Thibaud Decaëns

Université de Montpellier | UM1 · Centre d’Écologie Fonctionnelle et Évolutive (CEFE)

Biological invasions are increasingly rec-ognized as a potent force altering native ecosystems worldwide. Many of the best documented cases involve the massive invasions of North America by plant and animal taxa native to Europe. In this study, we use DNA barcoding to survey the occurrence and genetic structure of two major groups of soil inverte-b...

Aim To review published evidence regarding the factors that influence the geographic variation in diversity of soil organisms at different spatial scales. Location Global. Methods A search of the relevant literature was conducted using the Web of Science and the author's personal scientific database as the major sources. Special attention was paid...

Understanding the relative importance of biotic interactions, multiple environmental drivers, and neutral processes in shaping community diversity and composition is a central question for both theoretical and applied ecology. We analysed a dataset describing 125 earthworm communities sampled in 10 localities in French Guiana. DNA barcodes were use...

Tropical rainforests are among the most emblematic ecosystems in terms of biodiversity. However, our understanding of the structure of tropical biodiversity is still incomplete, particularly for certain groups of soil organisms such as earthworms, whose importance for ecosystem functioning is widely recognised. This study aims at determining the re...

Estimating the overall number of species for a given taxon is a central issue in ecology and conservation biology. It should be particularly topical in the case of soil organisms, which represent the majority of known species, but it still suffers from a considerable taxonomic knowledge deficit. We propose here an estimation of the global number of...

Earthworms are key organisms of soil ecosystems, however, the determinants of the structure and distribution of earthworm communities and their relationships with agricultural practices are not well-studied in Canada. We sampled earthworm communities from four different habitat types along a disturbance gradient: agricultural crop land, forest arou...

Earthworms represent a crucial taxon in soil ecosystems in terms of biomass and ecological functions. Knowledge of their diversity is growing, but the understanding of the ecological and evolutionary mechanisms underlying this diversity and its distribution patterns remains poorly understood. This is partly due to a lack of community data available...

Global biodiversity gradients are generally expected to reflect greater species replacement closer to the equator. However, empirical validation of global biodiversity gradients largely relies on vertebrates, plants, and other less diverse taxa. Here we assess the temporal and spatial dynamics of global arthropod biodiversity dynamics using a beta-...

Highlights • The earthworm population in Montpellier exhibits remarkably high genetic diversity. • Haplotypic and nucleotidic diversities of earthworms are influenced by environmental factors. • Cryptic lineages were identified in three earthworm species. • Human-mediated transports significantly contribute to the distribution patterns of earthw...

Recent research on earthworms has shed light on their global distribution, with high alpha richness in temperate zones and high beta diversity in tropical areas. Climate and agricultural practices, notably plowing and conservation methods, were shown to strongly influence earthworm communities. However, data gaps persist in regions like North Austr...

Corsica and Sardinia are amongst the largest islands of the Western Mediterranean. Their complex geological history included belonging to the European–Iberian continental margin (close to current-day Catalonia and Provence) and varying degrees of isolation for the last 30 million years, leading to peculiar, highly endemic faunas and floras. This is...

Background Soil animal communities include more than 40 higher-order taxa, representing over 23% of all described species. These animals have a wide range of feeding sources and contribute to several important soil functions and ecosystem services. Although many studies have assessed macroinvertebrate communities in Brazil, few of them have been pu...

Southern France has been highlighted as an important hotspot of earthworm diversity mostly by the work of Marcel Bouché, who sampled more than 1300 localities in mainland France including Corsica in the 1960s. We resampled some of the Bouché's localities and conducted molecular phylogenetic analyses. It leads to the identification of a new Lumbrici...

The three main ecological categories of earthworms (anecic, endogeic, epigeic) are often used as proxies for functional groups. This is troublesome since they were not designed for this purpose and thus the relevance of such a use was never tested nor proven. How earthworms influence the different soil functions is tightly linked to their bioturbat...

The genus Aporrectodea includes some of the most conspicuous earthworm species, but its taxonomic history is among the most complex within the family Lumbricidae. Molecular phylogenetic studies have produced some advances by assigning former Aporrectodea species to other monophyletic clades and by detecting species level lineages within the cosmopo...

