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Auteur (up) Bailleul, D.; Mackenzie, A.; Sacchi, O.; Poisson, F.; Bierne, N.; Arnaud‐Haond, S.
Titre Large-scale genetic panmixia in the blue shark (Prionace glauca): A single worldwide population, or a genetic lag-time effect of the “grey zone” of differentiation? Type Article scientifique
Année 2018 Publication Revue Abrégée Evolutionary Applications
Volume 11 Numéro 5 Pages 614-630
Mots-Clés blue shark; conservation; fisheries; genetic panmixia; Prionace glauca; stock
Résumé The blue shark Prionace glauca, among the most common and widely studied pelagic sharks, is a top predator, exhibiting the widest distribution range. However, little is known about its population structure and spatial dynamics. With an estimated removal of 10–20 million individuals per year by fisheries, the species is classified as “Near Threatened” by International Union for Conservation of Nature. We lack the knowledge to forecast the long-term consequences of such a huge removal on this top predator itself and on its trophic network. The genetic analysis of more than 200 samples collected at broad scale (from Mediterranean Sea, North Atlantic and Pacific Oceans) using mtDNA and nine microsatellite markers allowed to detect signatures of genetic bottlenecks but a nearly complete genetic homogeneity across the entire studied range. This apparent panmixia could be explained by a genetic lag-time effect illustrated by simulations of demographic changes that were not detectable through standard genetic analysis before a long transitional phase here introduced as the “population grey zone.” The results presented here can thus encompass distinct explanatory scenarios spanning from a single demographic population to several independent populations. This limitation prevents the genetic-based delineation of stocks and thus the ability to anticipate the consequences of severe depletions at all scales. More information is required for the conservation of population(s) and management of stocks, which may be provided by large-scale sampling not only of individuals worldwide, but also of loci genomewide.
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2353
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Auteur (up) Delrieu‐Trottin, E.; Durand, J.-D.; Limmon, G.; Sukmono, T.; Kadarusman; Sugeha, H.Y.; Chen, W.-J.; Busson, F.; Borsa, P.; Dahruddin, H.; Sauri, S.; Fitriana, Y.; Zein, M.S.A.; Hocdé, R.; Pouyaud, L.; Keith, P.; Wowor, D.; Steinke, D.; Hanner, R.; Hubert, N.
Titre Biodiversity inventory of the grey mullets (Actinopterygii: Mugilidae) of the Indo-Australian Archipelago through the iterative use of DNA-based species delimitation and specimen assignment methods Type Article scientifique
Année 2020 Publication Revue Abrégée Evolutionary Applications
Volume Numéro Pages
Mots-Clés Coral Triangle; cryptic diversity; DNA barcoding; reference library; taxonomic gap
Résumé DNA barcoding opens new perspectives on the way we document biodiversity. Initially proposed to circumvent the limits of morphological characters to assign unknown individuals to known species, DNA barcoding has been used in a wide array of studies where collecting species identity constitutes a crucial step. The assignment of unknowns to knowns assumes that species are already well identified and delineated, making the assignment performed reliable. Here, we used DNA-based species delimitation and specimen assignment methods iteratively to tackle the inventory of the Indo-Australian Archipelago grey mullets, a notorious case of taxonomic complexity that requires DNA-based identification methods considering that traditional morphological identifications are usually not repeatable and sequence mislabeling is common in international sequence repositories. We first revisited a DNA barcode reference library available at the global scale for Mugilidae through different DNA-based species delimitation methods to produce a robust consensus scheme of species delineation. We then used this curated library to assign unknown specimens collected throughout the Indo-Australian Archipelago to known species. A second iteration of OTU delimitation and specimen assignment was then performed. We show the benefits of using species delimitation and specimen assignment methods iteratively to improve the accuracy of specimen identification and propose a workflow to do so.
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2729
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Auteur (up) GAGNAIRE, P.-A.; BROQUET, T.; AURELLE, D.; VIARD, F.; SOUISSI, A.; BONHOMME, F.; ARNAUD-HAOND, S.; Bierne, N.
Titre Using neutral, selected, and hitchhiker loci to assess connectivity of marine populations in the genomic era Type Article scientifique
Année 2015 Publication Revue Abrégée Evolutionary Applications
Volume 8 Numéro 8 Pages 769-786
Mots-Clés connectivity; gene flow; marine conservation; population genomics; Population structure
Résumé Estimating the rate of exchange of individuals among populations is a central concern to evolutionary ecology and its applications to conservation and management. For instance, the efficiency of protected areas in sustaining locally endangered populations and ecosystems depends on reserve network connectivity. The population genetics theory offers a powerful framework for estimating dispersal distances and migration rates from molecular data. In the marine realm, however, decades of molecular studies have met limited success in inferring genetic connectivity, due to the frequent lack of spatial genetic structure in species exhibiting high fecundity and dispersal capabilities. This is especially true within biogeographic regions bounded by well-known hotspots of genetic differentiation. Here, we provide an overview of the current methods for estimating genetic connectivity using molecular markers and propose several directions for improving existing approaches using large population genomic datasets. We highlight several issues that limit the effectiveness of methods based on neutral markers when there is virtually no genetic differentiation among samples. We then focus on alternative methods based on markers influenced by selection. Although some of these methodologies are still underexplored, our aim was to stimulate new research to test how broadly they are applicable to nonmodel marine species. We argue that the increased ability to apply the concepts of cline analyses will improve dispersal inferences across physical and ecological barriers that reduce connectivity locally. We finally present how neutral markers hitchhiking with selected loci can also provide information about connectivity patterns within apparently well-mixed biogeographic regions. We contend that one of the most promising applications of population genomics is the use of outlier loci to delineate relevant conservation units and related eco-geographic features across which connectivity can be measured.
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1434
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