Auteurs, date et publication :
Auteurs CE Paine , Natalia Norden , Jérôme Chave , Pierre‐Michel Forget , Claire Fortunel , Kyle G Dexter , Christopher Baraloto
Publication : Ecology Letters
Date : 2025
Volume : 15
Issue : 1
Pages : 34-41
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Helianthemum is the largest, most widely distributed and most taxonomically complex genus of the Cistaceae. To examine the intrageneric phylogenetic relationships in Helianthemum, we used sequence data from plastid DNA (ndhF, psbA-trnH, trnLtrnF) and the nuclear ITS region. The ingroup consisted of 95 species and subspecies (2 subgenera, 10 sections) from throughout the range of Helianthemum, while the outgroup was composed of 30 species representing all the genera in the Cistaceae (Cistus Crocanthemum, Fumana, Halimium, Hudsonia, Lechea, Tuberaria) plus Anisoptera thurifera subsp. polyandra (Dipterocarpaceae). To infer phylogenetic relationships, we analysed three different matrices (cpDNA, nrDNA, cpDNA + nrDNA concatenated) using maximum likelihood and Bayesian inference, and performed molecular dating to estimate the ages of origin of the main clades using a Bayesian approach. The cpDNA + nrDNA concatenated dataset provided the highest Bayesian posterior probabilities and bootstrap support values, and the results supported the monophyly of the genus Helianthemum and its sister relationship to a clade consisting of all species of Cistus, Crocanthemum, Halimium, Hudsonia and Tuberaria. This result means that we did not retrieve the sister relationship between Helianthemum and Crocanthemum (plus Hudsonia) that could be expected according to previous published studies. Despite their different statistical support, the topology of the inner branches of all the consensus trees showed that Helianthemum is characterized by the emergence of three major clades in agreement with above-species taxonomy, although unresolved polytomies still remain towards the tips of the trees (species and subspecies). Clade I (mainly distributed in Mediterranean and alpine environments in European and western Asiatic mountain chains) fully coincided with subg. Plectolobum, whereas subg. Helianthemum was retrieved in clade II (arid and semi-arid environments from Macaronesia, the Mediterranean, subtropical northern Africa, Anatolia and central Asia) and clade III (Mediterranean ecosystems around the Mediterranean Basin). The burst of diversification during the Plio-Pleistocene detected in the three main clades of Helianthemum is concomitant with the Messinian salinity crisis, the onset of Mediterranean climatic conditions, and Quaternary glaciations, as found in many other groups of Mediterranean plants. Thus, the general lack of resolution in the trees can be attributed to rapid species diversification and events of reticulate evolution. A series of further taxonomic and evolutionary inferences can be drawn from our analyses: (i) no species occupied an early-diverging position with regard the rest of the species; (ii) a close relationship between H. caput-felis and subg. Plectolobum; (iii) an unexpected close relationship between H. squamatum/H. syriacum (and H. motae), H. lunulatum/ H. pomeridianum and among H. songaricum/H. antitauricum/H. germanicopolitanum; (iv) a close relationship between incertae sedis species and sect. Eriocarpum; and (v) the existence of a monophyletic lineage consisting of Canary Islands species formerly ascribed to sect. Argyrolepis or sect. Lavandulaceum within sect. Helianthemum.
Auteurs, date et publication :
Auteurs Abelardo Aparicio , Sara Martín-Hernanz , Clara Parejo-Farnés , Juan Arroyo , Sébastien Lavergne , Emine B. Yeşilyurt , Ming-Li Zhang , Encarnación Rubio , Rafael G. Albaladejo
Publication : Taxon
Date : 2017
Volume : 66
Issue : 4
Pages : 868-885
Catégorie(s)
#CNRS #Lautaret #UGARésumé
PREMISE Events of accelerated species diversification represent one of Earth's most celebrated evolutionary outcomes. Northern Andean high-elevation ecosystems, or páramos, host some plant lineages that have experienced the fastest diversification rates, likely triggered by ecological opportunities created by mountain uplifts, local climate shifts, and key trait innovations. However, the mechanisms behind rapid speciation into the new adaptive zone provided by these opportunities have long remained unclear. METHODS We address this issue by studying the Venezuelan clade of Espeletia, a species-rich group of páramo-endemics showing a dazzling ecological and morphological diversity. We performed several comparative analyses to study both lineage and trait diversification, using an updated molecular phylogeny of this plant group. RESULTS We showed that sets of either vegetative or reproductive traits have conjointly diversified in Espeletia along different vegetation belts, leading to adaptive syndromes. Diversification in vegetative traits occurred earlier than in reproductive ones. The rate of species and morphological diversification showed a tendency to slow down over time, probably due to diversity dependence. We also found that closely related species exhibit significantly more overlap in their geographic distributions than distantly related taxa, suggesting that most events of ecological divergence occurred at close geographic proximity within páramos. CONCLUSIONS These results provide compelling support for a scenario of small-scale ecological divergence along multiple ecological niche dimensions, possibly driven by competitive interactions between species, and acting sequentially over time in a leapfrog pattern.
