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Auteur Rey, C.; Darnaude, A.; Ferraton, F.; Guinand, B.; Bonhomme, F.; Bierne, N.; Gagnaire, P.-A.
Titre Within-Generation Polygenic Selection Shapes Fitness-Related Traits across Environments in Juvenile Sea Bream Type Article scientifique
Année (down) 2020 Publication Revue Abrégée Genes
Volume 11 Numéro 4 Pages 398
Mots-Clés antagonistic pleiotropy; fitness trade-off; habitat association; juvenile growth; polygenic scores; RAD-sequencing; spatially varying selection
Résumé Understanding the genetic underpinnings of fitness trade-offs across spatially variable environments remains a major challenge in evolutionary biology. In Mediterranean gilthead sea bream, first-year juveniles use various marine and brackish lagoon nursery habitats characterized by a trade-off between food availability and environmental disturbance. Phenotypic differences among juveniles foraging in different habitats rapidly appear after larval settlement, but the relative role of local selection and plasticity in phenotypic variation remains unclear. Here, we combine phenotypic and genetic data to address this question. We first report correlations of opposite signs between growth and condition depending on juvenile habitat type. Then, we use single nucleotide polymorphism (SNP) data obtained by Restriction Associated DNA (RAD) sequencing to search for allele frequency changes caused by a single generation of spatially varying selection between habitats. We found evidence for moderate selection operating at multiple loci showing subtle allele frequency shifts between groups of marine and brackish juveniles. We identified subsets of candidate outlier SNPs that, in interaction with habitat type, additively explain up to 3.8% of the variance in juvenile growth and 8.7% in juvenile condition; these SNPs also explained significant fraction of growth rate in an independent larval sample. Our results indicate that selective mortality across environments during early-life stages involves complex trade-offs between alternative growth strategies.
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2784
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Auteur Boulanger, E.; Dalongeville, A.; Andrello, M.; Mouillot, D.; Manel, S.
Titre Spatial graphs highlight how multi-generational dispersal shapes landscape genetic patterns Type Article scientifique
Année (down) 2020 Publication Revue Abrégée Ecography
Volume Numéro Pages
Mots-Clés connectivity; fish populations; flow; genetic connectivity; habitat; Mediterranean Sea; migration rates; models; Mullus surmuletus; mullus-surmuletus; ocean currents; r-package; seascape genetics; spatial graphs; stepping-stone dispersal; unsampled populations
Résumé Current approaches that compare spatial genetic structure of a given species and the dispersal of its mobile phase can detect a mismatch between both patterns mainly due to processes acting at different temporal scales. Genetic structure result from gene flow and other evolutionary and demographic processes over many generations, while dispersal predicted from the mobile phase often represents solely one generation on a single time-step. In this study, we present a spatial graph approach to landscape genetics that extends connectivity networks with a stepping-stone model to represent dispersal between suitable habitat patches over multiple generations. We illustrate the approach with the case of the striped red mullet Mullus surmuletus in the Mediterranean Sea. The genetic connectivity of M. surmuletus was not correlate with the estimated dispersal probability over one generation, but with the stepping-stone estimate of larval dispersal, revealing the temporal scale of connectivity across the Mediterranean Sea. Our results highlight the importance of considering multiple generations and different time scales when relating demographic and genetic connectivity. The spatial graph of genetic distances further untangles intra-population genetic structure revealing the Siculo-Tunisian Strait as an important corridor rather than a barrier for gene flow between the Western- and Eastern Mediterranean basins, and identifying Mediterranean islands as important stepping-stones for gene flow between continental populations. Our approach can be easily extended to other systems and environments.
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ISSN 0906-7590 ISBN Médium
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Notes WOS:000533549700001 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2789
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Auteur Mannocci, L.; Roberts, J.J.; Pedersen, E.J.; Halpin, P.N.
Titre Geographical differences in habitat relationships of cetaceans across an ocean basin Type Article scientifique
Année (down) 2020 Publication Revue Abrégée Ecography
Volume Numéro Pages
Mots-Clés associations; atlantic; conservation; distribution models; diversity; environmental predictors; geographical variation; habitat relationships; highly mobile marine species; marine mammals; North Atlantic Ocean; populations; predator; species distribution modeling; temperature; whales
Résumé The distributions of highly mobile marine species such as cetaceans are increasingly modeled at basin scale by combining data from multiple regions. However, these basin-wide models often overlook geographical variations in species habitat relationships between regions. We tested for geographical variations in habitat relationships for a suite of cetacean taxa between the two sides of the North Atlantic basin. Using cetacean visual survey data and remote sensing data from the western and eastern basin in summer, we related the probability of presence of twelve cetacean taxa from three guilds to seafloor depth, sea surface temperature and primary productivity. In a generalized additive model framework, we fitted 1) basin-wide (BW) models, assuming a single global relationship, 2) region-specific intercepts (RI) models, assuming relationships with the same shape in both regions, but allowing a region-specific intercept and 3) region-specific shape (RS) models, assuming relationships with different shapes between regions. RS models mostly yielded significantly better fits than BW models, indicating cetacean occurrences were better modeled with region-specific than with global relationships. The better fits of RS models over RI models further provided statistical evidence for differences in the shapes of region-specific relationships. Baleen whales showed striking differences in both the shapes of relationships and their mean presence probabilities between regions. Deep diving whales and delphinoids showed contrasting relationships between regions with few exceptions (e.g. non-statistically different shapes of region-specific relationships for harbor porpoise and beaked whales with depth). Our findings stress the need to account for geographical differences in habitat relationships between regions when modeling species distributions from combined data at the basin scale. Our proposed hypotheses offer a roadmap for understanding why habitat relationships may geographically vary in cetaceans and other highly mobile marine species.
