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International audience; Early effects induced by cysteine were monitored using the model of Mimosa pudica pulvinar cells. Rapid dose-dependent membrane depolarization (within seconds) and modification of proton secretion (within minutes) were triggered at cysteine concentrations higher than 0.1 mM. These effects did not result from a modification of the plasma membrane H+-ATPase activity nor from a protonophore effect as shown by assays on plasma membrane vesicles isolated from pulvinar tissues. In a 0.5–10 mM range, cysteine inhibited the ion-driven turgor-mediated seismonastic reaction of Mimosa pudica primary pulvini and the dark-induced movement of Cassia fasciculata leaflets. At concentrations higher than 1 mM, it induced a long-lasting leaflet necrosis dependent on the concentration and treatment duration. Electron microscopy showed that cysteine induced important damage in the nucleus, mitochondria, endoplasmic reticulum and Golgi of the M. pudica motor cell. Cysteine inhibited in a concentration-dependent manner, from 0.5 to 20 mM, both the mycelial growth and the spore germination of the fungal pathogens Phaeomoniella chlamydospora and Phaeoacremonium minimum implicated in esca disease of grapevines. Using [35S] cysteine, we showed that the amino acid was absorbed following leaf spraying, translocated from leaves to other parts of grapevine cuttings and accumulated within trunks and roots. Therefore, cysteine showed relevant properties to be a candidate able to control fungal diseases either by acting as an early signal directing plant host reaction or/and by acting directly on fungal development.

10 pages; International audience; Carbon dioxide released in the atmosphere and dissolved in water leads to acidification. Relatively few studies have focused on fresh waters, where biocalcifying species are more readily impacted by changes in pH. Sensitivity to pH of an endangered calcium-demanding organism, the crayfish Austropotamobius pallipes, was investigated in the Pinail nature reserve, a natural system with 3000 permanent ponds, some inhabited by the crayfish and others not, originally due to human introduction. From the 14 chemical parameters measured in this study, the main limiting factor preventing crayfish establishment appears to be water acidity (pH < 6.8), which affects calcification, molting, growth and reproduction. We predict that 20% of the Pinail populations will disappear by 2060 due to freshwater acidification with the present level of fossil fuel consumption. Ongoing and future restoration projects for conservation of this heritage crustacean must select hard water with the highest water pH (> 7).

International audience; Aphids constitute a major group of crop pests that inflict serious damages to plants, both directly by ingesting phloem and indirectly as vectors of numerous diseases. In response to intense and repeated human-induced pressures, such as insecticide treatments, the use of resistant plants and biological agents, aphids have developed a series of evolutionary responses relying on adaptation and phenotypic plasticity. In this review, we highlight some remarkable evolutionary responses to anthropogenic pressures in agroecosystems and discuss the mechanisms underlying the ecological and evolutionary success of aphids. We outline the peculiar mode of reproduction, the polyphenism for biologically important traits and the diverse and flexible associations with microbial symbionts as key determinants of adaptive potential and pest status of aphids.

International audience; Occurrence of functional interactions between Sr2+ and Ca2+ were investigated on maize plants grown under hydroponic conditions in presence of various mixtures of SrCl2 [0-0.01-1-10 mM] and CaCl2 [0-0.2-2-20 mM]. External [Ca2+] modulated the effect of Sr2+ on the plant dry weight, and on the Sr2+, Ca2+ and Mg2+ contents of roots and shoots. An intermediary functional step between external [Sr2+] and [Ca2+], and organ ion content, occurred at the plasma membrane of cortical root cells where Sr2+ and Ca2+ could influence ion uptake by acting on membrane potential. The decrease of the Sr2+-evoked membrane depolarization induced by Ca2+ could not solely be attributed to the Ca2+-effect on the resting membrane potential. Most of the time the individual effects of Sr2+ and Ca2+ were not additive, as these two ions clearly interacted with each other to jointly affect the plant physiology. In spite of these interactions, both [Sr2+]ext or [Sr2+]ext/[Ca2+]ext ratio values seemed to enable a correct prediction of the Sr2+-effects on the plant. However using the [Sr2+]ext/[Ca2+]ext ratio improved significantly the adequacy of prediction compared to the use of [Sr2+]ext alone, as it increased up to 25% the proportion of variability accounted for by the model.

7 pages; International audience; Maternally inherited Wolbachia (α-Proteobacteria) are widespread parasitic reproductive manipulators. A growing number of studies have described the presence of different Wolbachia strains within a same host. To date, no naturally occurring multiple infections have been recorded in terrestrial isopods. This is true for Armadillidium vulgare which is known to harbor non simultaneously three Wolbachia strains. Traditionally, such Wolbachia are detected by PCR amplification of the wsp gene and strains are characterized by sequencing. The presence of nucleotide deletions or insertions within the wsp gene, among these three different strains, provides the opportunity to test a novel genotyping method. Herein, we designed a new primer pair able to amplify products whose lengths are specific to each Wolbachia strain so as to detect the presence of multi-infections in A. vulgare. Experimental injections of Wolbachia strains in Wolbachia-free females were used to validate the methodology. We re-investigated, using this novel method, the infection status of 40 females sampled in 2003 and previously described as mono-infected based on the classical sequencing method. Among these females, 29 were identified as bi-infected. It is the first time that naturally occuring multiple infections of Wolbachia are detected within an individual A. vulgare host. Additionally, we resampled 6 of these populations in 2010 to check the infection status of females.

International audience

International audience; Climate and land use/land cover (LULC) change are two major global change factors driving shifts in the location of suitable areas for many species. Here, we assessed if a low-vagility newt, Triturus marmoratus, can track displacement of suitable areas by 2100, and tested whether climate or LULC changes are primary drivers of the species’ future distribution. We combined niche modelling with the process-based model simRShift to improve biological relevance and simulate species dispersal by 2100 under scenarios of climate and LULC changes at high spatial resolution. Our results show that T. marmoratus could lose a significant part of its current French range in the coming decades, and that the range loss will primarily be driven by climate change, with LULC change playing a secondary role. The species seems unlikely to be able to track the northern shift of its suitable habitat as rapidly as required given the rate of climate warming during the 21st century. This is due to insufficient dispersal ability, which is compounded by the magnitude of habitat fragmentation in the human-dominated landscape. We highlight the need to assess vulnerability and anticipate threats arising from global change even for species that are not currently considered endangered. We identified areas where the species is most likely to occur and be extinct in the future, which can serve as a guide for population monitoring. Our framework can support conservation strategy development by defining ecological corridors that would assist species to track their required habitats in the face of global change.

