Résumé
Stress hormones and their impacts on whole organism metabolic rates are usually considered as appropriate proxies for animal energy budget that is the foundation of numerous concepts and models aiming at predicting individual and population responses to environmental stress. However, the dynamics of energy re-allocation under stress make the link between metabolism and corticosterone complex and still unclear. Using ectopic application of corticosterone for 3, 11 and 21 days, we estimated a time effect of stress in a lizard (Zootoca vivipara). We then investigated whole organism metabolism, muscle cellular O-2 consumption and liver mitochondrial oxidative phosphorylation processes (O-2 consumption and ATP production) and ROS production. The data showed that while skeletal muscle is not impacted, stress regulates the liver mitochondrial functionality in a time-dependent manner with opposing pictures between the different time expositions to corticosterone. While 3 days exposition is characterized by lower ATP synthesis rate and high H2O2 release with no change in the rate of oxygen consumption, the 11 days exposition reduced all three fluxes of about 50%. Oxidative phosphorylation capacities in liver mitochondria of lizard treated with corticosterone for 21 days was similar to the hepatic mitochondrial capacities in lizards that received no corticosterone treatment but with 40% decrease in H2O2 production. This new mitochondrial functioning allows a better capacity to respond to the energetic demands imposed by the environment but do not influence whole organism metabolism. In conclusion, global mitochondrial functioning has to be considered to better understand the proximal causes of the energy budget under stressful periods.
Auteurs, date et publication :
Auteurs Yann Voituron , Damien Roussel , Jean-Francois Le Galliard , Andreaz Dupoue , Caroline Romestaing , Sandrine Meylan
Publication : JOURNAL OF COMPARATIVE PHYSIOLOGY B-BIOCHEMICAL SYSTEMS AND ENVIRONMENTAL PHYSIOLOGY
Date : 2022
Volume : 192
Issue : 6
Pages : 765-774
Catégorie(s)
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Pre-copulatory female mate choice based on male ultraviolet (UV) coloration has been demonstrated in several vertebrate species; however, post-copulatory mechanisms have been largely overlooked. Here, we investigated female mate preference based on male UV coloration in the common lizard Zootoca vivipara, in which males display conspicuous UV coloration on their throat. During two successive years, we staged sequential mating trials between females and four different males with UV-reduced or control belly and throat coloration. We recorded pre-copulatory female behaviour, copulation behaviour and assigned paternity to all offspring. Females were more aggressive towards UV-reduced males and, during the second year, UV-reduced males had a lower probability of siring at least one egg (fertilization success) during the last mating trials. However, in the second year, copulation was shorter with control males. Altogether, our results suggest that females exert subtle pre-copulatory mate preference based on male UV ornaments and, conditional on the study year and female mating history, some degree of post-copulatory preference for UV-control males leading to differential male fertilization success. This study suggests that UV-based female mate choice may be more widespread than previously thought in vertebrates, and emphasizes the importance of using a study design well adapted to the species reproductive behaviour.
Auteurs, date et publication :
Auteurs Arnaud Badiane , Melissa Martin , Sandrine Meylan , Murielle Richard , Beatriz Decenciere Ferrandiere , Jean-Francois Le Galliard
Publication : BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY
Date : 2020
Volume : 130
Issue : 3
Pages : 586-598
Catégorie(s)
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Analysis of 65 grasslands worldwide from the Nutrient Network experiment reveals that plant communities with higher α- and β-diversity have higher levels of ecosystem multifunctionality, and that this effect is amplified across scales.
