The Labex CEBA opens an annual competitive call for proposals to encourage innovative research on biodiversity in French Guiana. Projects are evaluated by the Scientific Board and by external referees.
In 2025, CEBA will fund 13 projects, summarised below.
CEM2IX – Chemotaxonomic Exploration of the Macro and MIcromycetes Xylariales of French Guiana.
PIs: Véronique Eparvier (ICSN, Gif sur Yvette, France)
Abstract: Fungi are ubiquitous in all environments, playing an essential role in ecosystem processes thanks to their ability to produce specialized metabolites used for communication and defense. These metabolites are of great interest for their potential applications in medicine, agriculture and biotechnology. While the identification of fungi has traditionally relied on morphological features and phylogenetic markers such as ITS sequences, chemotaxonomy, which classifies organisms according to their metabolic profiles, remains little exploited despite its potential to improve fungal classification. Modern analytical tools, such as molecular networking generated from LC-MS/MS data, now make it possible to explore the chemical diversity of fungi on a large scale.
This project proposes a pioneering study of the chemotaxonomy of micro and macromycetes collected in French Guiana, a region rich in fungi biodiversity. The aim is to characterize the metabolic profiles of fungi, particularly those of the Xylariales order, to identify reliable chemical markers, reduce dependence on ITS and discover new bioactive metabolites. The methodology is based on the use of LC-MS/MS analyses and the visualization of metabolic profiles via molecular networks.
Expected results include the identification of specific chemomarkers, the discovery of new biomarkers compounds such as chordapyrones, a better understanding of metabolic diversity as a function of environmental and developmental factors, and advances in the taxonomic classification of fungi.
This one-year project promises to make significant contributions to chemotaxonomy, chemical ecology and natural products research, while enhancing the little-studied fungi (in our case endophytes) of French Guiana.
© ICSN, Photos of Xylariales specimens collected in French Guiana
CHEMORES – Interdisciplinary Analysis of Resins in Pre-Columbian Hafted Axes from French Guiana.
PIs: Yannick Estevez (ECOFOG, Kourou, Guyane Française)
Abstract: Pre-Columbian stone axe heads are frequently found in French Guiana. A very small proportion of them have a handle or remains of substance used to join the stone head to the handle. There are two types of hafting: by juxtaposition and by inclusion. These types seems to be a strong chronological marker. The juxtaposition hafting is mostly attested for axe heads with notches and grooved heel, eared axe heads and some grooved axe heads are mostly hafted by juxtaposition. This type of hafting is attested until the 10th century AD. Thereafter, the second type of hafting, by inclusion, seems to be exclusive until recently, as witnessed by the latest production of axes from Guyana1. All these axes, from the early Ceramic age to the present day, feature an adhesive substance in the hafting system. The nature of these resins has never been studied in depth (1). One of the hypotheses would be to verify whether the nature of the resin is also a chronocultural factor: do the exudates selected change over time or according to human groups?
The aim of this project is to analyze the resins used in the hafting of pre-Columbian axes in French Guian
a, using an interdisciplinary approach combining archaeology, analytical chemistry and ethnography.
The main objectives are: 1. Identify the types of resins used and their botanical sources. 2. Promote Guiana’s archaeological heritage to the public and local actors. The project uses advanced analytical techniques (FTIR, GC-MS and LC-MS) and collaborations with local partners to disseminate knowledge more widely.
© Lolita Rousseau, Inrap NAOM
EthnoT@xa – Using ethnotaxonomy and local languages to foster participatory inventory of French Guyanese local flora through app-based environmental education.
PIs: Guillaume Odonne (LEEISA, Cayenne, Guyane Française)
Abstract : French Guiana is both a biodiversity hotspot and a culturally diverse region inhabited by various Indigenous peoples, Maroons, Creoles, Metropolitan French, and recent migrant groups. Since the 1970s, researchers have documented the diverse relationships between these groups and the region’s biological diversity, termed as biocultural heritage. By improving the restitution of ethnobiological research carried out in French Guiana to the communities involved, this project contributes to the application of the Nagoya protocol and international recommendations in ethnobiology.
