Résumé
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
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 #UGAAuteurs, 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
Abstract. This paper examines the ability of optical reflectance data assimilation to improve snow depth and snow water equivalent simulations from a chain of models with the SAFRAN meteorological model driving the detailed multilayer snowpack model Crocus now including a two-stream radiative transfer model for snow, TARTES. The direct use of reflectance data, allowed by TARTES, instead of higher level snow products, mitigates uncertainties due to commonly used retrieval algorithms.Data assimilation is performed with an ensemble-based method, the Sequential Importance Resampling Particle filter, to represent simulation uncertainties. In snowpack modeling, uncertainties of simulations are primarily assigned to meteorological forcings. Here, a method of stochastic perturbation based on an autoregressive model is implemented to explicitly simulate the consequences of these uncertainties on the snowpack estimates.Through twin experiments, the assimilation of synthetic spectral reflectances matching the MODerate resolution Imaging Spectroradiometer (MODIS) spectral bands is examined over five seasons at the Col du Lautaret, located in the French Alps. Overall, the assimilation of MODIS-like data reduces by 45% the root mean square errors (RMSE) on snow depth and snow water equivalent. At this study site, the lack of MODIS data on cloudy days does not affect the assimilation performance significantly. The combined assimilation of MODIS-like reflectances and a few snow depth measurements throughout the 2010/2011 season further reduces RMSEs by roughly 70%. This work suggests that the assimilation of optical reflectances has the potential to become an essential component of spatialized snowpack simulation and forecast systems. The assimilation of real MODIS data will be investigated in future works.
Auteurs, date et publication :
Auteurs Luc Charrois , Emmanuel Cosme , Marie Dumont , Matthieu Lafaysse , Samuel Morin , Quentin Libois , Ghislain Picard
Publication : The Cryosphere
Date : 2016
Volume : 10
Issue : 3
Pages : 1021-1038
Catégorie(s)
#CNRS #Lautaret #UGAAuteurs, date et publication :
Auteurs Jean-Pierre Dedieu , Bradley Carlson , Sylvain Bigot , Pascal Sirguey , Vincent Vionnet , Philippe Choler
Publication : Remote Sensing
Date : 2016
Volume : 8
Issue : 6
Pages : 481
Catégorie(s)
#CNRS #Lautaret #UGAAuteurs, date et publication :
Auteurs Cécile H. Albert , Francesco de Bello , Isabelle Boulangeat , Gilles Pellet , Sandra Lavorel , Wilfried Thuiller
Publication : Oikos
Date : 2025
Volume : 121
Issue : 1
Pages : 116-126
Catégorie(s)
#CNRS #Lautaret #UGARésumé
We combined imagery from multiple sources (MODIS, Landsat-5, 7, 8) with land cover data to test for long-term (1984–2015) greening or browning trends of vegetation in a temperate alpine area, the Ecrins National Park, in the context of recent climate change and domestic grazing practices. We showed that over half (56%) of the Ecrins National Park displayed significant increases in peak normalized difference vegetation index (NDVImax) over the last 16 years (2000–2015). Importantly, the highest proportional increases in NDVImax occurred in rocky habitats at high elevations (> 2500 m a.s.l.). While spatial agreement in the direction of change in NDVImax as detected by MODIS and Landsat was high (76% overlap), correlations between log-response ratio values were of moderate strength (approx. 0.3). In the context of above treeline habitats, we found that proportional increases in NDVImax were higher between 1984 and 2000 than between 2000 and 2015, suggesting a slowing of greening dynamics during the recent decade. The timing of accelerated greening prior to 2000 coincided with a pronounced increase in the amount of snow-free growing degree-days that occurred during the 1980s and 1990s. In the case of grasslands and low-shrub habitats, we did not find evidence for a negative effect of grazing on greening trends, possibly due to the low grazing intensity typically found in the study area. We propose that the emergence of a longer and warmer growing season enabled high-elevation plant communities to produce more biomass, and also allowed for plant colonization of habitats previously characterized by long-lasting snow cover. Increasing plant productivity in an alpine context has potential implications for biodiversity trajectories and for ecosystem services in mountain landscapes. The presented evidence for long-term greening trends in a representative region of the European Alps provides the basis for further research on mechanisms of greening in alpine landscapes.