In a greenhouse experiment, we investigated the influence of leek (Allium porrum) intercropping, mycorrhizal fungi and earthworms on the root-knot nematode infection by Meloidogyne incognita (RKN) and the growth and development of tomato plants (Solanum lycopersicum). Tomato plants were grown in pots, intercropped with leeks or in monoculture, and earthworms and/or arbuscular mycorrhizal fungi (AMF) were introduced. The effects of these two treatments on root-knot nematode infection and tomato plant growth and development were assessed i) by counting the galls induced by the nematodes and the number of egg masses on their roots, and ii) by measuring their height increase, shoot and root dry biomasses and flowering time. Tomato growth was increased with leek compared to the monoculture (e.g., +82% shoot biomass), probably due to a lower plant-plant competition, although a facilitation effect cannot be excluded. The presence of leeks did not reduce the number of galls (per g of root). The presence of AMF (Rhizophagus irregularis) increased the overall infection of M. incognita (e.g., +36% egg masses) and induced more galls with multiple egg masses in the leek-tomato association (+71%) but did not increase plant biomass. On the other hand, it increased plant height in presence of the compost earthworms (Eisenia andrei) compared to earthworms alone with RKN (+2%). It also delayed the flowering compared to RKN alone (+7.6 days in average). Competition between the two tomato plants in monoculture probably strongly impacted plant growth, flowering time and thereby the RKN infection, but leek-tomato interactions should be further examined. The overall increased number of multiple egg masses per gall in presence of AMF is contrary to its protective effect reported in the litterature.

Bdelloid rotifers are notorious as a speciose ancient clade comprising only asexual lineages. Thanks to their ability to repair highly fragmented DNA, most bdelloid species also withstand complete desiccation and ionizing radiation. Producing a well-assembled reference genome is a critical step to developing an understanding of the effects of long-term asexuality and DNA breakage on genome evolution. To this end, we present the first high-quality chromosome-level genome assemblies for the bdelloid Adineta vaga, composed of six pairs of homologous (diploid) chromosomes with a footprint of paleotetraploidy. The observed large-scale losses of heterozygosity are signatures of recombination between homologous chromosomes, either during mitotic DNA double-strand break repair or when resolving programmed DNA breaks during a modified meiosis. Dynamic subtelomeric regions harbor more structural diversity (e.g. chromosome rearrangements, transposable elements, and haplotypic divergence). Our results trigger the reappraisal of potential meiotic processes in bdelloid rotifers and help unravel the factors underlying their long-term asexual evolutionary success., SCOPUS: ar.j, info:eu-repo/semantics/published

1. Urban ecosystems can sustain populations of wild bees, partly because of their rich native and exotic floral resources. A better understanding of the urban bee diet, particularly at the larval stage, is necessary to understand biotic interactions and feeding behaviour in urban ecosystems, and to promote bees by improving the management of urban floral resources. 2. We investigated the larval diet and distribution patterns of four solitary wild bee species with different diet specialization (i.e. Chelostoma florisomne, Osmia bicornis, Osmia cornuta and Hylaeus communis) along urban intensity gradients in five European cities (Antwerp, Paris, Poznan, Tartu and Zurich) using two complementary analyses. Specifically, using trap-nests and pollen metabarcoding techniques, we characterized the species' larval diet, assessed diet consistency across cities and modelled the distribution of wild bees using species distribution models (SDMs). 3. Our results demonstrate that urban wild bees display different successful strategies to exploit existing urban floral resources: not only broad generalism (i.e. H. communis) but also intermediate generalism, with some degree of diet conservatism at the plant family or genus level (i.e. O. cornuta and O. bicornis), or even strict specialization on widely available urban pollen hosts (i.e. C. florisomne). Furthermore, we detected important diet variation in H. communis, with a switch from an herbaceous pollen diet to a tree pollen diet with increasing urban intensity. 4. Species distribution modelling indicated that wild bee distribution ranges inside urban ecosystems ultimately depend on their degree of specialization, and that broader diets result in less sensitivity to urban intensity. 5. Policy implications. Satisfying larval dietary requirements is critical to preserving and enhancing wild bee distributions within urban gradients. For high to intermediate levels of feeding specialization, we found considerable consistency in the preferred plant families or genera across the studied cities, which could be generalized to other cities where these bees occur. Identifying larval floral preferences (e.g. using pollen metabarcoding) could be helpful for identifying key plant taxa and traits for bee survival and for improving strategies to develop bee-friendly cities., Journal of Applied Ecology, 59 (2), ISSN:0021-8901, ISSN:1365-2664

Sex chromosomes are generally derived from a pair of autosomes that have acquired a locus controlling sex. Sex chromosomes may evolve reduced recombination around this locus and undergo a long process of molecular divergence. At that point, the original loci controlling sex may be difficult to pinpoint. This difficulty has affected many model species from mammals to birds to flies, which present highly diverged sex chromosomes. Identifying sex-controlling loci is easier in species with molecularly similar sex chromosomes. Here we aimed at pinpointing the sex-determining region (SDR) of Armadillidium vulgare, a terrestrial isopod with female heterogamety (ZW females and ZZ males) and whose sex chromosomes appear to show low genetic divergence. To locate the SDR, we assessed single-nucleotide polymorphism (SNP) allele frequencies in F1 daughters and sons sequenced in pools (pool-seq) in several families. We developed a Bayesian method that uses the SNP genotypes of individually sequenced parents and pool-seq data from F1 siblings to estimate the genetic distance between a given genomic region (contig) and the SDR. This allowed us to assign more than 43 Mb of contigs to sex chromosomes, and to demonstrate extensive recombination and very low divergence between these chromosomes. By taking advantage of multiple F1 families, we delineated a very short genomic region (∼65 kb) that presented no evidence of recombination with the SDR. In this short genomic region, the comparison of sequencing depths between sexes highlighted female-specific genes that have undergone recent duplication, and which may be involved in sex determination in A. vulgare.