Despite the importance of earthworms for soil formation, more is needed to know about how Pre-Columbian modifications to soils and the landscape. Gaining a deeper understanding is essential for comprehending the historical drivers of earthworm communities and the development of effective conservation strategies in the Amazon rainforest. Human distu...

Impacts of tree diversity on forest soil fauna remain poorly known. Two groups of functionally similar invertebrates, millipedes (Diplopoda) and woodlice (Isopoda, Oniscidea), were sampled at 61 forest plots in four European countries (Finland, Poland, Romania, Italy) in order to (1) compare the abundance and species richness of these saprophagous...

Since the 18th century, several taxonomists have contributed to knowledge of the French earthworm fauna, one of the best-known earthworm communities in Europe, with 164 species currently described. Surprisingly, new species keep being added constantly, even large ones, which are usually the first to be described. The recent discovery of six undescr...

Abstract Elevational gradients are characterized by major shifts in environmental conditions, reflected through changes in climatic and soil variables. These shifts strongly impact the composition, community structure and specific functional traits of vegetation. Vegetation, in turn, influences soil properties through litter input, root growth and...

We launch an initiative to build a collection of pictures of earthworm species with good identification, both in the field and in the lab. We use iNaturalist to reach non scientists and also to improve iNat's computer vision engine.

In the current paper we present an updated checklist of all the megadrile earthworms (Crassiclitellata: Annelida) in the world, and notes on the distribution of families worldwide. Biogeographic responses to geological phenomena including plate tectonics, as well as to past and present climate and habitat distributions, are the main factors determi...

Hormogastrid earthworms are found in the diversity hotspot of the Franco-Iberian domain, together with the better-known family Lumbricidae. Integrative systematics (the combination of morphological, molecular and ecological data) have increased our knowledge of the diversity and evolutionary history of these earthworms, highlighting unresolved taxo...

Caterpillars of the Neotropical genus Lonomia (Lepidoptera: Saturniidae) are responsible for some fatal envenomation of humans in South America inducing hemostatic disturbances in patients upon skin contact with the caterpillars’ spines. Currently, only two species have been reported to cause hemorrhagic syndromes in humans: Lonomia achelous and Lo...

The taxonomy of earthworms has been riddled by instability, lack of systematically useful characters, and lax diagnoses of some genera. This has led to the use of some genera such as Allolobophora Eisen, 1874 as taxonomic wastebaskets, blurring their evolution and biogeographical history. The implementation of molecular techniques has revolutionize...

Scherotheca Bouché, 1972 is a highly diverse genus of Lumbricidae Rafinesque-Schmaltz, 1815, broadly distributed from Northern Italy and Corsica Island to the Pyrenees and Northeastern Iberian Peninsula. A recent survey of earthworm species diversity in Corsica resulted in the identification of 12 operational taxonomic units (OTU) within Scherothec...

This poster, designed by Pierre Ganault, presetend the sOilFauna project to the SFE²-GfÖ-EEF conference in Metz on November 2022. The poster is largely inspired by the publication by Mathieu et al., 2022 Soil Organisms 10.25674/so94iss2id282

Global gradients in species biodiversity are expected to reflect tighter packing of species closer to the equator. Yet, empirical validation of these patterns has so far focused on less diverse taxa, with comparable assessments of mega-diverse groups historically constrained by the taxonomic impediment. Here we assess the temporal and spatial turno...

Aim: Global gradients in species biodiversity may or may not be associated with greater species replacement closer to the equator. Yet, empirical validation of these patterns has so far focused on less diverse taxa, with comparable assessments of mega-diverse groups historically constrained by the taxonomic impediment. Location: Global Time period:...

The study of elevational diversity gradients is a central topic in biodiversity research. In this study, we tested for the effect of climate, resource quality and habitat heterogeneity on earthworm communities along an altitudinal gradient and around the treeline in the French Alps. Earthworm communities and environmental properties (i.e. climate,...

Although DNA barcodes-based operational taxonomic units (OTUs) are increasingly used in earthworm research, the relative efficiency of the different methods available to delimit them has not yet been tested on a comprehensive dataset. For this study, we used three datasets containing 651, 2304 and 4773 COI barcodes of earthworms from French Guiana,...