Auteurs, date et publication :
Auteurs Yann Hautier , Forest Isbell , Elizabeth T. Borer , Eric W. Seabloom , W. Stanley Harpole , Eric M. Lind , Andrew S. MacDougall , Carly J. Stevens , Peter B. Adler , Juan Alberti , Jonathan D. Bakker , Lars A. Brudvig , Yvonne M. Buckley , Marc Cadotte , Maria C. Caldeira , Enrique J. Chaneton , Chengjin Chu , Pedro Daleo , Christopher R. Dickman , John M. Dwyer
Publication : Nature Ecology & Evolution
Date : 2018
Volume : 2
Issue : 1
Pages : 50
Catégorie(s)
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1. Parenting is costly and because the relationship between the mother and embryos is not mutualistic, mother-offspring conflicts may exist whenever resource are scarce. However, intergenerational trade-offs and conflicts resulting from limited access to water, a vital and depreciable resource, remain largely overlooked. 2. In this study, we examined the physiological, reproductive and life-history responses to water restriction in the European Common Lizard (Zootoca vivipara). We hypothesized that, under water-limited conditions, pregnant females experience both short-term and long-term physiological impacts (dehydration and stress) underlying an allocation trade-off for water between mothers and offspring. 3.Water restriction led to a decrease in body mass, and an increase in plasma osmolality (dehydration) and corticosterone concentration in both males and females. The extent of the dehydration was positively correlated with fecundity in females. This suggests a trade-off between maternal water balance and allocation of water to developing embryos during reproduction. 4. Water restriction had no immediate effect on reproductive output or offspring morphology at birth. Yet, water restriction in pregnant females enhanced their reproductive effort the following year but reduced the early life growth and annual survival of their second-year offspring. 5. These delayed fitness responses to water restriction in offspring and mothers suggest that water can trigger intergenerational conflicts as demonstrated for energy. Although the mediation of this conflict remains to be clarified, we hypothesized that it represents a selective force that influences reproductive strategies.
Auteurs, date et publication :
Auteurs Andreaz Dupoue , Jean-Francois Le Galliard , Remy Josserand , Dale F. DeNardo , Beatriz Decenciere , Simon Agostini , Claudy Haussy , Sandrine Meylan
Publication : FUNCTIONAL ECOLOGY
Date : 2018
Volume : 32
Issue : 3
Pages : 676-686
Catégorie(s)
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In many grasslands, species with specific traits occupy unique temporal positions within communities. Such intra-annual segregation is predicted to be greatest in systems with high intra-annual climate variability because fluctuating environmental conditions provide opportunities for temporal niche partitioning among species. However, because most studies on intra-annual community dynamics have been conducted at individual sites, relationships between intra-annual climate variability and seasonal community dynamics at global scales have not yet been identified. Furthermore, the same characteristics that promote species-specific responses to fluctuations in environmental conditions may also drive species-specific responses to global change drivers such as eutrophication. Research provides evidence that eutrophication alters inter-annual plant community dynamics yet understanding of how it alters intra-annual dynamics remains limited.
We used early-season and late-season compositional data collected from 10 grassland sites around the world to ask how intra-annual variability in precipitation and temperature as well as nutrient enrichment shape intra-annual species segregation, or seasonal β-diversity, in plant communities. We also assessed whether changes in the abundances of specific functional groups including annual forbs, perennial forbs, C3 and C4 graminoids, and legumes underpin compositional differences between early- and late-season communities and treatments. We found that intra-annual temperature variability and seasonal β-diversity were positively related but observed no relationship between intra-annual precipitation variability and seasonal β-diversity. This suggests that positive relationships between α-diversity and intra-annual temperature variability identified in earlier studies may be underpinned by the positive influence of intra-annual temperature variability on temporal segregation of species within growing seasons. We found that nutrient enrichment increased seasonal β-diversity via increased turnover of species between early- and late-season communities. This finding mirrors patterns observed at inter-annual scales and suggests fertilization can alter compositional dynamics via similar mechanisms at varied temporal scales. Finally, fertilization reduced the abundance of C4 graminoids and legumes and eliminated intra-annual differences in these groups. In contrast, fertilization resulted in intra-annual differences in C3 graminoids which were not observed in control conditions, and increased abundance of C3 graminoids and annual forbs overall. Our study provides new insight into how intra-annual climate variability and nutrient enrichment influence biodiversity and seasonal dynamics in global grasslands.
Auteurs, date et publication :
Auteurs Magda Garbowski , Elizabeth Boughton , Anne Ebeling , Philip Fay , Yann Hautier , Hanna Holz , Anke Jentsch , Stephanie Jurburg , Emma Ladouceur , Jason Martina , Timothy Ohlert , Xavier Raynaud , Christiane Roscher , Grégory Sonnier , Pedro Maximiliano Tognetti , Laura Yahdjian , Peter Wilfahrt , Stan Harpole
Date : 2023
Catégorie(s)
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Human activities are enriching many of Earth’s ecosystems with biologically limiting mineral nutrients such as nitrogen (N) and phosphorus (P). In grasslands, this enrichment generally reduces plant diversity and increases productivity. The widely demonstrated positive effect of diversity on productivity suggests a potential negative feedback, whereby nutrient-induced declines in diversity reduce the initial gains in productivity arising from nutrient enrichment. In addition, plant productivity and diversity can be inhibited by accumulations of dead biomass, which may be altered by nutrient enrichment. Over longer timeframes, nutrient addition may increase soil fertility by increasing soil organic matter and nutrient pools. We examined the effects of 5-11 years of nutrient addition at 47 grasslands in twelve countries. Nutrient enrichment increased aboveground live biomass and reduced plant diversity at nearly all sites, and these effects became stronger over time. We did not find evidence that nutrient-induced losses of diversity reduced the positive effects of nutrients on biomass, however nutrient effects on live biomass increased more slowly at sites where litter was also increasing, regardless of plant diversity. This work suggests that short-term experiments may underestimate the long-term nutrient enrichment effects on global, grassland ecosystems.