Sex chromosomes are highly variable in some taxonomic groups, but the evolutionary mechanisms underlying this diversity are not well understood. In terrestrial isopod crustaceans, evolutionary turnovers in sex chromosomes are frequent, possibly caused by Wolbachia, a vertically-transmitted endosymbiont causing male-to-female sex reversal. Here, we use surgical manipulations and genetic crosses, plus genome sequencing, to examine sex chromosomes in the terrestrial isopod Trachelipus rathkei. Although an earlier cytogenetics study suggested a ZZ/ZW sex chromosome system in this species, we surprisingly find multiple lines of evidence that in our study population, sex is determined by an XX/XY system. Consistent with a recent evolutionary origin for this XX/XY system, the putative male-specific region of the genome is small. The genome shows evidence of Y-linked duplications of the gene encoding the androgenic gland hormone, a major component of male sexual differentiation in isopods. Our analyses also uncover sequences horizontally acquired from past Wolbachia infections, consistent with the hypothesis that Wolbachia may have interfered with the evolution of sex determination in T. rathkei. Overall, these results provide evidence for the co-occurrence of multiple sex chromosome systems within T. rathkei, further highlighting the relevance of terrestrial isopods as models for the study of sex chromosome evolution.

Low coverage genome sequencing is rapid and cost-effective for recovering complete mitochondrial genomes for crustacean phylogenomics. The recovery of high-copy-number nuclear genes, including histone H3, 18S and 28S ribosomal RNAs, is also possible using this approach based on our research with freshwater crayfishes (Astacidea). We explored the potential of genome skimming (GS) to recover additional nuclear genes from shallow sequencing projects using decapod crustaceans. Using an in silico-baited approach, we recovered three additional core histone genes (H2A, H2B, and H4) from our low-coverage decapod dataset (99 species, 69 genera, 38 families, 10 infraorders). Phylogenetic analyses using various combinations of mitochondrial and nuclear genes for the entire decapod dataset and a subset of 40 species of crayfishes showed that the evolutionary rates for different classes of genes varied widely. A very high level of congruence was nevertheless found between trees from the six nuclear genes and those derived from the mitogenome sequences for freshwater crayfish. These findings indicate that nuclear genes recovered from the same genome skimming datasets designed to obtain mitogenomes can be used to support more robust and comprehensive phylogenetic analyses. Further, a search for additional intron-less nuclear genes identified several high-copy-number genes across the decapod dataset, and recovery of NaK, PEPCK, and GAPDH gene fragments is possible at slightly elevated coverage, suggesting the potential and utility of GS in recovering even more nuclear genetic information for phylogenetic studies from these inexpensive and increasingly abundant datasets.

Cities are challenging environments for human life, because of multiple environmental issues driven by urbanization. These can sometimes be mitigated through ecosystem services provided by different functions supported by biodiversity. However, biodiversity in cities is affected by numerous factors, namely habitat loss, degradation, and fragmentation, as well as pollution, altered climate, and new biotic challenges. To better understand the link between biodiversity and ecosystem functions and services, we need to improve our mechanistic knowledge of these relationships. Trait-based ecology is a promising approach for unravelling the causes and consequences of biodiversity filtering on ecosystem processes and underlying services, but large gaps remain unexplored. Here, we present a series of research directions that are aimed at extending the current knowledge of the relationship between trait-based biodiversity and ecosystem functions and services in cities. These directions are based on: (1) improving urban habitat mapping; (2) considering often neglected urban habitats and ecological niches; (3) integrating multiple urban gradients; (4) using trait-based approaches to improve our mechanistic understanding of the relationships between biodiversity and ecosystem functions and services; and (5) extending the involvement of citizens. Pursuing these research directions may support the sustainable management of urban ecosystems and the long-term provision of ecosystem services, ultimately enhancing the well-being of urban populations.(C) 2021 Gesellschaft fur Okologie. Published by Elsevier GmbH. All rights reserved.

The miniature rose-bush architecture may be improved by abiotic stresses applied to plants grown under short cultivation mode, which results in their enhanced robustness, branching and blooming capacity. Miniature rose-bushes of the Meikanrou variety, grown in the annual cycle and submitted to vegetative break during winter (“long” cultivation mode, LCM), developed more solid and branched frame with multiple blooms than those grown in an accelerated 4-month cycle, under constant conditions of light and temperature (“short” cultivation mode, SCM). Plants grown under both cultivation modes displayed significant differences in sugars and amino acids content, pH variations of the vascular sap, as well as modified ATPase proton pumping activity. The main biological question to address was whether abiotic stresses (chemical, mechanical and water), applied under SCM conditions might improve horticultural quality by mimicking those of the LCM plants. Notable cyto-histological modifications were observed in stem vascular tissues of the fourth internode under each of the three abiotic stresses. The chemical stress led to increased syringyl/guaiacyl ratio, and thereby, to cell wall strengthening. The mechanical stress displayed the most pronounced decrease of stem length/diameter ratio, favoring the frame robustness. The most pertinent result concerned the controlled water depletion, which not only appeared able to override the reduced branching under SCM conditions, but also further enhanced it to a level similar to that in plants grown under LCM. The application of the chemical, mechanical and water stresses differentially improved branching, stem fortification and blooming capacity of rose-bushes grown under the SCM conditions, thereby providing promising horticultural applications.

