Résumé
Granitic outcrop vegetation was compared in 22 inselbergs of French Guiana, South America, using RLQ and fourth-corner analyses to identify the main relationships between environmental gradients and plant traits. At the scale of the whole territory the distribution of species and species traits was mostly driven by a spatially-structured gradient embracing regional climate (annual rainfall), forest matrix (canopy openness), and inselberg features (altitude, shape, habitats, summit forest, degree of epiphytism, fire events). Biogeographic, environmental and past historical factors contribute to explain the variation observed at coarse scale and two groups of inselbergs are identified. A first group occupies the southern peneplain in a semi-open forest matrix and exhibits a higher representation of suffrutescent species and climbers, a lower representation of upright shrubs, a lower degree of Guiana Shield endemism, and a higher incidence of human use and autochory. All these features suggest an adaptation to more disturbed environments linked to past climate changes and savannization and to human influences. A second group, characterized by opposite plant traits, occupies the northern part of French Guiana and the far south within a closed forest matrix. Within archipelagos (inselbergs at less than 7 km distance), C-score and Mantel tests revealed a random co-occurrence of plant species and an increase of floristic dissimilarity with distance without any concomitant change in plant traits, respectively, suggesting that spatiallystructured stochastic factors (limitation by dispersal) were the driving force of vegetation change at fine scale.
Auteurs, date et publication :
Auteurs Corinne Sarthou , Sandrine Pavoine , Jean-Pierre Gasc , Jean-Christophe de Massary , Jean-François Ponge
Publication : Flora - Morphology, Distribution, Functional Ecology of Plants
Date : 2025
Volume : 229
Pages : 147-158
Catégorie(s)
#CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs Sandra Ratiarison , Pierre‐Michel FORGET
Publication : Integrative Zoology
Date : 2025
Volume : 6
Issue : 3
Pages : 178-194
Catégorie(s)
#CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs Akihiro Nakamura , Roger L. Kitching , Min Cao , Thomas J. Creedy , Tom M. Fayle , Martin Freiberg , C.N. Hewitt , Takao Itioka , Lian Pin Koh , Keping Ma , Yadvinder Malhi , Andrew Mitchell , Vojtech Novotny , Claire M.P. Ozanne , Liang Song , Han Wang , Louise A. Ashton
Publication : Trends in Ecology & Evolution
Date : 2025
Volume : 32
Issue : 6
Pages : 438-451
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Evergreen plants growing at high latitudes or high elevations may experience freezing events in their photosynthetic tissues. Freezing events can have physical and physiological effects on the leaves which alter leaf optical properties affecting remote and proximal sensing parameters. We froze leaves of six alpine plant species (Soldanella alpina, Ranunculus kuepferi, Luzula nutans, Gentiana acaulis, Geum montanum, and Centaurea uniflora) and three evergreen forest understorey species (Hepatica nobilis, Fragaria vesca and Oxalis acetosella), and assessed their spectral transmittance and optically measured pigments, as well as photochemical efficiency of photosystem II (PSII) as an indicator of freezing damage. Upon freezing, leaves of all the species transmitted more photosynthetically active radiation (PAR) and some species had increased ultraviolet-A (UV-A) transmittance. These differences were less pronounced in alpine than in understorey species, which may be related to higher chlorophyll degradation, visible as reduced leaf chlorophyll content upon freezing in the latter species. Among these understorey forbs, the thin leaves of O. acetosella displayed the largest reduction in chlorophyll (−79%). This study provides insights into how freezing changes the leaf optical properties of wild plants which could be used to set a baseline for upscaling optical reflectance data from remote sensing. Changes in leaf transmittance may also serve to indicate photosynthetic sufficiency and physiological tolerance of freezing events, but experimental research is required to establish this functional association.
Auteurs, date et publication :
Auteurs Twinkle Solanki , José Ignacio García Plazaola , T. Matthew Robson , Beatriz Fernández Marín
Publication : Photochemical & Photobiological Sciences
Date : 2022
Issue : 21
Pages : 997-1009
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Sound emissions from human activities represent a pervasive environmental stressor. Individual responses in terms of behaviour, physiology or anatomy are well documented but whether they propagate through nested ecological interactions to alter complex communities needs to be better understood. This is even more relevant for freshwater ecosystems that harbour a disproportionate fraction of biodiversity but receive less attention than marine and terrestrial systems. We conducted a mesocosm investigation to study the effect of chronic exposure to motorboat noise on the dynamics of a freshwater community including phytoplankton, zooplankton, and roach as a planktivorous fish. As expected under the trophic cascade hypothesis, roach predation induced structural changes in the planktonic communities. Surprisingly, although roach changed their feeding behaviour in response to noise, the dynamics of the roach-dominated planktonic communities did not differ between noisy and noiseless mesocosms. This suggests that the top-down structuring influence of roach on planktonic communities might be resilient to noise and reveals the difficulties on extrapolating impacts form individual responses to complex communities.