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Langue English Langue du Résumé Titre Original
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Volume de collection Numéro de collection Edition
ISSN 0906-7590 ISBN Médium
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Notes WOS:000531110000001 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2792
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Auteur Marre, G.; Deter, J.; Holon, F.; Boissery, P.; Luque, S.
Titre Fine-scale automatic mapping of living Posidonia oceanica seagrass beds with underwater photogrammetry Type Article scientifique
Année (down) 2020 Publication Revue Abrégée Marine Ecology Progress Series
Volume 643 Numéro Pages 63-74
Mots-Clés Benthic habitat mapping; Monitoring; Posidonia oceanica; Reconstruction uncertainty; Submerged aquatic vegetation; Underwater photogrammetry
Résumé The Mediterranean seagrass Posidonia oceanica, which provides highly valuable ecosystem services, is subject to increasing anthropogenic pressures, causing habitat loss or fragmentation. Whilst airborne images and acoustic data can be used for monitoring seagrass coverage at a macro-scale and over long time periods, monitoring its health in the short term requires precision mapping in order to assess current regression/progression of individual meadows. However, current fine-scale underwater techniques in the field are imprecise and time-demanding. We propose an automatic classification approach based on underwater photogrammetry for an operational, cost- and time-effective fine-scale monitoring method. The method uses a property of the sparse cloud generated during bundle adjustment—the reconstruction uncertainty—to map seagrass patches. The mean precision, recall and F1 score of the method over 21 study sites with different morphologies were 0.79, 0.91 and 0.84, respectively. However, the fragmentation level of the meadows had a significant negative effect on classification performances. The temporal monitoring of 3 sites using this method proved its operability and showed a positive evolution index of the corresponding meadows over a period of 3 yr. This method is generalizable for most encountered configurations and can be integrated in a large monitoring system, as it enables the production of numerous seagrass maps over a short period of time. Moreover, our methodology could be generalized and applied in the study of other submerged aquatic vegetation by adjusting the method’s parameters.
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ISSN 0171-8630, 1616-1599 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2801
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Auteur van der Geest, M.; van der Lely, J.A.C.; van Gils, J.A.; Piersma, T.; Lok, T.
Titre Density-dependent growth of bivalves dominating the intertidal zone of Banc d'Arguin, Mauritania: importance of feeding mode, habitat and season Type Article scientifique
Année (down) 2019 Publication Revue Abrégée Mar. Ecol.-Prog. Ser.
Volume 610 Numéro Pages 51-63
Mots-Clés biomass; Carrying capacity; Chemosymbiosis; competition; Density dependence; dynamics; ecosystem; Environmental heterogeneity; Feeding guild; flats; populations; seagrass; Seagrass; sediment; site; Soft-sediment habitat; variability
Résumé Accurate predictions of population dynamics require an understanding of the ways by which environmental conditions and species-specific traits affect the magnitude of density dependence. Here, we evaluated the potential impact of season and habitat (characterized by sediment grain size and seagrass biomass) on the magnitude of density dependence in shell growth of 3 infaunal bivalve species dominating the tropical intertidal benthic communities of Banc d'Arguin, Mauritania. Two of our focal species were filter feeders (Senilia senilis and Pelecyora isocardia) and one was a facultative mixotroph (Loripes orbiculatus), mainly relying on organic carbon provided by sulphide-oxidizing endosymbiotic gill-bacteria (i.e. chemosymbiotic). Distinguishing 2 seasons, winter and summer, we manipulated local bivalve densities across habitats (from bare sandy sediments to seagrass-covered mud). In situ growth of individually tagged and relocated clams was measured and compared with those of tagged clams that were allocated to adjacent sites where local bivalve densities were doubled. Growth was negatively density-dependent in both winter and summer in P. isocardia and L. orbiculatus, the 2 species that mainly inhabit seagrass sediments, but not in S. senilis, usually found in bare sediments. As reproduction and survival rates are generally size-dependent in bivalves, our results suggest that in our tropical study system, the bivalve community of seagrass-covered sediments is more strongly regulated than that of adjacent bare sediments, regardless of species-specific feeding mode or season. We suggest that ecosystem engineering by seagrasses enhances environmental stability, which allows bivalve populations within tropical seagrass beds to stay close to carrying capacity.
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ISSN 0171-8630 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2593
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