Auteurs, date et publication :
Auteurs Eric W. Seabloom , Peter B. Adler , Juan Alberti , Lori Biederman , Yvonne M. Buckley , Marc W. Cadotte , Scott L. Collins , Laura Dee , Philip A. Fay , Jennifer Firn , Nicole Hagenah , W. Stanley Harpole , Yann Hautier , Andy Hector , Sarah E. Hobbie , Forest Isbell , Johannes M. H. Knops , Kimberly J. Komatsu , Ramesh Laungani , Andrew MacDougall
Publication : Ecology
Date : 2025
Volume : n/a
Issue : n/a
Catégorie(s)
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Global changes will modify future nutrient availability with implications for grassland biogeochemistry. Soil organic matter (SOM) is central to grasslands for both provision of nutrients and climate mitigation through carbon (C) storage. While we know that C and nitrogen (N) in SOM can be influenced by greater nutrient availability, we lack understanding of nutrient effects on C and N coupling and stability in soil. Different SOM fractions have different functional relevance and mean residence times, i.e., mineral-associated organic matter (MAOM) has a higher mean residence time than particulate organic matter (POM). By separating effects of nutrient supply on the different SOM fractions, we can better evaluate changes in soil C and N coupling and stability and associated mechanisms. To this end, we studied responses of C and N ratios and distributions across POM and MAOM to 6–10 years of N, phosphorus (P), potassium and micronutrients (K+µ), and combined NPK+µ additions at 11 grassland sites spanning 3 continents and globally relevant environmental gradients in climate, plant growth, soil texture, and nutrient availability. We found addition of N and NPK+µ generally reduced C:N in MAOM and POM. However, at low fertility and at warm, sandy sites, nutrient addition promoted higher MAOM and POM C:N, respectively. Addition of NPK+µ also promoted C storage in POM relative to MAOM, and this was consistent across sites. Our results suggest that addition of macro- and micronutrients consistently decrease SOM stabilization, whereas responses of soil C:N stoichiometry were contingent on SOM fraction and environmental conditions.
Auteurs, date et publication :
Auteurs Katherine S. Rocci , Kaydee S. Barker , Eric W. Seabloom , Elizabeth T. Borer , Sarah E. Hobbie , Jonathan D. Bakker , Andrew S. MacDougall , Rebecca L. McCulley , Joslin L. Moore , Xavier Raynaud , Carly J. Stevens , M. Francesca Cotrufo
Publication : Biogeochemistry
Date : 2022
Volume : 159
Issue : 3
Pages : 353-370
Catégorie(s)
#ANR-Citation #CEREEP #CNRS #ENSRésumé
Experiments comparing diploids with polyploids and in single grassland sites show that nitrogen and/or phosphorus availability influences plant growth and community composition dependent on genome size; specifically, plants with larger genomes grow faster under nutrient enrichments relative to those with smaller genomes. However, it is unknown if these effects are specific to particular site localities with speciifc plant assemblages, climates, and historical contingencies. To determine the generality of genome size-dependent growth responses to nitrogen and phosphorus fertilization, we combined genome size and species abundance data from 27 coordinated grassland nutrient addition experiments in the Nutrient Network that occur in the Northern Hemisphere across a range of climates and grassland communities. We found that after nitrogen treatment, species with larger genomes generally increased more in cover compared to those with smaller genomes, potentially due to a release from nutrient limitation. Responses were strongest for C3 grasses and in less seasonal, low precipitation environments, indicating that genome size effects on water-use-efficiency modulates genome size–nutrient interactions. Cumulatively, the data suggest that genome size is informative and improves predictions of species’ success in grassland communities.
