Résumé
1. Amazonian droughts are predicted to become increasingly frequent and intense, and the vulnerability of Amazonian trees has become increasingly documented. However, little is known about the physiological mechanisms and the diversity of drought tolerance of tropical trees due to the lack of quantitative measurements. 2. Leaf water potential at wilting or turgor loss point (πtlp) is a determinant of the tolerance of leaves to drought stress, and contributes to plant-level physiological drought tolerance. Recently, it has been demonstrated that leaf osmotic water potential at full hydration (π0) is tightly correlated with πtlp. Estimating πtlp from osmometer measurements of π0 is much faster than the standard pressure-volume curve approach of πtlp determination. We used this technique to estimate πtlp for 165 trees of 71 species, at three sites within forests in French Guiana. Our dataset represents a significant increase in available data for this trait for tropical tree species. 3. Tropical trees showed a wider range of drought tolerance than previously found in the literature, πtlp ranging from -1.4 to -3.2 MPa. This range likely corresponds in part to adaptation and acclimation to occasionally extreme droughts during the dry season. 4. Leaf-level drought tolerance varied across species, in agreement with the available published observations of species variation in drought-induced mortality. On average, species with a more negative πtlp (i.e., with greater leaf-level drought tolerance) occurred less frequently across the region than drought-sensitive species. 5. Across individuals, πtlp correlated positively but weakly with leaf toughness (R2=0.22, Accepted Article P=0.04) and leaf thickness (R2=0.03, P=0.03). No correlation was detected with other functional traits (leaf mass per area, leaf area, nitrogen or carbon concentrations, carbon isotope ratio, sapwood density or bark thickness). 6. The variability in πtlp among species indicates a potential for highly diverse species responses to drought within given forest communities. Given the weak correlations between πtlp and traditionally measured plant functional traits, vegetation models seeking to predict forest response to drought should integrate improved quantification of comparative drought tolerance among tree species
Auteurs, date et publication :
Auteurs Isabelle Maréchaux , Megan K. Bartlett , Lawren Sack , Christopher Baraloto , Julien Engel , Emilie Joetzjer , Jérôme Chave , Kaoru Kitajima
Publication : Functional Ecology
Date : 2015
Volume : 29
Issue : 10
Pages : 1268–1277
Catégorie(s)
#ANR-Citation #CIRAD #CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs Marga Born , Frans Bongers , Erik H. Poelman , Frank J. Sterck
Publication : Phyllomedusa: Journal of Herpetology
Date : 2010
Volume : 9
Issue : 1
Pages : 37-52
Catégorie(s)
#CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs Isabelle Maréchaux , Damien Bonal , Megan K Bartlett , Benoît Burban , Sabrina Coste , Elodie A Courtois , Maguy Dulormne , Jean‐Yves Goret , Eléonore Mira , Ariane Mirabel
Publication : Functional Ecology
Date : 2025
Volume : 32
Issue : 10
Pages : 2285-2297
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Next-generation sequencing technologies have opened a new era of research in population genetics. Following these new sequencing opportunities, the use of restriction enzyme-based genotyping techniques, such as restriction site-associated DNA sequencing (RAD-seq) or double-digest RAD-sequencing (ddRAD-seq), has dramatically increased in the last decade. From DNA sampling to SNP calling, the laboratory and bioinformatic parameters of enzyme-based techniques have been investigated in the literature. However, the impact of those parameters on downstream analyses and biological results remains less documented. In this study, we investigated the effects of sevral pre- and post-sequencing settings on ddRAD-seq results for two biological systems: a complex of butterfly species (Coenonympha sp.) and several populations of common beech (Fagus sylvatica). Our results suggest that pre-sequencing parameters (i.e., DNA quantity, number of PCR cycles during library preparation) have a significant impact on the number of recovered reads and SNPs, on the number of unique alleles and on individual heterozygosity. In the same way, we found that post-sequencing settings (i.e., clustering and minimum coverage thresholds) influenced loci reconstruction (e.g., number of loci, mean coverage) and SNP calling (e.g., number of SNPs; heterozygosity) but had only a marginal impact on downstream analyses (e.g., measure of genetic differentiation, estimation of individual admixture, and demographic inferences). In addition, replication analyses confirmed the reproducibility of the ddRAD-seq procedure. Overall, this study assesses the degree of sensitivity of ddRAD-seq data to pre- and post-sequencing protocols, and illustrates its robustness when studying population genetics.
Auteurs, date et publication :
Auteurs Tristan Cumer , Charles Pouchon , Frédéric Boyer , Glenn Yannic , Delphine Rioux , Aurélie Bonin , Thibaut Capblancq
Publication : Molecular Genetics and Genomics
Date : 2025
Volume : 296
Issue : 2
Pages : 457–471
Catégorie(s)
#CNRS #eDNARésumé
Pellet counts are widely used to monitor ungulates but rely on the assumption that pellets of different species are correctly identified in the field. Recent studies question this assumption using DNA barcoding techniques to check field identification rates. For Europe, which is undergoing a rapid shift towards more diverse ungulate assemblages, such an assessment is still missing. Using DNA barcoding on 3889 fecal samples from nine ungulate species in four European countries, we found average field misidentification rates varied from 0.6% for horse (Equus ferus) to 41.1% for roe deer (Capreolus capreolus). Most identification errors occurred between similar-sized species from the same taxonomic family. For a subset of samples from Sweden, we looked at the effect of dung morphometry, observer experience, and season on species identification success. Dung morphometry clearly distinguished moose (Alces alces) but not red (Cervus elaphus), roe, and fallow deer (Dama dama). Experienced observers performed better than novices for red and fallow deer although still making significant identification errors (26% and 17% incorrectly identified). Identification success was higher during spring and winter (x¯$$ overline{x} $$= 86%) than summer and autumn (x¯$$ overline{x} $$= 74%). We question pellet counts as an accurate monitoring tool where similar-sized species coexist and monitoring relates to the whole community. For this increasingly common situation across Europe, DNA testing or camera traps may be a better alternative. Pellet counts remain useful where only few species with clearly different dung morphology coexist (e.g., moose and roe deer) or when focused on species with distinctive dung morphology (e.g., moose).
