Résumé
Hormones play a fundamental role in mediating social behaviors of animals. However, it is less well understood to what extent behavioral variation between individuals can be attributed to variation in underlying hormonal profiles. The goal of the present study was to infer if individual androgen levels, and/or the modulation thereof, can explain among-individual variation in aggressiveness, boldness and exploration. We used as a model the dartpoison frog Allobates femoralis and took repeated non-invasive water-borne hormonal samples of individual males before (baseline) and after (experimental) a series of behavioral tests for assessing aggression, boldness, and exploratory tendency. Our results show that androgen levels in A. femoralis are quite stable across the repro ductive season. Repeatability in wbT baseline levels was high, while time of day, age of the frog, and trial order did not show any significant impact on measured wbT levels. In general, experimental wbT levels after behavioral tests were lower compared to the respective baseline levels. However, we identified two different patterns with regard to androgen modulation in response to behavioral testing: individuals with low baseline wbT tended to have increased wbT levels after the behavioral testing, while individuals with comparatively high baseline wbT levels rather showed a decrease in hormonal levels after testing. Our results also suggest that baseline wbT levels are linked to the personality trait exploration, and that androgen modulation is linked to boldness in A. femoralis males. These results show that differences in hormonal profiles and/or hormonal modulation in response to social challenges can indeed explain among-individual differences in behavioral traits.
Auteurs, date et publication :
Auteurs Eva Ringler , Katharina Dellefont , Mélissa Peignier , Virginie Canoine
Publication : General and Comparative Endocrinology
Date : 2025
Volume : 346
Pages : 114416
Catégorie(s)
#CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs Florian Menzel , Jérôme Orivel , Martin Kaltenpoth , Thomas Schmitt
Publication : Chemoecology
Date : 2025
Volume : 24
Issue : 3
Pages : 105-119
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Whether the success of alien species can be explained by their functional or phylogenetic characteristics remains unresolved because of data limitations, scale issues and weak quantifications of success. Using permanent grasslands across France (50 000 vegetation plots, 2000 species, 130 aliens) and building on the Rabinowitz’s classification to quantify spread, we showed that phylogenetic and functional similarities to natives were the most important correlates of invasion success compared to intrinsic functional characteristics and introduction history. Results contrasted between spatial scales and components of invasion success. Widespread and common aliens were similar to co-occurring natives at coarse scales (indicating environmental filtering), but dissimilar at finer scales (indicating local competition). In contrast, regionally widespread but locally rare aliens showed patterns of competitive exclusion already at coarse scale. Quantifying trait differences between aliens and natives and distinguishing the components of invasion success improved our ability to understand and potentially predict alien spread at multiple scales.
Auteurs, date et publication :
Auteurs Marta Carboni , Tamara Münkemüller , Sébastien Lavergne , Philippe Choler , Benjamin Borgy , Cyrille Violle , Franz Essl , Cristina Roquet , François Munoz , DivGrass Consortium , Wilfried Thuiller , Elsa Cleland
Publication : Ecology Letters
Date : 2025
Volume : 19
Issue : 3
Pages : 219-229
Catégorie(s)
#CNRS #Lautaret #UGAAuteurs, date et publication :
Auteurs Céline Leroy , Bruno Corbara , Olivier Dézerald , M. Kurtis Trzcinski , Jean-François Carrias , Alain Dejean , Régis Céréghino
Publication : Hydrobiologia
Date : 2025
Volume : 802
Issue : 1
Pages : 85-95
Catégorie(s)
#CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs Mickal Houadria , Florian Menzel
Publication : Oecologia
Date : 2025
Volume : 184
Issue : 4
Pages : 885-899
Catégorie(s)
#CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs Neil E. Coughlan , James W.E. Dickey , Jaimie T.A. Dick , Vincent Médoc , Monica McCard , Gérard Lacroix , Sarah Fiorini , Alexis Millot , Ross N. Cuthbert
Publication : Science of The Total Environment
Date : 2025
Volume : 843
Pages : 156876
Catégorie(s)
#ANR-Citation #CNRS #ENS #PLANAQUARésumé
The topographical heterogeneity of mountain landscapes and the associated species turnover over short distances should prompt us to examine the relationships between climate and mountain plant distribution at a much finer scale than is commonly done. Here, I focused on the root zone temperature experienced by lowstature perennial-dominated plant communities of temperate mountains, which are seasonally covered by snow. Based on the analysis of multi-annual recordings of ground temperatures across a broad spectrum of plant communities, I propose a habitat template using Growing Degree Days (GDD) and Freezing Degree Days (FDD). These two indices summarize soil thermal conditions experienced during the favorable and the unfavorable period for growth. This heuristic framework allows refining our working hypotheses on the range shifts of mountain plants in response to recent and future climate change. Regional trends in climate variables controlling GDD and FDD indicate that the combination of earlier snow melt-out and higher summer temperatures have led to an overall increase in GDD over the last decades. However the persistence of cold episodes in spring and in fall along with the shorter snow coverage suggest that the positive effect of an extended growing season might be counteracted by the detrimental effects of increasing FDD. I thus hypothesize (i) a local-scale, downward shift of plant species along mesotopographical gradients, with marked species infilling in sparsely vegetated, longlasting snow patches that contain vacant niches and (ii) a watershed-scale upward shift of subalpine species inhabiting south-exposed grasslands and able to cope with moderate FDD. This perspective challenges the simplistic view of an overall range shift of mountain plants along elevational gradients and calls for the improvement of models of snow cover dynamics and root zone temperature to draw up realistic scenarios of mountain vegetation changes under a warmer climate.