International audience; Actin microfilaments (F‐actin) are major components of the cytoskeleton essential for many cellular dynamic processes (vesicle trafficking, cytoplasmic streaming, organelle movements). The aim of this study was to examine whether cortical actin microfilaments might be implicated in the regulation of nutrient uptake in root and leaf cells of Beta vulgaris. Using antibodies raised against actin and the AtSUC1 sucrose transporter, immunochemical assays demonstrated that the expression of actin and a sucrose transporter showed different characteristics, when detected on plasma membrane vesicles (PMVs) purified from roots and from leaves. The in situ immunolabeling of actin and AtSUC1 sites in PMVs and tissues showed their close proximity to the plasma membrane. Using co‐labeling in protoplasts, actin and sucrose transporters were localized along the internal border and in the outermost part of the plasma membrane, respectively. This respective membrane co‐localization was confirmed on PMVs and in tissues using transmission electronic microscopy. The possible functional role of actin in sucrose uptake (and valine uptake, comparatively) by PMVs and tissues from roots and leaves was examined using the pharmacological inhibitors, cytochalasin B (CB), cytochalasin D (CD), and phalloidin (PH). CB and CD inhibited the sucrose and valine uptake by root tissues in a concentration‐dependent manner above 1 μM, whereas PH had no such effect. Comparatively, the toxins inhibited the sucrose and valine uptake in leaf discs to a lesser extent. The inhibition was not due to a hindering of the proton pumping and H+‐ATPase catalytic activity determined in PMVs incubated in presence of these toxins.

International audience; Mediterranean ecosystems are severely impacted by urbanization, habitat clearing, fires and landscape fragmentation; conservation actions are urgently needed. The protection status of a given area depends notably on the presence and detection rate of protected species. Further, habitat restoration, conservation translocations, or population reinforcement require precise information on the distribution of individuals. Thus, the success of important conservation measures relies on the capacity to locate individuals. Thanks to their sense of smell combined with high learning abilities, dogs have been used to track a wide range of biological targets. They generally surpass humans to detect cryptic species. In this study, we aimed at testing their detection performances with Hermann’s tortoises. This secretive reptile provides a typical case of threatened Mediterranean species where protection actions are hampered by low detection rates; especially because low population densities increase the risk of false negative results during surveys. The ability to detect and save individuals, for example before destructive land-work, might be crucial. We evaluated the detection ability of dogs to find tortoises with two experiments. First, field trials showed that relative detection rate was three times higher in dogs compared to well-trained humans. Then, and more importantly, the absolute detection rate of dogs to find radio tracked tortoises was excellent: after two trials, dogs rapidly located all the experimental tortoises dissimulated along different field transects. Overall, dogs were very efficient in finding tortoises, especially well-hidden individuals. More generally, the immense potential of trained dogs should be extended to improve the techniques to detect and protect Mediterranean reptiles.

International audience; Tryptophan at concentrations higher than 0.1 mM, triggered characteristic early physiological effects such as rapid (within 5 min) dose-dependent membrane hyperpolarization in Mimosa pudica motor cells and modification of the time course of the spontaneous proton efflux monitored in the incubation medium of pulvinar tissues. The rapid modifications of the leaf turgor-mediated movements seen on the primary pulvini of M. pudica following a shock and on Cassia fasciculata leaflets during a transition from light to darkness indicate that tryptophan disturbed the ionic migrations involved in the electrophysiological events and in the osmocontractile reaction of the motor cells. These reactions were specific to tryptophan compared to those induced by serine and 5-hydroxytryptophan. The tryptophan mode of action cannot be linked to a direct modification of the plasma membrane H+-ATPase activity as monitored on purified pulvinar plasma membrane vesicles. The tryptophan metabolism-linked products tryptamine and indole also inhibited the motile reactions, activated in a continuous manner the H+ secretion of pulvinar tissues and showed properties of a protonophore and an ATPase activity inhibitor on plasma membrane vesicles, respectively. The specific behavior of tryptophan in the reaction studies here is discussed in light of the previously reported action of phytohormones.

Atriplex halimus L., endemic to the Mediterranean region and Atriplex canescens (Pursh) Nutt. endemic to the American regions introduced in Algeria are two halophytes of semi-arid to arid regions. Salinity tolerance to NaCl (100, 300 and 600 mM.l-1) of Oran population of halimus L. and El Bayadh population of canescens (Pursh) Nutt. is analyzed. The parameters studied are Na++, K+, Ca++, Mg++ and Cl- . These are studied using two t methods (flame spectrophotometry and microanalysis EDX). In response to NaCl stress, the contents of Ca++ and K+ decrease. However, at low salt concentrations, Ca++ accumulates in the stems and leaves of halimus L. and only in the plant roots of canescens (Pursh) Nutt.. However, the leaves become less and less rich in K+, Mg++ under all salinity treatments in all organs of both species. Na+ accumulates in large amounts in the leaves. However, this accumulation slows down under the effect of salt beyond 300 mM.l-1 in canescens (Pursh) Nutt. while the load in this cation increases in the stems and roots. Therefore, halimus L. is one halophyte of "includer" type whereas canescens (Pursh) Nutt. is "includer" one at concentrations low or equal to 300 mM.l-1. But at 600 mM.l-1, the plant changes to become an"excluder" halophyte. This change in the type can be a way to avoid the harmful effects of stress resulting from ionic salt stress in this species. On the other hand, microanalysis (EDX) shows that the Ca++ and Na+ are two essential elements of halimus L. roots and that only Ca++ is for canescens (Pursh) Nutt.. At the level of leaves, Na+ and Cl- essentially characterize halimus L. However, for plants of canescens (Pursh) Nutt., K+ and Cl- are dominant. Na+ then represents the specific component of the roots and leaves of halimus L. and K+ represents the specific element of canescens (Pursh) Nutt. leaves.

