Résumé
Anticipating the genetic and phenotypic changes induced by natural or artificial selection requires reliable estimates of trait evolvabilities (genetic variances and covariances). However, whether or not multivariate quantitative genetics models are able to predict precisely the evolution of traits of interest, especially fitness-related, life-history traits, remains an open empirical question. Here, we assessed to what extent the response to bivariate artificial selection on both body size and maturity in the medaka Oryzias latipes, a model fish species, fits the theoretical predictions. Three populations were selected for divergent body size while maintaining a constant selection pressure against late maturity. The observed evolutionary trends did not match the predictions from a bivariate quantitative genetics "animal" model. The most parsimonious model identified environmental, but not genetic, covariances between both traits, which cannot explain why body size did not evolve in the line selected for a smaller body length. We investigated alternative mechanisms (including genetic drift, inbreeding depression, natural selection, scaling or genetic asymmetry issues, and undetected genetic correlations) but could not attribute the deviation from theory to any single explanation. Overall, these results question the ability of multivariate quantitative models to provide valid and operational predictions of the evolutionary response to multivariate selection on complex traits.
Auteurs, date et publication :
Auteurs Arnaud Le Rouzic , Clémentine Renneville , Alexis Millot , Simon Agostini , David Carmignac , Éric Édeline
Publication : bioRxiv
Date : 2020
Pages : 2020.01.23.916361
Catégorie(s)
#CNRS #ENS #PLANAQUARésumé
Anthropogenic perturbations such as harvesting often select against a large body size, and are predicted to induce rapid evolution towards smaller body sizes and earlier maturation. However, the evolvability of body size and size-correlated traits remains seldom evaluated in wild populations. Here, we use a laboratory experiment over 6 generations to measure the ability of wild-caught medaka fish (Oryzias latipes) to evolve in response to bidirectional size-dependent selection mimicking opposite harvest regimes. Specifically, we imposed selection against a small body size (Large line), against a large body size (Small line) or random selection (Control line), and measured correlated responses across multiple phenotypic, life-history and endocrine traits. As expected, the Large line evolved faster somatic growth and delayed maturation, but also evolved smaller body sizes at hatch, with no change in average levels of pituitary gene expressions of luteinizing, follicle-stimulating or growth (GH) hormones. In contrast, the Small medaka line was unable to evolve smaller body sizes or earlier maturation, but showed marginally-significant signs of increased reproductive investment (age effect on maturity probability, larger egg sizes, elevated pituitary GH production). Natural selection on medaka body size was too weak to significantly hinder the effect of artificial selection, indicating that the asymmetric body-size response to size-dependent selection reflected an asymmetry in body-size evolvability. Our results show that trait evolvability may be contingent upon the direction of selection, and that a detailed knowledge of trait evolutionary potential is needed to forecast population response to anthropogenic change.
Auteurs, date et publication :
Auteurs Clémentine Renneville , Alexis Millot , Simon Agostini , David Carmignac , Gersende Maugars , Sylvie Dufour , Arnaud Le Rouzic , Eric Edeline
Publication : bioRxiv
Date : 2020
Pages : 498683
Catégorie(s)
#CNRS #ENS #PLANAQUARésumé
Extreme climatic events (ECEs) such as droughts and heat waves affect ecosystem functioning and species turnover. This study investigated the effect of elevated CO2 on species’ resilience to ECEs. Monoliths of intact soil and their plant communities from an upland grassland were exposed to 2050 climate scenarios with or without an ECE under ambient (390 ppm) or elevated (520 ppm) CO2. Ecophysiological traits of two perennial grasses (Dactylis glomerata and Holcus lanatus) were measured before, during, and after ECE. At similar soil water content, leaf elongation was greater under elevated CO2 for both species. The resilience of D. glomerata increased under enhanced CO2 (+60%) whereas H. lanatus mostly died during ECE. D. glomerata accumulated 30% more fructans, which were more highly polymerized, and 4-fold less sucrose than H. lanatus. The fructan concentration in leaf meristems was significantly increased under elevated CO2. Their relative abundance changed during the ECE, resulting in a more polymerized assemblage in H. lanatus and a more depolymerized assemblage in D. glomerata. The ratio of low degree of polymerization fructans to sucrose in leaf meristems was the best predictor of resilience across species. This study underlines the role of carbohydrate metabolism and the species-dependent effect of elevated CO2 on the resilience of grasses to ECE.