Auteurs, date et publication :
Auteurs P. Choler
Publication : Perspectives in Plant Ecology, Evolution and Systematics
Date : 2025
Volume : 30
Pages : 6-15
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Extreme wind blowdown events can significantly modify the structure and composition of forests, and the predicted shift in tropical cyclone regimes due to climate change could strongly impact forests across the tropics. In this study, we coupled an individual-based and spatially-explicit forest dynamics model (TROLL) with a mechanistic model estimating wind damage as a function of tree size, traits, and allometry (ForestGALES). We assimilated floristic trait data and climate data from a subtropical forest site in Taiwan to explore the effect of wind regimes on forest properties. We found that the average canopy height and biomass stocks decreased as wind disturbance strength increased, but biomass stocks showed a nonlinear response. Above a wind intensity threshold, both canopy height and biomass drastically decreased to near-zero, exhibiting a transition to a non-forest state. Wind intensity strongly regulated wind impact, but varying wind frequency did not cause discernible effects. The implementation of within-stand topographic heterogeneity led to weak effects on within-stand forest structure heterogeneity at the study site. In conclusion, the intensity of wind disturbances can potentially greatly impact forest structure by modifying mortality. Individual-based modeling provides a framework in which to investigate the impact of wind regimes on mortality, other factors influencing wind-induced tree mortality, as well as interaction between wind and other forms of forest disturbance and human land use legacy.
Auteurs, date et publication :
Auteurs E-Ping Rau , Barry A. Gardiner , Fabian Joerg Fischer , Isabelle Marechaux , Emilie Joetzjer , I-Fang Sun , Jerome Chave
Publication : FRONTIERS IN FORESTS AND GLOBAL CHANGE
Date : 2022
Volume : 5
Catégorie(s)
#ANR-Citation #CNRS #FORET NouraguesRésumé
The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) is a purported agent of decline and extinction of many amphibian populations worldwide. Its occurrence remains poorly documented in many tropical regions, including the Guiana Shield, despite the area's high amphibian diversity. We conducted a comprehensive assessment of Bd in French Guiana in order to (1) determine its geographical distribution, (2) test variation of Bd prevalence among species in French Guiana and compare it to earlier reported values in other South American anuran species (http://www.bd-maps.net; 123 species from 15 genera) to define sentinel species for future work, (3) track changes in prevalence through time and (4) determine if Bd presence had a negative effect on one selected species. We tested the presence of Bd in 14 species at 11 sites for a total of 1053 samples (306 in 2009 and 747 in 2012). At least one Bd-positive individual was found at eight out of 11 sites, suggesting a wide distribution of Bd in French Guiana. The pathogen was not uniformly distributed among the studied amphibian hosts, with Dendrobatidae species displaying the highest prevalence (12.4%) as compared to Bufonidae (2.6%) and Hylidae (1.5%). In contrast to earlier reported values, we found highest prevalence for three Dendrobatidae species and two of them displayed an increase in Bd prevalence from 2009 to 2012. Those three species might be the sentinel species of choice for French Guiana. For Dendrobates tinctorius, of key conservation value in the Guiana Shield, smaller female individuals were more likely to be infected, suggesting either that frogs can outgrow their chytrid infections or that the disease induces developmental stress limiting growth. Generally, our study supports the idea that Bd is more widespread than previously thought and occurs at remote places in the lowland forest of the Guiana shield.
Auteurs, date et publication :
Auteurs Elodie A. Courtois , Philippe Gaucher , Jerome Chave , Dirk S. Schmeller
Publication : PLOS ONE
Date : 2015
Volume : 10
Issue : 4
Catégorie(s)
#ANR-Citation #CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs Renaud Boistel , Thierry Aubin , Peter Cloetens , Max Langer , Brigitte Gillet , Patrice Josset , Nicolas Pollet , Anthony Herrel
Publication : PloS one
Date : 2025
Volume : 6
Issue : 7
Pages : e22080