Background Isopods constitute a particular group of crustaceans that has successfully colonized all environments including marine, freshwater and terrestrial habitats. Their ability to use various food sources, especially plant biomass, might be one of the reasons of their successful spread. All isopods, which feed on plants and their by-products, must be capable of lignocellulose degradation. This complex composite is the main component of plants and is therefore an important nutrient source for many living organisms. Its degradation requires a large repertoire of highly specialized Carbohydrate-Active enZymes (called CAZymes) which are produced by the organism itself and in some cases, by its associated microbiota. The acquisition of highly diversified CAZymes could have helped isopods to adapt to their diet and to their environment, especially during land colonization. Results To test this hypothesis, isopod host CAZomes (i.e. the entire CAZyme repertoire) were characterized in marine, freshwater and terrestrial species through a transcriptomic approach. Many CAZymes were identified in 64 isopod transcriptomes, comprising 27 de novo datasets. Our results show that marine, freshwater and terrestrial isopods exhibit different CAZomes, illustrating different strategies for lignocellulose degradation. The analysis of variations of the size of CAZy families shows these are expanded in terrestrial isopods while they are contracted in aquatic isopods; this pattern is probably resulting from the evolution of the host CAZomes during the terrestrial adaptation of isopods. We show that CAZyme gene duplications and horizontal transfers can be involved in adaptive divergence between isopod CAZomes. Conclusions Our characterization of the CAZomes in 64 isopods species provides new insights into the evolutionary processes that enabled isopods to conquer various environments, especially terrestrial ones. Electronic supplementary material The online version of this article (10.1186/s12864-019-5825-8) contains supplementary material, which is available to authorized users.

Microsporidia are obligate intracellular eukaryotic parasites of vertebrates and invertebrates. Microsporidia are usually pathogenic and undergo horizontal transmission or a mix of horizontal and vertical transmission. However, cases of nonpathogenic microsporidia, strictly vertically transmitted from mother to offspring, have been reported in amphipod crustaceans. Some of them further evolved the ability to feminize their nontransmitting male hosts into transmitting females. However, our understanding of the evolution of feminization in microsporidia is hindered by a lack of genomic resources. We report the sequencing and analysis of three strictly vertically transmitted microsporidia species for which feminization induction has been demonstrated (Nosema granulosis) or is strongly suspected (Dictyocoela muelleri and Dictyocoela roeselum), along with a draft genome assembly of their host Gammarus roeselii. Contrary to horizontally transmitted microsporidia that form environmental spores that can be purified, feminizing microsporidia cannot be easily isolated from their host cells. Therefore, we cosequenced symbiont and host genomic DNA and devised a computational strategy to obtain genome assemblies for the different partners. Genomic comparison with feminizing Wolbachia bacterial endosymbionts of isopod crustaceans indicated independent evolution of feminization in microsporidia and Wolbachia at the molecular genetic level. Feminization thus represents a remarkable evolutionary convergence of eukaryotic and prokaryotic microorganisms. Furthermore, a comparative genomics analysis of microsporidia allowed us to identify several candidate genes for feminization, involving functions such as DNA binding and membrane fusion. The genomic resources we generated contribute to establish Gammarus roeselii and its microsporidia symbionts as a new model to study the evolution of symbiont-mediated feminization.

We announce the draft genome sequences of two pathogenic microsporidia of European freshwater crustaceans, Thelohania contejeani (the causative agent of porcelain disease) and Cucumispora dikerogammari. Both species are implicated in mass mortalities in natural populations of their crayfish and amphipod hosts, respectively.

Wolbachia are the most widespread endosymbiotic bacteria in animals. In many arthropod host species, they manipulate reproduction via several mechanisms that favor their maternal transmission to offspring. Among them, cytoplasmic incompatibility (CI) promotes the spread of the symbiont by specifically decreasing the fertility of crosses involving infected males and uninfected females, via embryo mortality. These differences in reproductive efficiency may select for the avoidance of incompatible mating, a process called reinforcement, and thus contribute to population divergence. In the terrestrial isopod Porcellio dilatatus, the Wolbachia wPet strain infecting the subspecies P. d. petiti induces unidirectional CI with uninfected individuals of the subspecies P. d. dilatatus. To study the consequences of CI on P. d. dilatatus and P. d. petiti hybridization, mitochondrial haplotypes and Wolbachia infection dynamics, we used population cages seeded with different proportions of the 2 subspecies in which we monitored these genetic parameters 5 and 7 years after the initial setup. Analysis of microsatellite markers allowed evaluating the degree of hybridization between individuals of the 2 subspecies. These markers revealed an increase in P. d. dilatatus nuclear genetic signature in all mixed cages, reflecting an asymmetry in hybridization. Hybridization led to the introgressive acquisition of Wolbachia and mitochondrial haplotype from P. d. petiti into nuclear genomes dominated by alleles of P. d. dilatatus. We discuss these results with regards to Wolbachia effects on their host (CI and putative fitness cost), and to a possible reinforcement that may have led to assortative mating, as possible factors contributing to the observed results.

Inferring the dispersal processes of vector-borne plant pathogens is a great challenge because the plausible epidemiological scenarios often involve complex spread patterns at multiple scales. The spatial genetic structure of ‘Candidatus Phytoplasma prunorum’, responsible for European stone fruit yellows disease, was investigated by the application of a combination of statistical approaches to genotype data of the pathogen sampled from cultivated and wild compartments in three French Prunus-growing regions. This work revealed that the prevalence of the different genotypes is highly uneven both between regions and compartments. In addition, we identified a significant clustering of similar genotypes within a radius of 50 km or less, but not between nearby wild and cultivated Prunus. We also provide evidence that infected plants are transferred between production areas, and that both species of the Cacopsylla pruni complex can spread the pathogen. Altogether, this work supports a main epidemiological scenario where ‘Ca. P. prunorum’ is endemic in — and generally acquired from — wild Prunus by its immature psyllid vectors. The latter then migrate to shelter plants that epidemiologically connect sites less than 50 km apart by later providing infectious mature psyllids to their “migration basins”. Such multi-scale studies could be useful for other pathosystems.

