Résumé

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 Lonomia obliqua. However, species identifications have remained largely unchallenged despite improved knowledge of venom diversity and growing evidence that the taxonomy used over past decades misrepresents and underestimates species diversity. Here, we revisit the taxonomic diversity and distribution of Lonomia species using the most extensive dataset assembled to date, combining DNA barcodes, morphological comparisons, and geographical information. Considering new evidence for seven undescribed species as well as three newly proposed nomenclatural changes, our integrative approach leads to the recognition of 60 species, of which seven are known or strongly suspected to cause severe envenomation in humans. From a newly compiled synthesis of epidemiological data, we also examine the consequences of our results for understanding Lonomia envenomation risks and call for further investigations of other species’ venom activities. This is required and necessary to improve alertness in areas at risk, and to define adequate treatment strategies for envenomed patients, including performing species identification and assessing the efficacy of anti-Lonomia serums against a broader diversity of species.

Auteurs, date et publication :

Auteurs Camila González , Liliana Ballesteros-Mejia , Juana Díaz-Díaz , Diana M. Toro-Vargas , Angela R. Amarillo-Suarez , Delphine Gey , Cielo León , Eduardo Tovar , Mónica Arias , Nazario Rivera , Luz Stella Buitrago , Roberto H. Pinto-Moraes , Ida S. Sano Martins , Thibaud Decaëns , Mailyn A. González , Ian J. Kitching , Rodolphe Rougerie , Wuelton M. Monteiro

Publication : PLOS Neglected Tropical Diseases

Date : 2023

Volume : 17

Issue : 2

Pages : e0011063

Catégorie(s)

#CNRS #FORET Nouragues

Auteurs, date et publication :

Auteurs Marcus Schiedung , Philippa Ascough , Severin-Luca Bellè , Robert G. Hilton , Carmen Hoeschen , Steffen A. Schweizer , Samuel Abiven

Date : 2023

Catégorie(s)

#CNRS #Ecotron IleDeFrance #ENS

Résumé

Abstract
Crickets are frequently used as a model in several areas of science, including acoustic communication, behaviour and neurobiology. However, only a few of these studies are placed in an evolutionary framework due to the limited number of phylogenetic hypotheses for true crickets. We present a phylogenetic hypothesis for a newly defined family of crickets, Oecanthidae defin. nov., sister-group of Gryllidae defin. nov. The phylogenetic analyses are based on molecular and morphological data under likelihood and parsimony criteria and molecular data for divergence-times estimation (Bayesian inference). We used 107 terminals from all biogeographic regions and six fossils for the time calibration of the tree. All analyses resulted in Oecanthidae with four subfamilies: Euscyrtinae, Oecanthinae defin. nov., Podoscirtinae defin. nov. and Tafaliscinae defin. nov. Based on our results, we revise the definition and internal classifications of the subfamilies, supertribes and tribes. A new tribe, Phyllogryllini trib. nov. is described. We also update their diagnoses, list the genera of the tribes and list their apomorphies. We provide an identification key for all suprageneric taxa of Oecanthidae, plus all genera of Tafaliscinae. Finally, we discuss the phylogenetic relationships of Oecanthidae, their divergence times, habitat diversity and the importance of ovipositor variation in this clade.

Auteurs, date et publication :

Auteurs Lucas Denadai De Campos , Pedro Guilherme Barrios De Souza Dias , Jorge Alves Audino , Laure Desutter-Grandcolas , Silvio Shigueo Nihei

Publication : Zoological Journal of the Linnean Society

Date : 2023

Volume : 197

Issue : 4

Pages : 1034-1077

Catégorie(s)