Hence, the EthnoT@xa project has three main objectives: compiling and making available locally (already published) ethnotaxonomic data for the flora of French Guiana; increasing botanical data collection through participatory use of Pl@ntNet in local languages; and reconnecting French Guianese youth with their local environment. The project involves reinforcing a taxonomic reference system, gathering local plant names, translating Pl@ntNet interfaces into regional languages, integrating local names into the Pl@ntNet repository, and training environmental mediators to utilize the app for educational purposes.
The project thus aims to complete a checklist of vernacular names for non-tree species, contributing significantly to biocultural heritage, ethnobotany, and botany. Additionally, it seeks to increase interest in plant diversity and local plant names among French Guianese pupils and scholars. Through educational activities using Pl@ntNet, the project anticipates an increase in the app’s users and plant observations for French Guiana, enriching global biodiversity repositories and participatory science initiatives. Overall, the project aims to preserve biocultural heritage, enhance environmental education, and contribute to biodiversity conservation efforts.
© Guillaume Odonne
EVOPATH – EVOlutionary PATHway toward gigantism in Neotropical beetles.
PIs: Fabien Condamine (ISEM, Montpellier, France)
Abstract : Gigantism is a striking but poorly understood evolutionary phenomenon characterized by extreme body size that can influence ecological interactions, life history traits, and physiological constraints. While extensively studied in vertebrates, the genetic and evolutionary drivers of gigantism in insects remain largely unexplored with genomic data within a phylogenetic framework. Beetles, with their immense diversity and broad ecological adaptations, provide a unique opportunity to study this phenomenon. The EVOPATH project aims to unravel the evolution of extreme body size in the beetle tribe Macrodontiini, in particular within the genus Macrodontia, which exhibits significant size variation (3-17 cm, including the third largest beetle in the world). Compared to other beetle clade, this group represents an ideal model to study the genomic and evolutionary forces that shape gigantism.
To achieve this, EVOPATH will integrate high-quality whole-genome data for all Macrodontiini species with a robust phylogenetic framework. The project has four main goals: (1) to generate a reference genome for Macrodontia, (2) to sequence whole genomes for all 18 Macrodontiini species, (3) to reconstruct a robust phylogeny using thousands of orthologous genes, and (4) to identify genomic signatures associated with the evolution of gigantism. Fieldwork in French Guiana will provide fresh samples, and most species have already been sampled but the missing species will be obtained from museum collections in Paris. Using state-of-the-art sequencing and genomic analyses, we will examine molecular evolutionary patterns to determine whether gigantism arose through shared genetic pathways or independent adaptations. By providing the first phylogenomic framework for Macrodontiini and identifying genes under selection in giant lineages, EVOPATH will provide key insights into the evolutionary constraints and adaptations underlying extreme body size. This research will not only deepen our understanding of insect gigantism, but also contribute broadly to evolutionary biology and genomics in Neotropical insects.
© ISEM
ForDec – Is FORest DECline in the western forests of French Guiana caused by soil water conditions?
PIs: Damien Bonal (SILVA, Nancy, France)
Abstract : With climate change, the probability of major forest decline caused by extreme climate conditions or pathogen and/or insect attacks is increasing. In French Guiana, no major forest declines unrelated to human activities have been observed so far. Yet, in 2022, unusual large patches of forest mortality were observed at several sites (and/or habitats) in western French Guiana.