Caterpillars of the Neotropical genus Lonomia (Lepidoptera: Saturniidae) are responsible for some fatal envenomation of humans in South America inducing hemostatic disturbances in patients upon skin contact with the caterpillars' spines. Currently, only two species have been reported to cause hemorrhagic syndromes in humans: Lonomia achelous and Lo...

Les catégories écologiques de vers de terre définies par Marcel Bouché sur les vers de terre français entre 1971 et 1977 ont eu un succès mondial et sont maintenant utilisées par tous les auteurs de tous les continents. Cependant, deux glissements de sens et d'usage peuvent être décelés dans la littérature scientifique. Le premier est que la plupar...

Understanding global biodiversity change, its drivers, and the ecosystem consequences requires a better appreciation of both the factors that shape soil macrofauna communities and the ecosystem effects of these organisms. The project "sOilFauna" was funded by the synthesis center sDiv (Germany) to address this major gap by forming a community of so...

Classifying organisms has a wide use and a long history in ecology. However, the meaning of a 'group of or-ganisms' and how to group organisms is still the subject of much theoretical and empirical work. Achieving this long quest requires simplifying the complexity of species niches for which relevant morphological, behavioural, biochemical or life...

The soil fauna of the tropics remains one of the least known components of the biosphere. Long-term monitoring of this fauna is hampered by the lack of taxonomic expertise and funding. These obstacles may potentially be lifted with DNA metabarcoding. To validate this approach, we studied the ants, springtails and termites of 100 paired soil samples...

Aim Macroinvertebrates comprise a highly diverse set of taxa with great potential as indicators of soil quality. Communities were sampled at 3,694 sites distributed world‐wide. We aimed to analyse the patterns of abundance, composition and network characteristics and their relationships to latitude, mean annual temperature and rainfall, land cover,...

A bstract Wild silkmoths (Saturniidae) are one of the most emblematic and most studied families of moths. Yet, the absence of a robust phylogenetic framework based on a comprehensive taxonomic sampling impedes our understanding of their evolutionary history. We analyzed 1,024 ultraconserved elements (UCEs) and their flanking regions to infer the re...

• Global insect decline has recently become a cause for major concern, particularly in the tropics where the vast majority of species occurs. Deforestation is suggested as being a major driver of this decline, but how anthropogenic changes in landscape structure affect tropical insect communities has rarely been addressed. • We sampled Saturniidae...

Saprophagous macroarthropods are important actors in litter decomposition as they process large amounts of litter and transform it into fecal pellets that differ in chemical and physical properties compared to ingested litter. When having a choice among several litter types, saprophagous macroarthropods exhibit feeding preferences depending on thei...

Les catégories écologiques de vers de terre définies par Marcel Bouché sur les vers de terre français entre 1971 et 1977 ont eu un succès mondial et sont maintenant utilisées par tous les auteurs de tous les continents. Cependant, deux glissements de sens et d'usage peuvent être décelés dans la littérature scientifique. Le premier est que la plupar...

Earthworm systematics have been limited by the small number of taxonomically informative morphological characters and high levels of homoplasy in this group. However, molecular phylogenetic techniques have yielded significant improvements in earthworm taxonomy in the last 15 years. Several different approaches based on the use of different molecula...

The Massif Central in France could potentially harbor numerous ancient endemic lineages owing to its long history of continuous geological stability. Several endemic earthworm species inhabit the area, with Allolobophora (Gatesona) chaetophora, Helodrilus (Acystodrilus) and Avelona ligra showing hints of a common evolutionary origin. However, the p...

The historical biogeography of the Lumbricidae, the main Palearctic earthworm family, may be linked to the paleogeography of their putative ancestral range in Iberia–southeastern France–Corsica–Sardinia. Although molecular phylogenetics has recently been used to analyze most endemic genera in this area, the genus Kritodrilus has not yet been studie...

Soil organic matter (OM) is a complex heterogeneous mixture: resulting from decomposition and organo-mineral interactions, it challenges characterization in terms of composition and biogeochemical stability. From this perspective, the Rock-Eval® method is a rapid and efficient thermal analysis, which combines quantitative and qualitative informatio...