Inferring the dispersal processes of vector-borne plant pathogens is a great challenge because the plausible epidemiological scenarios often involve complex spread patterns at multiple scales. European stone fruit yellows (ESFY), a disease caused by ‘CandidatusPhytoplasma prunorum’ and disseminated via planting material and vectors belonging to the speciesCacopsylla pruni, is a major threat for stone fruit production throughout Europe. The spatial genetic structure of the pathogen was investigated at multiple scales by the application of a combination of statistical approaches to a large dataset obtained through the intensive sampling of the three ecological compartments hosting the pathogen (psyllids, wild and cultivatedPrunus) in threePrunus-growing regions in France. This work revealed new haplotypes of ‘Ca. P. prunorum’, and showed that the prevalence of the different haplotypes of this pathogen is highly uneven between all regions, and within two of them. In addition, we identified a significant clustering of similar haplotypes within a radius of at most 50 km, but not between nearby wild and cultivatedPrunus. We also provide evidence that the two species of theC. prunicomplex are unevenly distributed but can spread the pathogen, and that infected plants are transferred between production areas. Altogether, this work supports a main epidemiological scenario where ‘Ca. P. prunorum’ is endemic in, and mostly acquired from, wildPrunusby immatureC. pruni(of both species) who then migrate to “shelter plants” that epidemiologically connect sites less than 50 km apart by later providing infectious matureC. prunito their “migration basins”, which differ in their haplotypic composition. We argue that such multiscale studies would be very useful for other pathosystems.

Plants live in close relationships with complex populations of microorganisms, including rhizobacterial species commonly referred to as plant growth-promoting rhizobacteria (PGPR). PGPR are able to improve plant productivity, but the molecular mechanisms involved in this process remain largely unknown. Using an in vitro experimental system, the model plant Arabidopsis thaliana, and the well-characterized PGPR strain Pseudomonas simiae WCS417r (PsWCS417r), we carried out a comprehensive set of phenotypic and gene expression analyses. Our results show that PsWCS417r induces major transcriptional changes in sugar transport and in other key biological processes linked to plant growth, development, and defense. Notably, we identified a set of 13 genes of the SWEET and ERD6-like sugar transporter gene families whose expression is up- or down-regulated in response to seedling root inoculation with the PGPR or exposure to their volatile compounds. Using a reverse genetic approach, we demonstrate that SWEET11 and SWEET12 are functionally involved in the interaction and its plant growth-promoting effects, possibly by controlling the amount of sugar transported from the shoot to the root and to the PGPR. Altogether, our study reveals that PGPR-induced beneficial effects on plant growth and development are associated with changes in plant sugar transport.

International audience; Candida auris is an emerging species responsible for life-threatening infections. Its ability to be resistant to most systemic antifungal classes and its capacity to persist in a hospital environment have led to health concerns. Currently, data about environmental reservoirs are limited but remain essential in control of C. auris spread. The aim of our study was to explore the interactions between C. auris and two free-living amoeba (FLA) species, Vermamoeba vermiformis and Acanthamoeba castellanii, potentially found in the same water environment. Candida auris was incubated with FLA trophozoites or their culture supernatants. The number of FLA and yeasts was determined at different times and transmission electron microscopy (TEM) was performed. Supernatants of FLAs promoted yeast survival and proliferation. Internalization of viable C. auris within both FLA species was also evidenced by TEM. A water environmental reservoir of C. auris can therefore be considered through FLAs and contamination of the hospital water networks would consequently be possible.

The Lesser Antilles, in the Eastern Caribbean, is inhabited by threeIguanaspecies: the Lesser Antillean iguanaIguana delicatissima, which is endemic to the northernmost islands of the Lesser Antilles, the introduced common iguana from South America,Iguana iguana iguana, represented also by the two newly described endemic subspeciesIguana iguana sanctaluciaefrom Saint Lucia andIguana iguana insularisfrom Saint Vincent and the Grenadines, and Grenada, and the introducedIguana rhinolophafrom Central America. Drawing on both morphological and genetic data, this paper describes theIguanapopulations from Saba and Montserrat as a new species,Iguana melanoderma. This species is recognized on the basis of the following combination of characteristics: private microsatellite alleles, unique mitochondrial ND4 haplotypes, a distinctive black spot between the eye and tympanum, a dorsal carpet pattern on juveniles and young adults, a darkening of body coloration with aging (except for the anterior part of the snout), a black dewlap, pink on the jowl, the high number of large tubercular nape scales, fewer than ten medium sized–triangular dewlap spikes, high dorsal spikes, and lack of horns on the snout. This new melanistic taxon is threatened by unsustainable harvesting (including for the pet trade) and both competition and hybridization from escaped or released invasive alien iguanas (I. iguana iguanaandI. rhinolopha) from South and Central America, respectively. The authors call for action to conserveIguana melanodermain Saba and Montserrat and for further research to investigate its relationship to other melanistic iguanas from the Virgin Islands and coastal islands of Venezuela.

Senescence, the decline of physiological parameters with increasing age, is a quasi-ubiquitous phenomenon in the living world. The observed patterns of senescence, however, can markedly differ across species and populations, between sexes, and even among individuals. To identify the drivers of this variation in senescence, experimental approaches are essential and involve the development of tools and new study models. Current knowledge of the senescence process is mostly based on studies on vertebrates and main information about senescence in invertebrates is mostly limited to model organisms such asCaenorhabditis elegansorDrosophila melanogaster. In this context, we tested whether biomarkers of vertebrate ageing could be used to study senescence in a new invertebrate model: the common woodlouseArmadillidium vulgare(Latreille, 1804). More specifically, we looked for the effect of age in woodlouse on three well-established physiological biomarkers of ageing in vertebrates: immune cells (cell size, density, and viability), β-galactosidase activity, and the gene expression of telomerase reverse transcriptase (TERT), an essential subunit of telomerase protein. We found that the size of immune cells was higher in older individuals, whereas their density and viability decreased, and that the β-galactosidase activity increased with age, whereas the TERT gene expression decreased. These findings demonstrate that woodlouse displays age-related changes in biomarkers of vertebrate senescence, with different patterns depending on gender. The tools used in studies of vertebrate senescence can thus be successfully used in studies of senescence of invertebrates such as the woodlouse. The application of commonly used tools to new biological models offers a promising approach to assess the diversity of senescence patterns across the tree of life.