Auteurs, date et publication :
Auteurs Joseph A. Morton , Carlos Alberto Arnillas , Lori Biedermann , Elizabeth T. Borer , Lars A. Brudvig , Yvonne M. Buckley , Marc W. Cadotte , Kendi Davies , Ian Donohue , Anne Ebeling , Nico Eisenhauer , Catalina Estrada , Sylvia Haider , Yann Hautier , Anke Jentsch , Holly Martinson , Rebecca L. McCulley , Xavier Raynaud , Christiane Roscher , Eric W. Seabloom
Publication : PLOS Biology
Date : 2025
Volume : 22
Issue : 12
Pages : e3002927
Catégorie(s)
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Reductions in community evenness can lead to local extinctions as dominant species exclude subordinate species; however, herbivores can prevent competitive exclusion by consuming otherwise dominant plant species, thus increasing evenness. While these predictions logically result from chronic, gradual reductions in evenness, rapid, temporary pulses of dominance may also reduce species richness. Short pulses of dominance can occur as biotic or abiotic conditions temporarily favour one or a few species, manifested as increased temporal variability (the inverse of temporal stability) in community evenness. Here, we tested whether consumers help maintain plant diversity by reducing the temporal variability in community evenness. We tested our hypothesis by reducing herbivore abundance in a detailed study of a developing, tallgrass prairie restoration. To assess the broader implications of the importance of herbivory on community evenness as well as potential mechanisms, we paired this study with a global herbivore reduction experiment. We found that herbivores maintained plant richness in a tallgrass prairie restoration by limiting temporary pulses in dominance by a single species. Dominance by an annual species in a single year was negatively associated with species richness, suggesting that short pulses of dominance may be sufficient to exclude subordinate species. The generality of this site-level relationship was supported by the global experiment in which inter-annual variability in evenness declined in the presence of vertebrate herbivores over timeframes ranging in length from 2 to 5 years, preventing declines in species richness. Furthermore, inter-annual variability of community evenness was also negatively associated with pre-treatment species richness. Synthesis. A loss or reduction of herbivores can destabilize plant communities by allowing brief periods of dominance by one or a few species, potentially triggering a feedback cycle of dominance and extinction. Such cycles may not occur immediately following the loss of herbivores, being delayed until conditions allow temporary periods of dominance by a subset of plant species.
Auteurs, date et publication :
Auteurs Brent Mortensen , Brent Danielson , W. Stanley Harpole , Juan Alberti , Carlos Alberto Arnillas , Lori Biederman , Elizabeth T. Borer , Marc W. Cadotte , John M. Dwyer , Nicole Hagenah , Yann Hautier , Pablo Luis Peri , Eric W. Seabloom
Publication : Journal of Ecology
Date : 2025
Volume : 106
Issue : 1
Pages : 101-112
Catégorie(s)
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Eutrophication is a widespread environmental change that usually reduces the stabilizing effect of plant diversity on productivity in local communities. Whether this effect is scale dependent remains to be elucidated. Here, we determine the relationship between plant diversity and temporal stability of productivity for 243 plant communities from 42 grasslands across the globe and quantify the effect of chronic fertilization on these relationships. Unfertilized local communities with more plant species exhibit greater asynchronous dynamics among species in response to natural environmental fluctuations, resulting in greater local stability (alpha stability). Moreover, neighborhood communities that have greater spatial variation in plant species composition within sites (higher beta diversity) have greater spatial asynchrony of productivity among communities, resulting in greater stability at the larger scale (gamma stability). Importantly, fertilization consistently weakens the contribution of plant diversity to both of these stabilizing mechanisms, thus diminishing the positive effect of biodiversity on stability at differing spatial scales. Our findings suggest that preserving grassland functional stability requires conservation of plant diversity within and among ecological communities.
Auteurs, date et publication :
Auteurs Yann Hautier , Pengfei Zhang , Michel Loreau , Kevin R. Wilcox , Eric W. Seabloom , Elizabeth T. Borer , Jarrett E. K. Byrnes , Sally E. Koerner , Kimberly J. Komatsu , Jonathan S. Lefcheck , Andy Hector , Peter B. Adler , Juan Alberti , Carlos A. Arnillas , Jonathan D. Bakker , Lars A. Brudvig , Miguel N. Bugalho , Marc Cadotte , Maria C. Caldeira , Oliver Carroll
Publication : Nature Communications
Date : 2020
Volume : 11
Issue : 1
Pages : 5375