Their origin remains unknown and the objective of the ForDec project is to understand whether recent unusual soil water conditions (either drought, or excess of water leading to anoxia) influenced tree functioning and led to greater tree mortality in different habitats and sites. We will use a stable isotope approach (carbon isotope composition, δ13C) in the xylem wood of both healthy and recently-dying trees across a large range of species at the Réserve Naturelle Nationale de la Trinité to identify whether soil water conditions were the main cause of the observed decline. Micro wood cores (2-mm diameter, 2-cm length) will be collected for a total of 200 trees in the Guyafor inventory plot or in newly set-up inventory plots by ONF in two distinct habitats (up-hill and bottomland).
The ForDec project addresses key objectives of Labex CEBA2 (WP4 – Biodiversity response to global change) by quantifying biodiversity response (both functional and taxonomic) to global change, including climatic and soil factors. This project promises to provide unique insights into how neotropical ecosystems may suffer (forest decline) and adapt to climate change. It involves both functional ecology scientists (UMR SILVA, UMR ECOFOG, ONF RDI), forest managers (ONF), and forest curators (RNNT).
© Olivier Bruneaux, ONF Guyane
INTRAIT – Influence of intraspecific trait variability on the functional diversity of fish communities in French Guiana.
PIs: Aurèle Toussaint
Abstract: The INTRAIT project aims to quantify the influence of intraspecific trait variability (ITV) on the functional structure of freshwater fish communities in tropical ecosystems, focusing on six rivers in French Guiana. While trait-based ecology has traditionally emphasized interspecific variation (differences between species), growing evidence suggests that ITV plays a critical role in shaping community assembly, ecosystem functioning, and species adaptability. This project seeks to address key gaps in our understanding of how phenotypic plasticity and trait variability within species influence biodiversity patterns in tropical freshwater ecosystems. To achieve this, we will measure morphological traits from multiple individuals per species. Fieldwork will employ standardized sampling protocols (nets, cast nets, dip nets, and traps) to capture a representative range of species across diverse habitats. Collaborations with local stakeholders and ongoing monitoring programs under the European Water Framework Directive (WFD) will enhance sampling efficiency and data quality. The project is structured around three key objectives: 1. Quantify ITV in fish species and compare it to interspecific variation, investigating whether ITV follows patterns of phylogenetic conservatism or is influenced by ecological strategies. 2. Evaluate the influence of ITV on functional diversity, testing whether it increases functional redundancy (species sharing similar roles) or enhances functional uniqueness (distinct ecological niches). 3. Compare ITV across sites, assessing how species richness and anthropogenic disturbances (e.g., habitat degradation) affect trait variability. We hypothesize that species-rich sites exhibit lower ITV due to niche saturation, while human disturbances reduce ITV by selecting against extreme trait values. The outcomes will provide novel insights into the ecological and evolutionary significance of ITV, offering new frameworks for trait-based ecology, biodiversity conservation, and ecosystem management. The project will also deliver the first dataset of intraspecific morphological trait variability in tropical freshwater fish, made openly accessible to support future research in macroecology and conservation biology.
MAHOMIPS – Genetic delimitation and characterization of maho tree species (Eschweilera, Lecythidaceae) using Molecular Inversion Probes (MIPs).
PIs: Myriam Heuertz, Niklas Tysklind (BIOGECO, Bordeaux, France)
Abstract: French Guiana’s forests, located in the Guiana Shield in northeastern South America, are one of the world’s oldest and most biodiverse tropical rainforest ecosystems. Timber production in French Guiana (FG) mostly relies on extractive timber harvesting with ongoing significant production increases to meet a growing demand. To sustain timber production, diversification of timber species for selective logging is crucial, but unambiguous identification of species is needed beforehand.
The family Lecythidaceae, commonly known as the Brazil nut family, plays a significant role in the ecology and biodiversity of FG’s rainforests. Within the genus Eschweilera, which is the most diverse and widely distributed genus in Lecythidaceae, phylogenetic relationships are complex and have been the subject of extensive research. The Parvifolia clade has recently been suggested as the new circumscription of Eschweilera sensu stricto, which we adopt in this proposal. Several Eschweilera species, collectively known as maho noir, have high potential for timber production. However, forest plots can contain more than a dozen sympatric Eschweilera species, and their botanical identification may be subject to confusion. Species confusion hampers the consistency of wood technological properties in extracted timber, and can threaten rare Eschweilera species such as E. squamata, IUCN category endangered.
