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Auteur Gounand, I.; Daufresne, T.; Gravel, D.; Bouvier, C.; Bouvier, T.; Combe, M.; Gougat-Barbera, C.; Poly, F.; Torres-Barcelo, C.; Mouquet, N. doi  openurl
  Titre Size evolution in microorganisms masks trade-offs predicted by the growth rate hypothesis Type Article scientifique
  Année 2016 Publication Revue Abrégée Proc. R. Soc. B-Biol. Sci.  
  Volume 283 Numéro 1845 Pages (down) 20162272  
  Mots-Clés Bacteria; bacterial community; biological stoichiometry; cell-size; escherichia-coli; experimental evolution; fresh-water; growth rate hypothesis; inorganic polyphosphate; intrinsic growth; mechanistic approach; Pseudomonas fluorescens; resource competition; r/K strategies; Stoichiometry; variable environment  
  Résumé Adaptation to local resource availability depends on responses in growth rate and nutrient acquisition. The growth rate hypothesis (GRH) suggests that growing fast should impair competitive abilities for phosphorus and nitrogen due to high demand for biosynthesis. However, in microorganisms, size influences both growth and uptake rates, which may mask trade-offs and instead generate a positive relationship between these traits (size hypothesis, SH). Here, we evolved a gradient of maximum growth rate (mu(max)) from a single bacterium ancestor to test the relationship among mu(max), competitive ability for nutrients and cell size, while controlling for evolutionary history. We found a strong positive correlation between mu(max) and competitive ability for phosphorus, associated with a trade-off between mu(max) and cell size: strains selected for high mu(max) were smaller and better competitors for phosphorus. Our results strongly support the SH, while the trade-offs expected under GRH were not apparent. Beyond plasticity, unicellular populations can respond rapidly to selection pressure through joint evolution of their size and maximum growth rate. Our study stresses that physiological links between these traits tightly shape the evolution of competitive strategies.  
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  Editeur Lieu de Publication Éditeur  
  Langue English Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN 0962-8452 ISBN Médium  
  Région Expédition Conférence  
  Notes Approuvé pas de  
  Numéro d'Appel MARBEC @ alain.herve @ collection 2055  
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Auteur Brosset, P.; Lloret, J.; Munoz, M.; Fauvel, C.; Van Beveren, E.; Marques, V.; Fromentin, J.-M.; Menard, F.; Saraux, C. doi  openurl
  Titre Body reserves mediate trade-offs between life-history traits: new insights from small pelagic fish reproduction Type Article scientifique
  Année 2016 Publication Revue Abrégée R. Soc. Open Sci.  
  Volume 3 Numéro 10 Pages (down) 160202  
  Mots-Clés anchovy; clutch size; daily egg-production; empirical-evidence; energy allocation; environmental variability; herring clupea-harengus; maternal effect; mediterranean sardine; northwest Mediterranean; phenotypic plasticity; sardina-pilchardus; sardine; upwelling systems  
  Résumé Limited resources in the environment prevent individuals from simultaneouslymaximizing all life-history traits, resulting in trade-offs. In particular, the cost of reproduction is well known to negatively affect energy investment in growth and maintenance. Here, we investigated these trade-offs during contrasting periods of high versus low fish size and body condition (before/after 2008) in the Gulf of Lions. Female reproductive allocation and performance in anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) were examined based onmorphometric historical data from the 1970s and from 2003 to 2015. Additionally, potential maternal effects on egg quantity and quality were examined in 2014/2015. After 2008, the gonadosomatic index increased for sardine and remained steady for anchovy, while a strong decline in mean length at first maturity indicated earlier maturation for both species. Regarding maternal effects, for both species egg quantity was positively linked to fish size but not to fish lipid reserves, while the egg quality was positively related to lipid reserves. Atresia prevalence and intensity were rather low regardless of fish condition and size. Finally, estimations of total annual numbers of eggs spawned indicated a sharp decrease for sardine since 2008 but a slight increase for anchovy during the last 5 years. This study revealed a biased allocation towards reproduction in small pelagic fish when confronted with a really low body condition. This highlights that fish can maintain high reproductive investment potentially at the cost of other traits which might explain the present disappearance of old and large individuals in the Gulf of Lions.  