Soil fauna communities are major drivers of many forest ecosystem processes. Tree species diversity and composition shape soil fauna communities, but their relationships are poorly understood, notably whether or not soil fauna diversity depends on tree species diversity. Here, we characterized soil macrofauna communities from forests composed of ei...

Amazonian rainforests, once thought to be pristine wilderness, are increasingly known to have been widely inhabited, modified, and managed prior to European arrival, by human populations with diverse cultural backgrounds. Amazonian Dark Earths (ADEs) are fertile soils found throughout the Amazon Basin, created by pre‐Columbian societies with sedent...

The Saturniidae is one of the most emblematic families of moths, comprising nearly 3000 species distributed globally. In this study, DNA barcode analysis and comparative morphology were combined to describe three new species within the genus Automeris, which is the most diverse genus in the family. Automeris llaneros Decaëns, Rougerie & Bonilla, sp...

Despite their recognized essential role in soil, earthworms in tropical environments are still understudied. The aim of this study was to re-evaluate the diversity at the regional scale, as well as to investigate the environmental and spatial drivers of earthworm communities. We sampled earthworm communities across a range of habitats at six locali...

James et al . claim that there are areas of concern in our work. We believe that they have misunderstood the methods behind our paper and that differences in scale have been overlooked. Once those misunderstandings have been resolved, their remaining criticisms are either not sustained or agree with our statements. To advance the field, we recommen...

Objectives Altitude integrates changes in environmental conditions that determine shifts in vegetation, including temperature, precipitation, solar radiation and edaphogenetic processes. In turn, vegetation alters soil biophysical properties through litter input, root growth, microbial and macrofaunal interactions. The belowground traits of plant c...

Identifying the determinants of the distribution of soil organism communities at different spatial scales is essential to our understanding of the functioning of terrestrial ecosystems. Indeed, spatial patterns of soil biota, and the factors that determine them, influence spatial patterns of many ecological processes such as the decomposition of or...

Soil is one of the most biodiverse terrestrial habitats. Yet, we lack an integrative conceptual framework for understanding the patterns and mechanisms driving soil biodiversity. One of the underlying reasons for our poor understanding of soil biodiversity patterns relates to whether key biodiversity theories (historically developed for aboveground...

We used the COI marker, the most popular DNA barcode for the animal kingdom, to assess the taxonomic status of Corsican populations of eight groups of species of ants that occur both on Corsica and the European mainland. (i) In two groups, we detected no genetic differentiation between Corsica and the continent. Absence of differentiation across va...

Comparative phylogeography is a powerful methodological approach to understand the particular evolutionary phenomena that occur in islands. This method has been rarely applied to insular earthworm communities. These soil animals show a striking dichotomy in their phylogeographic patterns: deeply divergent, regionally structured linages and widely d...

Despite their recognized essential role in soil, earthworms in tropical environments are still understudied. The aim of this study was to re-evaluate the diversity at the regional scale, as well as to investigate the environmental and spatial drivers of earthworm communities. We sampled earthworm communities across a range of habitats at six locati...

The area comprising the Pyrenees, Northeast Spain, Southern France and Corsica-Sardinia supports a large part of the diversity of Lumbricidae earthworms, including most species of the endemic genera Prosellodrilus, Cataladrilus and Scherotheca. In this region, the probability of encountering new species for science is significant, especially in sca...

Pontoscolex corethrurus is a well-known invasive earthworm in tropical zone which is believed to have originated from the Guayana Shield in South America and was described as parthenogenetic. A recent phylogenetic study revealed four cryptic species in the P. corethrurus complex (L1, L2, L3 and L4), among them L1 was particularly widespread and was...

This Handbook of methods aim to provide the different techniques and methodologies to obtain a minimum data set of variables, from soil biodiversity assessment to SOM dynamics, including, isotope analysis, bioturbation assessment and metagenomics. With the knowledge gathered in forthcoming projects and studies, researchers (biogeochemists and soil...

Un premier inventaire de la diversité spécifique des vers de terre a été réalisé dans le Parc national de Port-Cros. Les échantillons collectés dans les secteurs du cap Lardier, Port-Cros et Porquerolles ont été identifiés en combinant diagnoses morphologiques et analyses des codes-barres ADN. Un total de 15 espèces, certaines remarquables, a été o...

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