particularly in large marine species such as sharks, where genetic studies often rely on opportunistic and/or sampling conducted over large spatial scales. We demonstrate the importance of stratified sampling to identify previously undetected genetic structure in tiger sharks (Galeocerdo cuvier) off eastern Australia, where panmixia has been previously reported. We performed population genomic analyses on 414 tiger sharks, representing males and females and both juvenile‐subadult and adult‐life stages, and 21 locations spanning approximately 3000 km of eastern Australia and the Indo‐Pacific region. Similar to previous studies, we demonstrate a lack of overall genetic structure across the sampling area; however, our analysis shows evidence of spatial autocorrelation and local genetic structuring in juvenile‐subadult female tiger sharks. These results point to potential influences of sex and ontogeny on patterns of population genetic structure and connectivity in Australian tiger sharks. We discuss these findings in the context of essential habitats supporting tiger shark populations and risks of overstating the strength of biological connections among shark populations in the absence of appropriate sampling regimes.https://doi.org/10.1111/eva.70117eastern Australiaelasmobranchlocal genetic structureontogenypopulation genomicssex
spellingShingle Jessica J. Fish
Christine Dudgeon
Adam Barnett
Paul A. Butcher
Bonnie J. Holmes
Charlie Huveneers
Lauren Meyer
Laurent Vigliola
Craig D. H. Sherman
Adam D. Miller
Evidence of Fine‐Scale Genetic Structure in Tiger Sharks (Galeocerdo cuvier) Highlights the Importance of Stratified Sampling Regimes
Evolutionary Applications
eastern Australia
elasmobranch
local genetic structure
ontogeny
population genomics
sex
title Evidence of Fine‐Scale Genetic Structure in Tiger Sharks (Galeocerdo cuvier) Highlights the Importance of Stratified Sampling Regimes
title_full Evidence of Fine‐Scale Genetic Structure in Tiger Sharks (Galeocerdo cuvier) Highlights the Importance of Stratified Sampling Regimes
title_fullStr Evidence of Fine‐Scale Genetic Structure in Tiger Sharks (Galeocerdo cuvier) Highlights the Importance of Stratified Sampling Regimes
title_full_unstemmed Evidence of Fine‐Scale Genetic Structure in Tiger Sharks (Galeocerdo cuvier) Highlights the Importance of Stratified Sampling Regimes
title_short Evidence of Fine‐Scale Genetic Structure in Tiger Sharks (Galeocerdo cuvier) Highlights the Importance of Stratified Sampling Regimes
title_sort evidence of fine scale genetic structure in tiger sharks galeocerdo cuvier highlights the importance of stratified sampling regimes
topic eastern Australia
elasmobranch
local genetic structure
ontogeny
population genomics
sex
url https://doi.org/10.1111/eva.70117
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