Auteurs, date et publication :
Auteurs Florence Volaire , Annette Morvan-Bertrand , Marie-Pascale Prud’homme , Marie-Lise Benot , Angela Augusti , Marine Zwicke , Jacques Roy , Damien Landais , Catherine Picon-Cochard
Publication : Journal of Experimental Botany
Date : 2020
Volume : 71
Issue : 1
Pages : 370-385
Catégorie(s)
#ANR-Citation #CNRS #Ecotron de MontpellierRésumé
Animals use a variety of strategies to avoid acute dehydration and death. Yet, how chronic exposure to sub-lethal dehydration may entail physiological and fitness costs remains elusive. In this study, we experimentally tested if water restriction causes increased oxidative stress (OS) and telomere length (TL) shortening, two well-described mediators of environment-fitness relationships. We exposed 100 yearling female and male common lizards (Zootoca vivipara) either to a 51-day period of water restriction or to water ad libitum, followed by 45 days in common garden outdoor conditions. We measured the kinetic changes in OS and TL and found that water-restricted males had enhanced antioxidant defences and decreased oxidative damage at day 36, whereas females did not immediately respond. A month and a half after water restriction, both sexes experienced a drop in antioxidant capacity but only males exhibited significant TL shortening. In the following 3 years, we found that lizards with longer initial TL and those who maintained stronger antioxidant defences experienced higher longevity, irrespective of sex and water restriction. Together, these results unravelled sex-specific responses to water restriction, with potential applications in better understanding the physiological costs of increasing summer droughts as a result of global climate change.
Auteurs, date et publication :
Auteurs Andreaz Dupoue , Frederic Angelier , Cecile Ribout , Sandrine Meylan , David Rozen-Rechels , Beatriz Decenciere , Simon Agostini , Jean-Francois Le Galliard
Publication : BIOLOGY LETTERS
Date : 2020
Volume : 16
Issue : 2
Catégorie(s)
#ANR-Citation #CEREEP #CNRS #ENSRésumé
Severe drought and extreme heat associated with the 2015–2016 El Niño event have led to large carbon emissions from the tropical vegetation to the atmosphere. With the return to normal climatic conditions in 2017, tropical forest aboveground carbon (AGC) stocks are expected to partly recover due to increased productivity, but the intensity and spatial distribution of this recovery are unknown. We used low-frequency microwave satellite data (L-VOD) to feature precise monitoring of AGC changes and show that the AGC recovery of tropical ecosystems was slow and that by the end of 2017, AGC had not reached predrought levels of 2014. From 2014 to 2017, tropical AGC stocks decreased by
1.31.21.5
Pg C due to persistent AGC losses in Africa (
−0.9−1.1−0.8
Pg C) and America (
−0.5−0.6−0.4
Pg C). Pantropically, drylands recovered their carbon stocks to pre–El Niño levels, but African and American humid forests did not, suggesting carryover effects from enhanced forest mortality.