The aim of MAHOMIPS is to genetically delimit Eschweilera (maho) species, characterise their distribution, genetic structure and genetic diversity and its co-variation with environmental variables, locally and at the regional scale in FG. For this, we will apply a genetic marker approach based on Molecular Inversion Probes (MIPS) that is highly scalable and suitable to genotype both large marker numbers (thousands) in high numbers of samples (hundreds to thousands). We will produce a MIPS based genetic dataset using ca. 1150 available samples of Eschweilera sampled at the local or regional scales in French Guiana to reach the specific objectives O1, a robust genetic species delimitation in Eschweilera and characterization of their distribution and genetic diversity; and O2, the characterization of environmental drivers of adaptation using genotype-environment associations in Eschweilera species. The project contributes to an ongoing Master2 thesis and its results will be useful for the subsequent development of simple in-forest species discrimination traits in the bark or shallow trunk slash with the help of AI-based approaches.
© BIOGECO
MULTIIMPACT – Characterization of PfMDR1S1034 diversity in Plasmodium falciparum from French Guiana and its implication in antimalarial drug resistance.
PIs: Célia Florimond (IPG, Cayenne, Guyane Française)
Abstract: Plasmodium falciparum is responsible for the deadliest cases of malaria worldwide, is mainly endemic in Africa, Southeast Asia and South America. Throughout the years, the specificity of the vector species, the different treatments policies and the transmission levels have shaped the geographic diversity in genotype frequencies worldwide. Since 2001, Artemisinin-Combination Therapies (ACTs) are recommended by the WHO to treat malaria. Over time, distinct occurrences of drug resistances associated with therapeutic failures jeopardized the fight against malaria worldwide and put a threat on the global goal of malaria elimination.
Studies related to these resistances mainly put in highlight the presence of genetic modifications on key factors involved in the transport or metabolism of the drugs. As such, the transporter PfMDR1 (Plasmodium falciparum Multi-Drug Resistance 1) has been associated with several cases of drug resistances. Genetic modifications involve gene copy number variation (CNV) or single nucleotide polymorphism (SNP).
In this context, genetic surveillance on isolates collected in French Guiana revealed that 62% (n=380/616) carried a polymorphism at position 1034. The purpose of this project is to characterize this genetic modification through genome editing experiments of local strains and assess its potential involvement in antimalarial drug resistance using chemosensitivity assays.
© Institut Pasteur de Guyane
NIRVANA – Near Infra-Red Spectroscopy ANAlysis for the improvement of identification and discrimination systems of living tree species in the field in the Amazon rainforest.
PIs: Daniela Florez. (ECOFOG, Kourou, Guyane Française)
Abstract : For botanists, reliable identification of tree species in rainforest is not a trivial task due to the high similarity of morphological traits among species and the rarity of fertile structures (flowers and fruits). In this rich ecosystem, deploying rapid, cost-effective and non-destructive analysis to improve forest inventories is equivalent to reaching NIRVANA. The integration of Near-Infrared Spectroscopy (NIRS) in forestry applications has successfully demonstrated the ability of this technology to identify and discriminate plant species from the spectral patterns of their tissues. The complex spectral responses captured by NIRS are based on the chemical composition and structure of each tissue and can be interpreted as “chemical fingerprints”. Trough (1) the development of a discrimination-dedicated spectral database of leaf (fresh and dry) and bark tissue (rhytidome and secondary phloem); (2) the determination of the best suited chemometric methods for species discrimination, including the combination of spectral information from different organs; (3) and the development of standardized protocols, the NIRVANA project aims to assess the ability of NIRS to discriminate and predict high value potential tree species in the field pertaining to Lecythidaceae, Burseraceae and Lauraceae families. NIRVANA will yield novel insights into the spectral diversity of tropical trees species from the Amazon and exploit spectral pattern differences to develop the first predictive models for species field identification in French Guiana.