Using the isopod Armadillidium vulgare as a case study, we review the significance of the "bacterial dosage model", which connects the expression of the extended phenotype to the rise of the Wolbachia load. In isopods, the Insulin-like Androgenic Gland hormone (IAG) induces male differentiation: Wolbachia feminizes males through insulin resistance, presumably through defunct insulin receptors. This should prevent an autocrine development of the androgenic glands so that females differentiate instead: feminization should translate as IAG silencing and increased Wolbachia load in the same developmental window. In line with the autocrine model, uninfected males expressed IAG from the first larval stage on, long before the androgenic gland primordia begin to differentiate, and exponentially throughout development. In contrast in infected males, expression fully stopped at stage 4 (juvenile), when male differentiation begins. This co-occurred with the only significant rise in the Wolbachia load throughout the life-stages. Concurrently, the raw expression of the bacterial Secretion Systems co-increased, but they were not over-expressed relative to the number of bacteria. The isopod model leads to formulate the "bacterial dosage model" throughout extended phenotypes as the conjunction between bacterial load as the mode of action, timing of multiplication (pre/post-zygotic), and site of action (soma vs. germen).

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Plants live in association with complex populations of microorganisms, including Plant Growth-Promoting Rhizobacteria (PGPR) that confer to plants an improved growth and enhanced stress tolerance. This large and diverse group includes endophytic bacteria that are able to colonize the internal tissues of plants. In the present study, we have isolated a nonrhizobial species from surface sterilized root nodules of Retama monosperma, a perennial leguminous species growing in poor and high salinity soils. Sequencing of its genome reveals this endophytic bacterium is a Bacillus megaterium strain (RmBm31) that possesses a wide range of genomic features linked to plant growth promotion. Furthermore, we show that RmBm31 is able to increase the biomass and positively modify the root architecture of seedlings of the model plant species Arabidopsis thaliana both in physical contact with its roots and via the production of volatile organic compounds. Lastly, we investigated the molecular mechanisms implicated in RmBm31 plant beneficial effects by carrying out a transcriptional analysis on a comprehensive set of phytohormone-responsive marker genes. Altogether, our results demonstrate that RmBm31 displays plant growth-promoting traits of potential interest for agricultural applications.

Triturus cristatus and Triturus marmoratus are two protected and declining newts occurring in the administrative department of Vienne, in France. They have limited dispersal abilities and rely on the connectivity between habitats and their suitability. In a warming climate, the locations of suitable habitats are expected to change, as is the connectivity. Here, we wondered how climate change might affect shifts in habitat suitability and connectivity of habitat patches, as connectivity is a key element enabling species to realize a potential range shift. We used ecological niche modelling (ENM), combining large-scale climate suitability with local scale, high-resolution habitat features, to identify suitable areas for the two species, under low and high warming scenarios (RCP 2.6 and RCP 8.5). We associated it with connectivity assessment through graph theory. The variable ‘small ponds’ contributed most to land cover-only ENMs for both species. Projections with climate change scenarios revealed a potential impact of warming on suitable habitat patches for newts, especially for T. cristatus. We observed a decrease in connectivity following a decrease in patch suitability. Our results highlight the important areas for newt habitat connectivity within the study area, and define those potentially threatened by climate warming. We provide information for prioritizing sites for acquisition, protection or restoration, and to advise landscape policies. Our framework is a useful and easily reproducible way to combine global climate requirements of the species with detailed information on species habitats and occurrence when available.

In promiscuous mating systems, both males and females mate with several partners. While the benefits of multiple mating are well recognized for males, there are several non-mutually exclusive hypotheses to explain multiple mating for females. Promiscuity is widespread in terrestrial isopods. Here, we placed experimental populations of the terrestrial isopod Armadillidium vulgare under varying sex ratios to manipulate the number of available partners, and better characterise the mating system in this species by performing paternity tests using microsatellite markers. We observed that females usually mate multiply with up to 5 males in a single event of reproduction. A higher number of fathers in broods did not increase brood size nor heterozygosity, but increased allelic richness. Promiscuity seems to be asymmetric in this species, with females being less affected by changes in sex ratio than were males and would be an adaptive mating system maximising the offspring genetic diversity.

International audience; 1. The white-clawed crayfish (Austropotamobius pallipes) is globally endangered due to the impacts of habitat modification and fragmentation, water pollution, climate change, and invasive species, particularly the signal crayfish (Pacifastacus leniusculus). These pressures have caused the decline of A. pallipes populations in Europe, demonstrating the importance of predicting the species' potential distribution under current and future conditions. Focusing on the watercourses of mainland France, we aimed to identify suitable areas for A. pallipes to guide the conservation of current populations and future introduction actions or protection measures.2. We applied ecological niche modelling to model the potential distribution of both A. pallipes and P. leniusculus and identified locations suitable for A. pallipes only. We also assessed the potential distribution of the species under two representative concentration pathway (RCP) scenarios: RCP 2.6 and RCP 8.5, respectively describing low-warming and high-warming conditions.3. We found that A. pallipes and P. leniusculus exploit equivalent niches in France. Despite this, under current conditions, about 5% of the study area simultaneously records a high suitability for A. pallipes and a low suitability for P. leniusculus and is therefore of significant conservation interest. This percentage remains relatively stable under RCP 2.6 for 2050 and 2100, but decreases to 2% under RCP 8.5 for 2100.4. Ecological niche modelling can supply crucial guidance for conservation actions aimed at protecting endangered species at a national scale by identifying sites most suitable for protection and sites where climate change and invasive species constitute a threat.

International audience; Reproductive senescence is the decrease of reproductive performance with in- creasing age and can potentially include trans-generational effects as the offspring produced by old parents might have a lower fitness than those produced by young parents. This negative effect may be caused either by the age of the father, mother or the interaction between the ages of both parents. Using the common woodlouse Armadillidium vulgare, an indeterminate grower, as a biological model, we tested for the existence of a deleterious effect of parental age on fitness components. Contrary to previous findings reported from vertebrate studies, old parents produced both a higher number and larger offspring than young parents. However, their offspring had lower fitness components (by surviving less, producing a smaller number of clutches or not reproducing at all) than offspring born to young parents. Our findings strongly support the existence of trans-generational senescence in woodlice and contradict the belief that old individuals in indeterminate growers contribute the most to re- cruitment and correspond thereby to the key life stage for population dynamics. Our work also provides rare evidence that the trans-generational effect of senescence can be stronger than direct reproductive senescence in indeterminate growers.