Auteurs, date et publication :
Auteurs Emilie Rojas , Mélanie Gouret , Simon Agostini , Sarah Fiorini , Paulo Fonseca , Gérard Lacroix , Vincent Médoc
Date : 2022
Catégorie(s)
#CNRS #ENS #PLANAQUAAuteurs, date et publication :
Auteurs Mario Amalfi , Cony Decock
Publication : Cryptogamie, Mycologie
Date : 2025
Volume : 35
Issue : 1
Pages : 73-86
Catégorie(s)
#CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs Benoît Gauzens , Stéphane Legendre , Xavier Lazzaro , Gérard Lacroix
Publication : Oikos
Date : 2025
Volume : 122
Issue : 11
Pages : 1606-1615
Catégorie(s)
#CNRS #ENS #PLANAQUAAuteurs, date et publication :
Auteurs Olivier Dézerald , Céline Leroy , Bruno Corbara , Jean-François Carrias , Laurent Pélozuelo , Alain Dejean , Régis Céréghino
Publication : PloS one
Date : 2025
Volume : 8
Issue : 8
Pages : e71735
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Dietary methionine affects protein metabolism, lean gain and growth performance and acts in the control of oxidative stress. When supplied in large excess relative to growth requirements in diets for pigs, positive effects on pork quality traits have been recently reported. This study aimed to decipher the molecular and biochemical mechanisms affected by a dietary methionine supply above growth requirements in the loin muscle of finishing pigs. During the last 14 days before slaughter, crossbred female pigs (n = 15 pigs/diet) were fed a diet supplemented with hydroxy-methionine (Met5; 1.1% of methionine) or not (CONT, 0.22% of methionine). Blood was sampled at slaughter to assess key metabolites. At the same time, free amino acid concentrations and expression or activity levels of genes involved in protein or energy metabolism were measured in the longissimus lumborum muscle (LM). The Met5 pigs exhibited a greater activity of creatine kinase in plasma when compared with CONT pigs. The concentrations of free methionine, alpha-aminobutyric acid, anserine, 3-methyl-histidine, lysine, and proline were greater in the LM of Met5 pigs than in CONT pigs. Expression levels of genes involved in protein synthesis, protein breakdown or autophagy were only scarcely affected by the diet. Among ubiquitin ligases, MURF1, a gene known to target creatine kinase and muscle contractile proteins, and OTUD1 coding for a deubiquitinase protease, were up-regulated in the LM of Met5 pigs. A lower activity of citrate synthase, a reduced expression level of ME1 acting in lipogenesis but a higher expression of PPARD regulating energy metabolism, were also observed in the LM of Met5 pigs compared with CONT pigs. Principal component analysis revealed that expression levels of many studied genes involved in protein and energy metabolism were correlated with meat quality traits across dietary treatments, suggesting that subtle modifications in expression of those genes had cumulative effects on the regulation of processes leading to the muscle transformation into meat. In conclusion, dietary methionine supplementation beyond nutritional requirements in pigs during the last days before slaughter modified the free amino acid profile in muscle and its redox capacities, and slightly affected molecular pathways related to protein breakdown and energy metabolism. These modifications were associated with benefits on pork quality traits.
Auteurs, date et publication :
Auteurs Florence Gondret , Nathalie Floc'h , Dolores I. Batonon-Alavo , Marie-Hélène Perruchot , Yves Mercier , Bénédicte Lebret
Publication : Animal
Date : 2021
Volume : 15
Pages : 100268
Catégorie(s)
#CNRS #EcoGenO #Université de RennesAuteurs, date et publication :
Auteurs Eva Ringler , Andrius Pašukonis , W Tecumseh Fitch , Ludwig Huber , Walter Hödl , Max Ringler
Publication : Behavioral Ecology
Date : 2025
Volume : 26
Issue : 4
Pages : 1219-1225