© Emma Kieny
SHAREPOINT – Social organization and parasite sharing among rainforest understory birds.
PIs: Christophe Thebaud (CRBE, Toulouse, France), Javier Perez-Tris (Universidad Computense de Madrid)
Abstract : Gregarious animals are expected to be more exposed to parasite infections than solitary animals, because living in groups brings susceptible hosts into closer contact and groups tend to attract more parasite vectors. Comparative studies have provided much evidence for the link between social behaviour and parasite prevalence, but the possibility that social networks fine-tune parasite sharing patterns at the community level has received less attention. If groups act as parasite transmission hubs, members of the same group may have more similar parasites, and thus suffer more similar parasite impacts, than they share with members of other groups. We will investigate how animal interspecific sociality drives parasite exchange at the community level using the antbirds of Nouragues as a model system. Antbirds form mixed-species flocks with a very stable social structure and territorial spacing, including traditional roosting sites where flock mates may be more exposed to parasite exchange through vector bites and close contact. These features should promote the emergence of socially driven parasite transmission patterns among these species, which include the most prominent parasite reservoirs in the understory bird community. Drawing on data from decades of monitoring antbird territories in Nouragues, our own data on vector-borne avian malaria parasites and faecal-oral transmitted viruses obtained during 2015-2020, and new data to be obtained in this project, we will test whether parasites and parasite impacts on body condition are more similar among flock mates than among members of different flocks. In addition, our repeated sampling will allow us to separate social from spatial effects: we expect territory location to explain overall parasite prevalence (due to microhabitat drivers of transmission rate), but parasite turnover should blur over the years the spatial patterns of parasite distribution driven by host sociality within years. This project, which bridges the disciplines of animal behaviour and disease ecology, will help us understand how animal social networks set the stage for disease spread and the costs of parasitism in natural communities, while contributing to the long-term monitoring of ecological processes and wildlife health in the rainforest.
© Christophe Thebaud
SOHO – Characterizing fine-scale SOil spatial Heterogeneity to understand Observed variability in co-occurring tree functioning.
PIs: Isabelle Maréchaux et Bertille Loiseau (AMAP, Montpellier, France)
Abstract : Tropical forests play a disproportionate role in the global carbon cycles. However, the seasonal variability in carbon fluxes between tropical rainforests and atmosphere is still poorly understood. Leaf phenological patterns have been suggested to play an important role in the variations of productivity, yet, the drivers of leaf shedding and flushing remains unclear. While top-canopy trees likely experience similar aboveground climatic conditions at a given site, their access to water and nutrients may differ due to small-scale variations in edaphic properties. However, conventional methods for characterizing soil physical properties are often labor-intensive, destructive, and provide limited spatial coverage, and this prevents from exploring the role of soil spatial heterogeneity in driving the observed variability in tree functioning.
The SOHO project is an inter-disciplinary project, at the intersection of forest ecology, geophysics, and soil sciences, and aims at characterizing the fine-scale spatial soil heterogeneity to understand observed variability in co-occurring tree phenology. The objectives are 1) to provide a first test case to implement geophysical approaches in a tropical forest in French Guiana to describe variability in soil properties, and 2) to complement the pioneering aboveground monitoring of canopy dynamics provided by the CEBA-funded PhenObs project at individual crown level with a belowground continuous information. More specifically, the project consists in implementing three complementary approaches in four 0.5-ha plots distributed along a topographic gradient across the Guyaflux tower footprint and comparing them to assess spatio-temporal variations in soil properties at fine scales. These methods are i) soil coring and texture analysis; ii) soil water content monitoring using automatic probes; iii) two geophysical approaches, electromagnetic induction (EMI) and electrical resistivity tomography (ERT) to spatially extrapolate the punctual information provided by (i) and (ii). The role of soil variations in driving the observed variability in the timing of leaf shedding and flushing across individuals within the PhenObs dataset will then be tested. In doing so, it will provide an unprecedented opportunity to unravel the diversity of trees functioning within a tropical forest through an integrative way.