Auteurs, date et publication :
Auteurs Bradley Z Carlson , Monica C Corona , Cédric Dentant , Richard Bonet , Wilfried Thuiller , Philippe Choler
Publication : Environmental Research Letters
Date : 2017
Volume : 12
Issue : 11
Pages : 114006
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Bruley, E., B. Locatelli, and S. Lavorel. 2021. Nature’s contributions to people: coproducing quality of life from multifunctional landscapes. Ecology and Society 26(1):12. https://doi.org/10.5751/ES-12031-260112
Auteurs, date et publication :
Auteurs Enora Bruley , Bruno Locatelli , Sandra Lavorel
Publication : Ecology and Society
Date : 2021
Volume : 26
Issue : 1
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Reintroductions inherently involve a small number of founders leading reintroduced populations to be prone to genetic drift and, consequently, to inbreeding depression. Assessing the origins as the genetic diversity and structure of reintroduced populations compared to native populations are thus crucial to foresee their future. Here, we aim to clarify the origins of the Alpine marmots reintroduced in the Pyrenees and to evaluate the genetic consequences of this reintroduction after almost 30 years without monitoring. We search for the origins and compare the genetic structure and the genetic variability of three reintroduced Pyrenean and eight native Alpine populations using pairwise genetic distances, Bayesian clustering method and multivariate analyses. Our results reveal that the Alpine marmots reintroduced in the Pyrenees originated both from the Northern and the Southern Alps, and that, despite these multiple origins, none of the current Pyrenean marmots are admixed. The reintroduction led to a strong genetic differentiation and to a decrease in genetic diversity. This pattern likely results from the small number of founders and the low dispersal capacities of Alpine marmots and thus, highlight the necessity to consider both genetic characteristics and natural history when reintroducing a species.
Auteurs, date et publication :
Auteurs Coraline Bichet , Sandrine Sauzet , Laetitia Averty , Pierre Dupont , Mariona Ferrandiz-Rovira , Caterina Ferrari , Irene Figueroa , Marion Tafani , Célia Rézouki , Bernat C. López , Aurélie Cohas
Publication : Conservation Genetics
Date : 2016
Volume : 17
Issue : 5
Pages : 1157-1169
Catégorie(s)
#CNRS #Lautaret #UGARésumé
Mountain social-ecological systems (SES) supply important ecosystem services that are threatened by climate change. In mountain SES there is a paradox between high community capacity to cope with extremes, and governance structures and processes that constrain that capacity from being realised. Climate adaptation that maintains livelihoods and supply of ecosystem services can catalyse this innate adaptive capacity if new adaptive governance arrangements can be created. Using the French Alps as a case study, we outline a participative framework for transformative adaptation that links adaptive capacity and governance to provide social innovation and ecosystem-based adaptation solutions for mountain SES. Grassland management was the main entry point for adaptation: bundles of adaptation services supplied by the landscape mosaic of biodiverse grassland types can maintain agricultural production and tourism and facilitate income diversification. Deliberate management for core adaptation services like resilient fodder production, erosion control, shade or aesthetic value generates co-benefits for future transformation ability. People activate bundles of adaptation services along adaptation pathways and realise benefits via co-production with other forms of capital including traditional knowledge or social networks. Common and distinctive adaptation services in each pathway create options for transformation if barriers from interactions between values and rules across scales can be overcome. For example conserving mown terraces which is a critical adaptation nexus reflects a complex interplay of values, markets and governance instruments from local to European scales. We conclude that increasing stakeholders capacity to mobilise adaptation services is critical for empowering them to implement adaptation to global change.
Auteurs, date et publication :
Auteurs Sandra Lavorel , Matthew J. Colloff , Bruno Locatelli , Russell Gorddard , Suzanne M. Prober , Marine Gabillet , Caroline Devaux , Denis Laforgue , Véronique Peyrache-Gadeau
Publication : Environmental Science & Policy
Date : 2025
Volume : 92
Pages : 87-97