Auteurs, date et publication :
Auteurs Charles Pouchon , Sébastien Lavergne , Ángel Fernández , Adriana Alberti , Serge Aubert , Jesús Mavárez
Publication : American Journal of Botany
Date : 2025
Volume : 108
Issue : 1
Pages : 113–128
Catégorie(s)
#CNRS #eDNA #Lautaret #UGARésumé
Abstract
The neotropical region ranks third in the number of termites and includes five different families. Of these, Termitidae is the most diverse and includes the species
Nasutitermes ephratae
, which is widespread in the neotropics. To date, only one study has been published about phylogeography in neotropical termites (
N. corniger
). Here, we explored the population genetic patterns of
N. ephratae
and also evaluated the phylogeographical processes involved in the evolutionary history of the species. We used the mitochondrial genes 16S rRNA and COII as molecular markers: these were sequenced for 128 samples of
N. ephratae
. We estimated the genetic diversity and divergence time as well as the demography and genetic structure. We also performed an ancestral area reconstruction and a haplotype network. The results showed high genetic variability, recent demographic expansion, and strong genetic structure. A dispersal route for the species, that occurred in both directions between South and Central America, was inferred. The results emphasize a temporary separation between the South and Central America populations that affected the origin of the current Central America populations. These populations were formed from different phylogeographic histories.
Auteurs, date et publication :
Auteurs Amanda de Faria Santos , Eliana Marques Cancello , Adriana Coletto Morales
Publication : Scientific Reports
Date : 2022
Volume : 12
Issue : 1
Pages : 11656
Catégorie(s)
#CNRS #FORET NouraguesRésumé
In the subsurface, water content, gas solubility, adsorption on minerals and chemical reactions control gas fluxes between soil and the atmosphere. Because these processes vary in intensity both in time and space, it is very challenging to quantify emissions, specifically when flux measurements are used for detection, identification or monitoring of a subsurface gas source. An experimental setup for gas percolation though soil column experiments under well-controlled conditions was developed and validated at the ECOTRON IleDeFrance research center. Its design included the effect of: i) watering/evaporation cycles, ii) barometric pressure, iii) injection pressure, iv) tracer behaviors and v) plant metabolism. To better understand subsurface processes controlling gas fluxes, we studied transport of multiple tracers across soil columns using long-term and high-resolution monitoring thanks to online low-flow mass-spectrometry. We injected tracer gases into columns containing different porous media, pure sillica sand and zeolite. This set-up allowed us to evaluate the relative contribution of diffusion, solubility and adsorption on various trace gases (SF6, noble gas including Xe). All the experimental data are discussed in conjonction with simulations using the NUFT unsaturated flow and transport code.
Auteurs, date et publication :
Auteurs Clément Alibert , Eric Pili , Pierre Barré , Charles Carrigan , Yunwei Sun , Hao Yue , Chollet Simon , Massol Florent
Date : 2025
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENSAuteurs, date et publication :
Auteurs Sylvain Haupert , Frédéric Sèbe , Jérôme Sueur
Publication : Methods in Ecology and Evolution
Date : 2022
Pages : 2041-210X.14020
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Volatile organic compounds (VOC) emitted from terrestrial vegetation constitute complex olfactory environments (odorscapes) and play major roles in the interactions between organisms. Insects for instance, extract essential cues for their reproduction from their olfactory environment. Plant VOC production and emission are affected by environmental parameters, such heat and drought. As part of ODORSCAPE, a research program funded by French ANR, the effects of combined elevated atmospheric ozone and CO2 concentrations on plant VOC production are studied, by assessing the stress-induced variations in the VOC emissions and in the corresponding biosynthesis pathways. Two crops representative of temperate agro-ecosystems, maize and poplar, are considered in this study. For CO2, 400 ppm or 800 ppm are applied to plants, starting at the germination step for maize and at the acclimatization step for poplar, while 30 ppb or 110 ppb of ozone are applied on fully developed plants, during 6h of the photoperiod, for 2 weeks. At the end of the four treatment combinations, photosynthetic and gas exchange parameters, and VOC emissions are measured and will be related to changes in the potential activity of key enzymes in the major VOC biosynthetic pathways (such as the lipoxygenase, mevalonate and methylerythritol phosphate pathways) and carbon fixing metabolisms (RubisCO and PEP carboxylase). This will allow us to evaluate the extent of photosynthetic carbon allocation toward VOC biosynthesis pathways in response to both elevated ozone and CO2. In addition, the stress-induced odorscapes will be tested for their effects on olfaction of herbivorous insects at gene, neural coding and behavior levels. Together, the results of this multidisciplinary project should reveal new aspects of the ecological consequences of climate change.
