Whole‐Genome Resequencing Reveals Exceptions to Panmixia in the Exploited Top Fish Predator Antarctic Toothfish ( Dissostichus mawsoni )
7 affiliations
- 1Berlin Center for Genomics in Biodiversity Research, BeGenDiv Berlin Germany
- 2Department of Evolutionary Genetics Leibniz‐Institut für Zoo‐ und Wildtierforschung, IZW Berlin Germany
- 3Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA‐CNRS‐UVSQ, Université Paris‐Saclay Gif‐sur‐Yvette France
- 4Laboratoire d'Océanographie et du Climat Expérimentations et Approches Numériques, LOCEAN/IPSL, UPMC‐CNRS‐IRD‐MNHN, Sorbonne Université Paris France
- 5Institute of Biochemistry and Biology, Evolutionary Biology & Systematic Zoology University of Potsdam Potsdam Germany
- 6Department of Integrative Biology University of South Florida Tampa Florida USA
- 7Leibniz‐Institut für Gewässerökologie und Binnenfischerei (IGB) Berlin Germany
Abstract
Antarctic toothfish (Dissostichus mawsoni) are a critical top fish predator in the Southern Ocean whose population dynamics are strongly influenced by a changing climate and fishing pressure. Their complex, long-lived life history presents challenges to understanding their population dynamics that we endeavor to overcome through the use of both reduced-representation sequencing and whole-genome resequencing data from fish across different cohorts. Our unique sample set allowed us to compare genomic structure, diversity, and demographic changes between cohorts born before and after the year 2000, when changes to fisheries management practices in the Southern Ocean reduced incidences of illegal, unreported, and unregulated fishing. While our population structure analyses corroborate recent studies showing panmixia across circumpolar populations of D. mawsoni, comparisons between cohorts revealed key exceptions. A lack of admixture in fish born before 2000 contrasted with widespread admixture among post-2000 individuals, consistent with increased mixing and/or genotype influx. Notably, genome-wide diversity declined over time in the Ross Sea (management area 88), with significant losses observed in heterozygosity between pre-2000 and post-2000 cohorts. Elevated levels of inbreeding in the Ross Sea, coupled with evidence for recent population contraction from positive Tajima's D values, provided potential explanations for the observed reductions in genomic diversity. Our results reconcile circumpolar panmixia with localized erosion of diversity and elevated inbreeding in the Ross Sea sector, underscoring the value of temporal monitoring and the need to prioritize future research on the interplay between fisheries pressure and environmental change in driving population dynamics and genomic structure in exploited Southern Ocean species like toothfish.
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BibTeX
@article{caccavo2026wholegenome,
title = {{Whole‐Genome Resequencing Reveals Exceptions to Panmixia in the Exploited Top Fish Predator Antarctic Toothfish ( Dissostichus mawsoni )}},
author = {Jilda Alicia Caccavo and Larissa S. Arantes and Enrique Celemín and Susan Mbedi and Sarah Sparmann and Camila J. Mazzoni},
journal = {Ecology and Evolution},
year = {2026},
month = oct,
doi = {10.1002/ece3.74262},
url = {https://hal.science/hal-05838851v1},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Whole‐Genome Resequencing Reveals Exceptions to Panmixia in the Exploited Top Fish Predator Antarctic Toothfish ( Dissostichus mawsoni )
AU - Jilda Alicia Caccavo
AU - Larissa S. Arantes
AU - Enrique Celemín
AU - Susan Mbedi
AU - Sarah Sparmann
AU - Camila J. Mazzoni
PY - 2026
DA - 2026/10/19
JO - Ecology and Evolution
DO - 10.1002/ece3.74262
UR - https://hal.science/hal-05838851v1
AB - Antarctic toothfish (Dissostichus mawsoni) are a critical top fish predator in the Southern Ocean whose population dynamics are strongly influenced by a changing climate and fishing pressure. Their complex, long-lived life history presents challenges to understanding their population dynamics that we endeavor to overcome through the use of both reduced-representation sequencing and whole-genome resequencing data from fish across different cohorts. Our unique sample set allowed us to compare genomic structure, diversity, and demographic changes between cohorts born before and after the year 2000, when changes to fisheries management practices in the Southern Ocean reduced incidences of illegal, unreported, and unregulated fishing. While our population structure analyses corroborate recent studies showing panmixia across circumpolar populations of D. mawsoni, comparisons between cohorts revealed key exceptions. A lack of admixture in fish born before 2000 contrasted with widespread admixture among post-2000 individuals, consistent with increased mixing and/or genotype influx. Notably, genome-wide diversity declined over time in the Ross Sea (management area 88), with significant losses observed in heterozygosity between pre-2000 and post-2000 cohorts. Elevated levels of inbreeding in the Ross Sea, coupled with evidence for recent population contraction from positive Tajima's D values, provided potential explanations for the observed reductions in genomic diversity. Our results reconcile circumpolar panmixia with localized erosion of diversity and elevated inbreeding in the Ross Sea sector, underscoring the value of temporal monitoring and the need to prioritize future research on the interplay between fisheries pressure and environmental change in driving population dynamics and genomic structure in exploited Southern Ocean species like toothfish.
SN - 2045-7758
ER -