#CNRS #FORET Nouragues

Résumé

The isotopic composition of dioxygen in the atmosphere is a global tracer which depends on the biosphere flux of dioxygen toward and from the atmosphere (photosynthesis and respiration) as well as exchanges with the stratosphere. When measured in fossil air trapped in ice cores, the relative concentration of 16O, 17O, and 18O of O2 can be used for several applications such as ice core dating and past global productivity reconstruction. However, there are still uncertainties about the accuracy of these tracers as they depend on the integrated isotopic discrimination of different biological processes of dioxygen production and uptake, for which we currently have very few independent estimates. Here we determined the respiration and photosynthesis fractionation factors for atmospheric dioxygen from experiments carried out in a replicated vegetation–soil–atmosphere analogue of the terrestrial biosphere in closed chambers with growing Festuca arundinacea. The values for 18O discrimination during soil respiration and dark respiration in leaves are equal to -12.3±1.7 ‰ and -19.1±2.4 ‰, respectively. In these closed biological chambers, we also found a value attributed to terrestrial photosynthetic isotopic discrimination equal to +3.7±1.3 ‰. This last estimate suggests that the contribution of terrestrial productivity in the Dole effect may have been underestimated in previous studies.

Auteurs, date et publication :

Auteurs Clémence Paul , Clément Piel , Joana Sauze , Nicolas Pasquier , Frédéric Prié , Sébastien Devidal , Roxanne Jacob , Arnaud Dapoigny , Olivier Jossoud , Alexandru Milcu , Amaëlle Landais

Publication : Biogeosciences

Date : 2023

Volume : 20

Issue : 5

Pages : 1047-1062

Catégorie(s)

#ANR-Citation #CNRS #Ecotron de Montpellier

Résumé

Abstract

Turbidity challenges the visual performance of aquatic animals. During development, environments with limited visibility may affect the fine-tuning of visual systems and thus the perception of, and response to, risk. While turbidity has frequently been used to characterise permanent aquatic habitats, it has been an overlooked feature of ephemeral ones.

Here, we use the natural diversity of ephemeral rearing sites (phytotelmata) in which the tadpoles of two poison frog species are deposited and confined until metamorphosis to explore the relationship between environments with limited visibility and response to perceived risk.

We sampled wild tadpoles of
Dendrobates tinctorius
, a rearing-site generalist with facultatively cannibalistic tadpoles, and
Oophaga
(formerly
Dendrobates
)
pumilio
, a small-phytotelm specialist dependent on maternal food-provisioning, to investigate how the visual environment in rearing sites influences tadpole behaviour. We hypothesised that turbid rearing conditions negatively impact both species’ ability to perceive risk, decreasing response strength to predatory visual stimuli. Using experimental arenas, we measured tadpole activity and space first on a black and white background, and then on either black or white backgrounds where tadpoles were exposed to visual stimuli of (potentially cannibalistic) conspecifics or potential predators.

When placed in a novel arena, the effects of rearing environment on
D. tinctorius
tadpoles were clear: tadpoles from darker pools were less active than tadpoles from brighter pools, and did not respond to either visual stimuli, whereas tadpoles from brighter pools swam more when paired with conspecifics versus odonate larvae, suggesting that tadpoles can visually discriminate between predators. For
O. pumilio
, tadpoles were more active on experimental backgrounds that more closely matched the luminosity of their rearing sites, but their responses to the two visual stimuli did not differ.

Larval specialisation associated with species-specific microhabitat use may underlie the observed responses to visual stimuli, which has implications for the stability of species interactions and trophic dynamics in pool communities. Together, our findings demonstrate that light availability of wild larval rearing conditions influences the perception of risk in novel contexts, and provide insight into how visually guided animals may respond to sudden environmental disturbances.

Auteurs, date et publication :

Auteurs Chloe A. Fouilloux , Jennifer L. Stynoski , Carola A. M. Yovanovich , Bibiana Rojas

Date : 2023

Catégorie(s)