Auteurs, date et publication :
Auteurs Elodie Merlier , Matthieu Bagard , Ruben Puga-Freitas , Christophe Boissard , Luis Leitao , Anne Repellin , Amandine Hansart , Simon Chollet , Michael Staudt , Juliette Leymarie
Date : 2018
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENSAuteurs, date et publication :
Auteurs Bahar Shahnavaz , Lucie Zinger , Sébastien Lavergne , Philippe Choler , Roberto A. Geremia
Publication : Arctic, Antarctic, and Alpine Research
Date : 2025
Volume : 44
Issue : 2
Pages : 232-238
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Comparing the relationship between resource use and resource availability (i.e. the functional response, FR) between two predators can provide useful insights on their relative predatory impacts. For instance in invasion ecology, an increase in the predation pressure on local prey populations can be predicted from a significant difference in FR revealing a higher FR for the invasive predator compared to the native trophic analogue it may replace. In traditional FR experiments, the focal prey species is the only source of food. This may lead to misinterpretations with opportunistic omnivores that are able to cope with different resource availabilities in their natural environment, and whose predation rate may therefore be modulated by the presence of alternative resources. To address this question, we compared the FR of two freshwater gammarid species known to behave as opportunistic omnivores: the invasive “killer shrimp” Dikerogammarus villosus and the native Gammarus pulex, in a treatment with a focal prey species as the only food source (the water flea Daphnia magna) and in a treatment with the focal prey and an alternative food source (Carpinus betulus leaves). D. villosus showed a significantly higher FR than G. pulex with water fleas only and providing leaf litter suppressed this difference. The predatory impact of D. villosus might therefore be modulated by the relative availability of live prey compared to the alternative food sources. Increasing the realism of FR experiments through the inclusion of abundant and easily accessible alternative resources, like leaf litter for benthic invertebrates, should refine the predictions made from FR comparisons.
Auteurs, date et publication :
Auteurs Vincent Médoc , Laura Thuillier , Thierry Spataro
Publication : Biological Invasions
Date : 2018
Volume : 20
Issue : 5
Pages : 1307-1319
Catégorie(s)
#CNRS #ENS #PLANAQUARésumé
Stomatal conductance schemes that optimize with respect to photosynthetic and hydraulic functions have been proposed to address biases in land-surface model (LSM) simulations during drought. However, systematic evaluations of both optimality-based and alternative empirical formulations for coupling carbon and water fluxes are lacking. Here, we embed 12 empirical and optimization approaches within a LSM framework. We use theoretical model experiments to explore parameter identifiability and understand how model behaviors differ in response to abiotic changes. We also evaluate the models against leaf-level observations of gas-exchange and hydraulic variables, from xeric to wet forest/woody species spanning a mean annual precipitation range of 361–3,286 mm yr−1. We find that models differ in how easily parameterized they are, due to: (a) poorly constrained optimality criteria (i.e., resulting in multiple solutions), (b) low influence parameters, (c) sensitivities to environmental drivers. In both the idealized experiments and compared to observations, sensitivities to variability in environmental drivers do not agree among models. Marked differences arise in sensitivities to soil moisture (soil water potential) and vapor pressure deficit. For example, stomatal closure rates at high vapor pressure deficit range between −45% and +70% of those observed. Although over half the new generation of stomatal schemes perform to a similar standard compared to observations of leaf-gas exchange, two models do so through large biases in simulated leaf water potential (up to 11 MPa). Our results provide guidance for LSM development, by highlighting key areas in need for additional experimentation and theory, and by constraining currently viable stomatal hypotheses.
Auteurs, date et publication :
Auteurs Manon E. B. Sabot , Martin G. De Kauwe , Andy J. Pitman , Belinda E. Medlyn , David S. Ellsworth , Nicolas K. Martin-StPaul , Jin Wu , Brendan Choat , Jean-Marc Limousin , Patrick J. Mitchell , Alistair Rogers , Shawn P. Serbin
Publication : Journal of Advances in Modeling Earth Systems
Date : 2025
Volume : 14
Issue : 4
Pages : e2021MS002761