Auteurs, date et publication :
Auteurs Jean-Pierre Wigneron , Lei Fan , Philippe Ciais , Ana Bastos , Martin Brandt , Jérome Chave , Sassan Saatchi , Alessandro Baccini , Rasmus Fensholt
Publication : Science Advances
Date : 2020
Volume : 6
Issue : 6
Pages : eaay4603
Catégorie(s)
#ANR-Citation #CNRS #FORET NouraguesRésumé
Plant roots are inhabited by a diversity of microorganisms known to be key drivers of plant growth and health. Although the rules governing root microbiota assembly have been investigated and the importance of abiotic determinants highlighted, the consequences of the biotic context of the plant community have often been overlooked. We tested the hypothesis that the abundance of species in a given plant neighborhood could leave a fingerprint on its root-endophytic fungal community, ultimately impacting its biomass. Outdoor experimental mesocosms, comprising a range of floristic compositions and spatially mapped plant distributions, were monitored for 2y. Medicago truncatula was used as trap-plant and grown under standardized conditions on soil samples collected in the mesocosms. The root-endophytic fungal community of M. truncatula was described by amplicon mass sequencing and M. truncatula performance was also assessed. The richness and evenness of M. truncatula's root-endophytic fungal community were explained by the small-scale plant neighborhood of the soil samples. For instance, the occurrence of Brachypodium pinnatum in the neighborhood induced higher and lower richness of Sordariomycetes and Glomeromycetes, respectively, whereas Holcus mollis decreased the OTU evenness of the entire mycobiota. These changes in fungal clade OTU richness and evenness were related to modifications in the biomass of M. truncatula. These results indicate that a given plant endophytic fungal community is determined in part by the neighboring plants. Considering that changes in endophytic fungal community are correlated with the plant biomass, this suggests that plant-plant interactions (i.e. competition, facilitation) impacting plant biomass can be mediated by endophytic fungal community changes.
Auteurs, date et publication :
Auteurs Nathan Vannier , Anne-Kristel Bittebiere , Cendrine Mony , Philippe Vandenkoornhuyse
Publication : Fungal Ecology
Date : 2020
Volume : 44
Pages : 100907
Catégorie(s)
#CNRS #EcoGenO #Université de RennesRésumé
Cell identity relies on the cross-talk between genetics and epigenetics and their impact on gene expression. Oxidation of 5-methylcytosine (5mC) into 5-hydroxymethylcytosine (5hmC) is the first step of an active DNA demethylation process occurring mainly at enhancers and gene bodies and, as such, participates in processes governing cell identity in normal and pathological conditions. Although genetic alterations are well documented in multiple myeloma (MM), epigenetic alterations associated with this disease have not yet been thoroughly analyzed. To gain insight into the biology of MM, genome-wide 5hmC profiles were obtained and showed that regions enriched in this modified base overlap with MM enhancers and super enhancers and are close to highly expressed genes. Through the definition of a MM-specific 5hmC signature, we identified FAM72D as a poor prognostic gene located on 1q21, a region amplified in high risk myeloma. We further uncovered that FAM72D functions as part of the FOXM1 transcription factor network controlling cell proliferation and survival and we evidenced an increased sensitivity of cells expressing high levels of FOXM1 and FAM72 to epigenetic drugs targeting histone deacetylases and DNA methyltransferases.
Auteurs, date et publication :
Auteurs Fabrice Chatonnet , Amandine Pignarre , Aurélien A. Sérandour , Gersende Caron , Stéphane Avner , Nicolas Robert , Alboukadel Kassambara , Audrey Laurent , Maud Bizot , Xabier Agirre , Felipe Prosper , José I. Martin-Subero , Jérôme Moreaux , Thierry Fest , Gilles Salbert
Publication : Haematologica
Date : 2020
Volume : 105
Issue : 3
Pages : 774-783
Catégorie(s)
#CNRS #EcoGenO #Université de RennesRésumé
The sustainability of agricultural, forested and other managed or
natural ecosystems is critical for the future of mankind. However, the
services provided by these ecosystems are under threat due to climate
change, loss of biodiversity, and land use changes. In order to face the
challenges of preserving or improving ecosystems services and securing
food supply we need to understand and forecast how ecosystems will
respond to current and future changes. To help answer those questions
Ecotrons facilities are born. Such infrastructures provide sets of
confinement units for the manipulation of environmental conditions and
real-time measurement of ecological processes under controlled and
reproduceable conditions, bridging the gap between the complexity of in
natura studies and the simplicity of laboratory experiments.The European
Ecotron of Montpellier (www.ecotron.cnrs.fr) is an experimental research
infrastructure for the study of the impact of climate change on
ecosystem functioning and biodiversity. This infrastructure offers,
through calls open to the international community, three experimental
platforms at different scales. The Macrocosms platform is composed of
twelve 40 m3 units, each able to host 2-12 t lysimeters, with a 2-5
m² canopy area and a soil depth of up to 2 m. The Mesocosms one has
eighteen 2-4 m3 units, each able to host lysimeters of 0.4-1 m depth and
0.4-1 m² area. The Microcosms platform consists of growth chambers
(1 m height, 1 m² area) in which smaller units (with photosynthetic
plants, soils, insects, etc.) can be installed. Each experimental unit
of each platform allows to confine terrestrial ecosystems. This way,
environmental parameters such as temperature (-10 to +50 °C),
relative humidity (20-80 %), precipitation (sprinkler or drip) and
atmospheric CO2 concentration (200-1000 ppm) are strictly and
continuously controlled and recorded. But the uniqueness of the European
Ecotron of Montpellier lies on its ability to also continuously measure,
in each unit, net gas exchange (evapotranspiration, CO2 / CH4 / N2O net
fluxes) that occur in between the ecosystem studied and the atmosphere,
as well as CO2, H2O, N2O and O2 isotopologues. Those tools are powerful
and remarkable to access additional information about processus involved
in ecosystem functioning.The aim of this presentation is to describe the
Macrocosms and the Mesocosms platforms through examples of international
projects recently run in these platforms.