#CNRS #FORET Nouragues

Résumé

The predicted increases in drought in many forest ecosystems may alter soil microbial community diversity and activity, which may further depend on tree species richness. Shifts in microbial community composition and activity could engender changes in ecosystem function, notably, in soil greenhouse gas emissions and C storage. Using soils from mono-specific and mixed three-species forest stands from across Europe, we performed a microcosm experiment to test how soil microbial taxonomic and catabolic diversity are affected by repeated drying-rewetting (DRW) cycles and tree species mixing. We used Illumina sequencing and MicroResp™ analyses to explore community-level changes between microbial functional groups. DRW decreased bacterial richness and carbon substrate use diversity and increased fungal Shannon diversity. Additionally, microbial communities exposed to DRW changed their consumption of 11 out of 15 substrates significantly, suggesting microbial functional shifts. The legacy effect of tree species mixing influenced the structure of the microbial communities (i.e. taxonomic differential abundance) although, community weighted mean (CWM) values of absorptive root traits appeared to affect more strongly microbial richness, relative abundance, and Shannon diversity. No significant tree species mixing:DRW interaction was found for most microbial variables, except for the use of certain substrates and potentially differential abundance. Our data from a laboratory experiment with soils from different forest ecosystems underline that drought may cause shifts in microbial taxonomic and catabolic diversity, while tree species influences primarily taxonomic diversity through root traits.

Auteurs, date et publication :

Auteurs Lauren M. Gillespie , Luis Daniel Prada-Salcedo , Ammar Shihan , Nathalie Fromin , Kezia Goldmann , Alexandru Milcu , François Buscot , Bruno Buatois , Stephan Hättenschwiler

Publication : Pedobiologia

Date : 2023

Volume : 97-98

Pages : 150875

Catégorie(s)

#ANR-Citation #CNRS #Ecotron de Montpellier

Résumé

Causal effects of biodiversity on ecosystem functions can be estimated using experimental or observational designs — designs that pose a tradeoff between drawing credible causal inferences from correlations and drawing generalizable inferences. Here, we develop a design that reduces this tradeoff and revisits the question of how plant species diversity affects productivity. Our design leverages longitudinal data from 43 grasslands in 11 countries and approaches borrowed from fields outside of ecology to draw causal inferences from observational data. Contrary to many prior studies, we estimate that increases in plot-level species richness caused productivity to decline: a 10% increase in richness decreased productivity by 2.4%, 95% CI [−4.1, −0.74]. This contradiction stems from two sources. First, prior observational studies incompletely control for confounding factors. Second, most experiments plant fewer rare and non-native species than exist in nature. Although increases in native, dominant species increased productivity, increases in rare and non-native species decreased productivity, making the average effect negative in our study. By reducing the tradeoff between experimental and observational designs, our study demonstrates how observational studies can complement prior ecological experiments and inform future ones.

Auteurs, date et publication :

Auteurs Laura E. Dee , Paul J. Ferraro , Christopher N. Severen , Kaitlin A. Kimmel , Elizabeth T. Borer , Jarrett E. K. Byrnes , Adam Thomas Clark , Yann Hautier , Andrew Hector , Xavier Raynaud , Peter B. Reich , Alexandra J. Wright , Carlos A. Arnillas , Kendi F. Davies , Andrew MacDougall , Akira S. Mori , Melinda D. Smith , Peter B. Adler , Jonathan D. Bakker , Kate A. Brauman

Publication : Nature Communications

Date : 2023

Volume : 14

Issue : 1

Pages : 2607

Catégorie(s)

#ANR-Citation #CEREEP #CNRS #ENS

Résumé

A new species of Hypaeus Simon 1900 is described from French Guiana based on both sexes, Hypaeus olympeae sp. nov. We employed morphological evidence, field observation, as well as the mitochondrial COI rapidly evolving loci to confirm that both males and females belong to the same species. Finally, nine species are newly recorded for the salticid fauna of French Guiana, Cyllodania fasciata (Caporicaco, 1954) syn. nov. is considered junior synonym of Gypogyna forceps Simon, 1900 and 12 COI sequences corresponding to four previously unsequenced Hypaeus species are added to GenBank.