THOM-AMAZON – Evolutionary history of thomasomyine rodents: A phylogenomic approach to biogeographical diversification in the Andes and Amazon basin.
PIs: Pierre-Henri Fabre (ISEM, Montpellier, France)
Abstract : Rodent species of the Thomasomyini tribe (Aepeomys, Chilomys, Rhagomys, Rhipidomys, and Thomasomys) are widely distributed in the neotropical rainforests. Despite being a very diverse group of Sigmodontinae, their systematics and biogeography have remained poorly studied. Most Thomasomyini species occur in the Andean mountain forests, ranging from Venezuela to Bolivia, and the Northern Amazonian basin has been proposed as a diversification center for the Andean lineages. However, only a few DNA markers, mostly mitochondrial, have been sequenced for the two highly speciose genera Thomasomys (53 species) found in montane forests and Rhipidomys (28 species), mainly found in the lowland forests from Amazonia. Preliminary analyses based on the cytochrome b gene including Chilomys, Rhipidomys, and Thomasomys found that these two last genera contain many species complexes in need of further taxonomic investigation. Moreover, cytochrome c oxidase I barcodes reveal that R. wetzeli and R. leucodactylus from French Guiana are likely species complexes hiding candidate undescribed species. Our international team has recently developed a nuclear DNA exon capture approach for the genera Aepeomys, Chilomys, and Thomasomys, but we aim to expand this dataset to the closely related Rhipidomys. Our team has access to fresh and historical tissues from most of the Rhipidomys species, including holotypes. In this project, we propose to infer the processes involved in the biogeography and diversification of the Thomasomyini rodents with a special focus on Rhipidomys from the Guiana Shield and the Amazon basin, using an integrative taxonomic approach coupled with next-generation sequencing and phylogenomics.
© Víctor Pacheco
VIRUS-X – Virus diversity in wildlife of French Guiana: A focus on xenarthrans and ticks.
PIs : Olivier Duron (MIVEGEC, Montpellier, France)
Abstract : Viruses are the most abundant and diverse biological entities on Earth. Yet, our current understanding of viral diversity represents only a fraction of their true abundance, with a strong bias toward viruses that directly impact humans and domesticated organisms. The VIRUS-X project aims to break these biases by expanding our knowledge of the virosphere in French Guiana. Using a virion-associated nucleic acid (VANA)-based metagenomics approach, we will analyze 100 xenarthran blood samples and 100 tick samples to uncover the hidden virome of these key organisms.
Ticks and xenarthrans (sloths, armadillos, and anteaters) are of particular interest. Ticks rank among the most important vectors of pathogens affecting both humans and animals, yet the diversity of tick-borne viruses remains largely unexplored. Importantly, we have already identified more than 25 tick species in French Guiana, including species that commonly bite humans, wildlife (including xenarthrans), or both. Xenarthrans, in turn, are reservoirs for a variety of emerging pathogens. Our recent work revealed previously unknown tick-borne pathogens in sloths and armadillos, including closest relatives of a novel intraerythrocytic bacterium we identified as the causative agent of a new human tick-borne disease endemic to French Guiana.
In this context, we hypothesize that ticks and xenarthrans also harbor a rich but entirely unexplored viral diversity. In the VIRUS-X project, our integrated approach, combining field sampling, metagenomics, and phylogenomics, will reveal the composition and structure of these unexplored viral populations. The VIRUS-X project will foster a deeper understanding of the interconnectedness of wildlife health and the prevention of future zoonotic threats, thus contributing to the sustainability of human communities in French Guiana.
© MIVEGEC