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  Langue English Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN 2054-5703 ISBN Médium  
  Région Expédition Conférence  
  Notes Approuvé pas de  
  Numéro d'Appel MARBEC @ alain.herve @ collection 1692  
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Auteur Bonola, M.; Girondot, M.; Robin, J.-P.; Martin, J.; Siegwalt, F.; Jeantet, L.; Lelong, P.; Grand, C.; Chambault, P.; Etienne, D.; Gresser, J.; Hielard, G.; Arque, A.; Regis, S.; Lecerf, N.; Frouin, C.; Lefebvre, F.; Sutter, E.; Vedie, F.; Barnerias, C.; Thieulle, L.; Bordes, R.; Guimera, C.; Aubert, N.; Bouaziz, M.; Pinson, A.; Flora, F.; Duru, M.; Benhalilou, A.; Murgale, C.; Maillet, T.; Andreani, L.; Campistron, G.; Sikora, M.; Rateau, F.; George, F.; Eggenspieler, J.; Woignier, T.; Allenou, J.-P.; Louis-Jean, L.; Chanteur, B.; Beranger, C.; Crillon, J.; Brador, A.; Habold, C.; Maho, Y.L.; Chevallier, D. doi  openurl
  Titre Fine scale geographic residence and annual primary production drive body condition of wild immature green turtles (Chelonia mydas) in Martinique Island (Lesser Antilles) Type Article scientifique
  Année 2019 Publication Revue Abrégée Biol. Open  
  Volume 8 Numéro 12 Pages (down) bio048058  
  Mots-Clés abundance; Biometry; Body condition; Body mass; condition indexes; fitness; Green turtles; growth-rates; Juveniles; length-weight relationships; mass; patterns; regressions; sea-turtles; size  
  Résumé The change of animal biometrics (body mass and body size) can reveal important information about their living environment as well as determine the survival potential and reproductive success of individuals and thus the persistence of populations. However, weighing individuals like marine turtles in the field presents important logistical difficulties. In this context, estimating body mass (BM) based on body size is a crucial issue. Furthermore, the determinants of the variability of the parameters for this relationship can provide information about the quality of the environment and the manner in which individuals exploit the available resources. This is of particular importance in young individuals where growth quality might be a determinant of adult fitness. Our study aimed to validate the use of different body measurements to estimate BM, which can be difficult to obtain in the field, and explore the determinants of the relationship between BM and size in juvenile green turtles. Juvenile green turtles were caught, measured, and weighed over 6 years (2011 2012; 2015 2018) at six bays to the west of Martinique Island (Lesser Antilles). Using different datasets from this global database, we were able to show that the BM of individuals can be predicted from body measurements with an error of less than 2%. We built several datasets including different morphological and time-location information to test the accuracy of the mass prediction. We show a yearly and north – south pattern for the relationship between BM and body measurements. The year effect for the relationship of BM and size is strongly correlated with net primary production but not with sea surface temperature or cyclonic events. We also found that if the bay locations and year effects were removed from the analysis, the mass prediction degraded slightly but was still less than 3% on average. Further investigations of the feeding habitats in Martinique turtles are still needed to better understand these effects and to link them with geographic and oceanographic conditions.  
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  Langue English Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN 2046-6390 ISBN Médium  
  Région Expédition Conférence  
  Notes WOS:000506171400016 Approuvé pas de  
  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2697  
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Auteur Jacquet, C.; Moritz, C.; Morissette, L.; Legagneux, P.; Massol, F.; Archambault, P.; Gravel, D. doi  openurl
  Titre No complexity-stability relationship in empirical ecosystems Type Article scientifique
  Année 2016 Publication Revue Abrégée Nat. Commun.  
  Volume 7 Numéro Pages (down) 12573  
  Mots-Clés biodiversity; body-size; connectance; diversity; ecopath; interaction strengths; models; perturbations; real food webs; systems  
  Résumé Understanding the mechanisms responsible for stability and persistence of ecosystems is one of the greatest challenges in ecology. Robert May showed that, contrary to intuition, complex randomly built ecosystems are less likely to be stable than simpler ones. Few attempts have been tried to test May's prediction empirically, and we still ignore what is the actual complexity-stability relationship in natural ecosystems. Here we perform a stability analysis of 116 quantitative food webs sampled worldwide. We find that classic descriptors of complexity (species richness, connectance and interaction strength) are not associated with stability in empirical food webs. Further analysis reveals that a correlation between the effects of predators on prey and those of prey on predators, combined with a high frequency of weak interactions, stabilize food web dynamics relative to the random expectation. We conclude that empirical food webs have several non-random properties contributing to the absence of a complexity-stability relationship.  
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  Auteur institutionnel Thèse  
  Editeur Lieu de Publication Éditeur  
  Langue English Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN 2041-1723 ISBN Médium  
  Région Expédition Conférence  
  Notes Approuvé pas de  
  Numéro d'Appel MARBEC @ alain.herve @ collection 1638  
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Auteur Tew-Kai, E.; Rossi, V.; Sudre, J.; Weimerskirch, H.; Hernandez-Garcia, E.; Marsac, F.; Garçon, V. doi  openurl
  Titre Top marine predators track Lagrangian coherent structures Type Article scientifique
  Année 2009 Publication Revue Abrégée Proc. Natl. Acad. Sci. U. S. A.  
  Volume 106 Numéro Pages (down) 8245-8250  
  Mots-Clés finite-size Lyapunov exponent; frigatebird; Mozambique Channel; submesoscale  
  Résumé Meso- and submesoscales (fronts, eddies, filaments) in surface ocean flow have a crucial influence on marine ecosystems. Their dynamics partly control the foraging behavior and the displacement of marine top predators (tuna, birds, turtles, and cetaceans). In this work we focus on the role of submesoscale structures in the Mozambique Channel in the distribution of a marine predator, the Great Frigatebird. Using a newly developed dynamic concept, the finite-size Lyapunov exponent (FSLE), we identified Lagrangian coherent structures (LCSs) present in the surface flow in the channel over a 2-month observation period (August and September 2003). By comparing seabird satellite positions with LCS locations, we demonstrate that frigatebirds track precisely these structures in the Mozambique Channel, providing the first evidence that a top predator is able to track these FSLE ridges to locate food patches. After comparing bird positions during long and short trips and different parts of these trips, we propose several hypotheses to understand how frigatebirds can follow these LCSs. The birds might use visual and/or olfactory cues and/or atmospheric current changes over the structures to move along these biologic corridors. The birds being often associated with tuna schools around foraging areas, a thorough comprehension of their foraging behavior and movement during the breeding season is crucial not only to seabird ecology but also to an appropriate ecosystemic approach to fisheries in the channel.  
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  Auteur institutionnel Thèse  
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  Langue Eng Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN 0027-8424 ISBN Médium  
  Région Expédition Conférence  
  Notes Approuvé pas de  
  Numéro d'Appel LL @ pixluser @ collection 30  
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