Auteurs, date et publication :

Auteurs Cyril Courtial , Kaïna Privet , Xavier Aubriot , Lionel Picard , Julien Pétillon

Publication : Studies on Neotropical Fauna and Environment

Date : 2023

Volume : 58

Issue : 2

Pages : 439-447

Catégorie(s)

#CNRS #FORET Nouragues

Résumé

The neotropical Apicotermitinae is a common and widespread clade of mostly soil-feeding soldierless termites. With few exceptions, species of this group were originally assigned to the genus Anoplotermes Müller, 1873. The application of internal worker morphology coupled with genetic sequencing has recently shed light on the true diversity of this subfamily. Herein, Anoplotermes susanae Scheffrahn, Carrijo & Castro, sp. nov. and four new species in four new genera are described: Hirsutitermes kanzakii Scheffrahn, Carrijo & Castro, gen. nov. et sp. nov., Krecekitermes daironi Scheffrahn, Carrijo & Castro, gen. nov. et sp. nov., Mangolditermes curveileum Scheffrahn, Carrijo & Castro, gen. nov. et sp. nov., and Ourissotermes giblinorum Scheffrahn, Carrijo & Castro, gen. nov. et sp. nov. Worker descriptions are based mainly on worker gut morphology, including the enteric valve, while imagoes were described based on external characters. A Bayesian phylogenetic tree of New World Apicotermitinae was constructed using the complete mitogenome to infer genera relationships and corroborate the taxonomic decisions. Distribution maps and a dichotomic key to the known Neotropical Apicotermitinae genera are provided.

Auteurs, date et publication :

Auteurs Tiago F. Carrijo , Daniel Castro , Menglin Wang , Joice P. Constantini , Thomas Bourguignon , Eliana M. Cancello , Yves Roisin , Rudolf H. Scheffrahn

Publication : ZooKeys

Date : 2023

Volume : 1167

Pages : 317-352

Catégorie(s)

#CNRS #FORET Nouragues

Résumé

Triple oxygen isotopes (17O-excess) of water are useful to trace evaporation at the soil–plant–atmosphere interface. The 17O-excess of plant silica, i.e., phytoliths, inherited from leaf water, was previously calibrated in growth chambers as a proxy of atmospheric relative humidity (RH). Here, using a model–data approach, we examine the parameters that control the triple oxygen isotope composition of bulk grass leaf water and phytoliths in natura, at the O3HP experimental platform located in the French Mediterranean area. A grass plot was equipped to measure for 1 year, all environmental and plant physiological parameters relevant for modeling the isotope composition of the grass leaf water. In particular, the triple oxygen and hydrogen isotope composition of atmospheric water vapor above the grass was measured continuously using a cavity ring-down spectrometer, and the grass leaf temperature was monitored at plot scale using an infrared (IR) radiometer. Grass leaves were collected in different seasons of the year and over a 24 h period in June. Grass leaf water was extracted by cryogenic vacuum distillation and analyzed by isotope ratio mass spectrometry (IRMS). Phytoliths were analyzed by IR–laser fluorination–IRMS after chemical extraction. We showed that the traditional Craig–Gordon steady-state model modified for grass leaves reliably predicts the triple oxygen isotope composition of leaf water during daytime but is sensitive to uncertainties on the leaf-to-air temperature difference. Deviations from isotope steady state at night are well represented in the triple oxygen isotope system and predictable by a non-steady-state model. The 17O-excess of phytoliths confirms the applicability of the 17O-excessphyto vs. RH equation established in previous growth chamber experiments. Further, it recorded average daytime RH over the growth period rather than daily RH, related to low transpiration and silicification during the night. This model–data approach highlights the utility of the triple oxygen isotope system to improve the understanding of water exchange at the soil–plant–atmosphere interface. The in natura experiment underlines the applicability of 17O-excess of phytoliths as a RH proxy.

Auteurs, date et publication :

Auteurs Claudia Voigt , Anne Alexandre , Ilja M. Reiter , Jean-Philippe Orts , Christine Vallet-Coulomb , Clément Piel , Jean-Charles Mazur , Julie C. Aleman , Corinne Sonzogni , Helene Miche , Jérôme Ogée

Publication : Biogeosciences

Date : 2023

Volume : 20

Issue : 11

Pages : 2161-2187

Catégorie(s)

#ANR-Citation #CNRS #Ecotron de Montpellier #FORET O3HP