Auteurs, date et publication :
Auteurs Robert Spitzer , Marcin Churski , Annika Felton , Marco Heurich , Dries P. J. Kuijper , Marietjie Landman , Esther Rodriguez , Navinder J. Singh , Pierre Taberlet , Suzanne T. S. van Beeck Calkoen , Fredrik Widemo , Joris P. G. M. Cromsigt
Publication : European Journal of Wildlife Research
Date : 2019
Volume : 65
Issue : 2
Pages : 28
Catégorie(s)
#CNRS #eDNARésumé
Phenolic compounds play important ecological roles in alpine plants such as offering efficient UV protection at high level of incident sunlight. Methods to study those compounds are limited, as they require sophisticated analytical tools and are time-consuming. An alternative and portable device—Dualex©—has been recently developed to estimate the plant epidermal flavonoids by fluorescence sensing. Here, we assessed if the Dualex device accurately estimates the phenolic contents of three alpine plant species along an elevational gradient and be an alternative to the commonly used chemical methods. We characterized their leaf epidermal absorbance measured by the Dualex device, total phenol content assessed by the Folin–Ciocalteu assay and total flavonoid content estimated by high-performance liquid chromatography. The results showed that leaf epidermal absorbance was slightly positively correlated to total phenols for Rhododendron ferrugineum and Dryas octopetala, but not for Vaccinium myrtillus and to total flavonoids for the first species, but not for the two others. The leaf epidermal absorbance estimated by the Dualex device is not an accurate and universal predictor of total phenols or total flavonoid contents for alpine plant species. The limitations of this optical method could be mainly explained by the high intraspecific variability of plant chemical composition in heterogeneous environmental conditions met in alpine areas. We thus recommend a cautious use of this device to avoid misinterpretations.
Auteurs, date et publication :
Auteurs Tiphaine Lefebvre , Annie Millery-Vigues , Christiane Gallet
Publication : Alpine Botany
Date : 2016
Volume : 126
Issue : 2
Pages : 177-185
Catégorie(s)
#CNRS #Lautaret #UGAAuteurs, date et publication :
Auteurs Irene Mendoza , Gabrielle Martin , Adeline Caubere , Patrick Châtelet , Isabelle Hardy , Sylvie Jouard , Pierre-Michel Forget
Publication : Journal of Tropical Ecology
Date : 2025
Volume : 31
Issue : 6
Pages : 553-556
Catégorie(s)
#CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs L. Jacquin , Q. Mori , V. MéDoc
Publication : Parasitology
Date : 2025
Volume : 140
Issue : 10
Pages : 1310-1315
Catégorie(s)
#CNRS #ENS #PLANAQUARésumé
Highly differentiated mature spermatozoa carry not only genetic but also epigenetic information that is to be transmitted to the embryo. DNA methylation is one epigenetic actor associated with sperm nucleus compaction, gene silencing, and prepatterning of embryonic gene expression. Therefore, the stability of this mark toward reproductive biotechnologies is a major issue in animal production. The present work explored the impact of hormonal induction of spermiation and sperm cryopreservation in two cyprinids, the goldfish (Carassius auratus) and the zebrafish (Danio rerio), using LUminometric Methylation Assay (LUMA). We showed that while goldfish hormonal treatment did increase sperm production, it did not alter global DNA methylation of spermatozoa. Different sperm samples repeatedly collected from the same males for 2 months also showed the same global DNA methylation level. Similarly, global DNA methylation was not affected after cryopreservation of goldfish spermatozoa with methanol, whereas less efficient cryoprotectants (dimethylsulfoxide and 1,2-propanediol) decreased DNA methylation. In contrast, cryopreservation of zebrafish spermatozoa with methanol induced a slight, but significant, increase in global DNA methylation. In the less compact nuclei, that is, goldfish fin somatic cells, cryopreservation did not change global DNA methylation regardless of the choice of cryoprotectant. To conclude, global DNA methylation is a robust parameter with respect to biotechnologies such as hormonal induction of spermiation and sperm cryopreservation, but it can be altered when the best sperm manipulation conditions are not met.
Auteurs, date et publication :
Auteurs Alexandra Depincé , Anne Gabory , Katarzyna Dziewulska , Pierre-Yves Le Bail , Hélène Jammes , Catherine Labbé
Publication : Molecular Reproduction and Development
Date : 2025
Volume : 87
Issue : 1
Pages : 124-134
Catégorie(s)
#CNRS #EcoGenO #Université de RennesAuteurs, date et publication :
Auteurs Elodie A Courtois , CE Timothy Paine , Pierre-Alain Blandinieres , Didier Stien , Jean-Marie Bessiere , Emeline Houel , Christopher Baraloto , Jerome Chave
Publication : Journal of chemical ecology
Date : 2025
Volume : 35
Issue : 11
Pages : 1349-1362