Auteurs, date et publication :
Auteurs Joana Sauze , Jacques Roy , Clément Piel , Damien Landais , Emmanuel S. Gritti , Olivier Ravel , Hélène Lemoine , Abdelaziz Faez , Sébastien Devidal , Alexandru Milcu
Date : 2020
Volume : 22
Pages : 8650
Catégorie(s)
#CNRS #Ecotron de MontpellierRésumé
Biogeochemical Cycles: Ecological Drivers and Environmental Impact is a collection of the latest information on the techniques and methods currently used in this field, focusing on biological and/or ecological effects of biogeochemical elemental cycles including carbon, nitrogen, major and trace elements, chemical weathering on multiple scales of nanometers to watersheds, and advances in technology of studying these processes.Volume highlights include:- Remote sensing and modeling techniques used to quantify changes in the ecosystem/s productivity, and microscopic techniques to estimate the extent of weathering - Novel isotopic techniques to assess changes in trace elemental cycles as influenced by the changing climate, and plant-mediated effect of climate change on major elemental cycles - Impact of climate change and other anthropogenic influences in agricultural and extreme (frontier) environmentsBiogeochemical Cycles: Ecological Drivers and Environmental Impact is a valuable resource for students, researchers and professionals in the field of biogeosciences, hydrology, ecology, earth and planetary surface processes, volcanology, petrology, geochemistry, mineralogy, soil science, agricultural science, climate change and environmental science.
Auteurs, date et publication :
Auteurs Katerina Dontsova , Zsuzsanna Balogh-Brunstad , Gaël Le Roux
Date : 2020
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENSRésumé
The determinants of intraspecific stoichiometric variation remain difficult to elucidate due to their multiple origins (e.g. genetic vs. environmental) and potential interactive effects. We evaluated whether two size-selected lines of medaka (Oryzias latipes) with contrasted life-history strategies (small- and large-breeder lines with slow growth and early maturity vs. fast growth and late maturity) differed in their organismal stoichiometry (percentage and ratios of carbon [C], nitrogen [N] and phosphorus [P]) in a mesocosm experiment. We also tested how size-selection interacted with environmental conditions (i.e. two levels of fish density and light intensity), body condition and sex. Results showed that large-breeder fish were significantly N-enriched compared to small-breeders, while the two size-selected lines did not differ in body P composition. Size-selection interacted with density – high density only affected small-breeders leading to decreasing %C and C: N – and with sex – large-breeder females had higher %C and C:N values than large-breeder males. Finally, C:P and N:P ratios increased with body condition due to decreasing %P. Overall, our results show that the ecological consequences of size-selective mortality extend to organismal stoichiometry and may, from there, change nutrient cycling and ecosystem functioning.
Auteurs, date et publication :
Auteurs Charlotte Evangelista , Beatriz Diaz Pauli , Leif Asbjørn Vøllestad , Eric Edeline
Publication : Science of The Total Environment
Date : 2020
Volume : 724
Pages : 138193