International audience; The present study provides an insight on physiological parameters and root-associated microbiome of two complementary Arabidopsis thaliana culture systems suitable for physiological studies. Methods: A. thaliana plants were grown in rhizobox and in classic pot culture. An analysis of plant growth parameters along with the characterization of the bacterial communities of the compost and the rhizosphere, rhizoplane and endosphere compartments were performed. Results: A. thaliana plants grown in rhizobox exhibited a plant habitus similar to those grown in pots during the first month, but with a delayed leaf initiation and slower rate of growth over the experiment. No nutrient deficiency symptoms were observed in these plants. The rhizobox design permits the migration of bacteria from compost to plant roots and allowed root-bacteria interactions to be established as in traditional pot culture. Some differences into the composition of the rhizobiome were highlighted between the two culture systems. Nevertheless, key bacterial taxa that help to ensure plant growth and health colonized the rhizo- and endosphere compartments in both systems. Conclusions: This study gives some clues for future research programs and selection of efficient root systems with the use of such specific culture devices.

Two Fabaceae exhibiting rapid osmocontractile pulvinar movements were used in this study because this activity is modified by natural auxin and dramatically by 2,4D. A short chain with a carboxylic group being required for auxinic properties, a critical point to analyze is whether the recently synthesized proherbicide e-(2,4-dichlorophenoxyacetyl)-L-Lys (2-4D-L-Lys) maintains some biological activity despite the increase in length of the chain and the substitution of the carboxyl group by an α-amino acid function. No trace of 2,4D could be detected in the pulvinar tissues treated for 1 h with 2,4D-L-Lys. Complementary approaches (electrophysiology, pH measurements, use of plasma membrane vesicles) suggest that it was less efficient than 2,4D to activate the plasma membrane H+-ATPase (PM-H+-ATPase). However, it modified the various ion-driven reactions of Mimosa pudica and Cassia fasciculata pulvini in a similar way as 2,4D. Additionally, it was much more effective than fusicoccin to inhibit seismonastic movements of M. pudica leaves and, at low concentrations, to promote leaflet opening in dark, indicating that its mode of action is more complex than the only activation of the PM-H+-ATPase. Various substitutions on 2,4D-L-Lys affected its activity in correlation with the molecular descriptor “halogen ratio” of these derivatives. Conjugation with D-Lys also led to a decrease of pulvinar reaction, suggesting that 2,4D-Lys maintains the main signaling properties of 2,4D involved in pulvinar movements providing that the terminal zwitterion is in a suitable orientation. Our data guide future investigations on the effect of 2,4D and 2,4D-L-Lys on the vacuolar pump activity of motor cells.

The subfamily GH13_1 of alpha-amylases is typical of Fungi, but it is also found in some unicellular eukaryotes (e.g., Amoebozoa, choanoflagellates) and non-bilaterian Metazoa. Since a previous study in 2007, GH13_1 amylases were considered ancestral to the Unikonts, including animals, except Bilateria, such that it was thought to have been lost in the ancestor of this clade. The only alpha-amylases known to be present in Bilateria so far belong to the GH13_15 and 24 subfamilies (commonly called bilaterian alpha-amylases) and were likely acquired by horizontal transfer from a proteobacterium. The taxonomic scope of Eukaryota genomes in databases has been greatly increased ever since 2007. We have surveyed GH13_1 sequences in recent data from ca. 1600 bilaterian species, 60 non-bilaterian animals and also in unicellular eukaryotes. As expected, we found a number of those sequences in non-bilaterians: Anthozoa (Cnidaria) and in sponges, confirming the previous observations, but none in jellyfishes and in Ctenophora. Our main and unexpected finding is that such fungal (also called Dictyo-type) amylases were also consistently retrieved in several bilaterian phyla: hemichordates (deuterostomes), brachiopods and related phyla, some molluscs and some annelids (protostomes). We discuss evolutionary hypotheses possibly explaining the scattered distribution of GH13_1 across bilaterians, namely, the retention of the ancestral gene in those phyla only and/or horizontal transfers from non-bilaterian donors.

Background The recently published complete mitogenome of the European lobster (Homarus gammarus) that was generated using long-range PCR exhibits unusual gene composition (missing nad2) and gene rearrangements among decapod crustaceans with strong implications in crustacean phylogenetics. Such atypical mitochondrial features will benefit greatly from validation with emerging long read sequencing technologies such as Oxford Nanopore that can more accurately identify structural variation. Results We re-sequenced the H. gammarus mitogenome on an Oxford Nanopore Minion flowcell and performed a long-read only assembly, generating a complete mitogenome assembly for H. gammarus. In contrast to previous reporting, we found an intact mitochondrial nad2 gene in the H. gammarus mitogenome and showed that its gene organization is broadly similar to that of the American lobster (H. americanus) except for the presence of a large tandemly duplicated region with evidence of pseudogenization in one of each duplicated protein-coding genes. Conclusions Using the European lobster as an example, we demonstrate the value of Oxford Nanopore long read technology in resolving problematic mitogenome assemblies. The increasing accessibility of Oxford Nanopore technology will make it an attractive and useful tool for evolutionary biologists to verify new and existing unusual mitochondrial gene rearrangements recovered using first and second generation sequencing technologies, particularly those used to make phylogenetic inferences of evolutionary scenarios. Electronic supplementary material The online version of this article (10.1186/s12864-019-5704-3) contains supplementary material, which is available to authorized users.

International audience; Biological invasions have reached an unprecedented level and the number of introduced species is still increasing worldwide. Despite major advances in invasion science, the determinants of success of introduced species, the magnitude and dimensions of their impact, and the mechanisms sustaining successful invasions are still debated. Empirical studies show divergent impacts of nonnativepopulations on ecosystems and contrasting effects of biotic and abiotic factors on the dynamics of non-native populations; this is hindering the emergence of a unified theory of biological invasions. We propose a synthesis that merges perspectives from population, community, and ecosystem levels. Along a timeline of ecosystem transformation driven by nonnative species, from historical to human-modified ecosystems, we order invasion concepts and theories to clarify their chaining and relevance during each step of the invasion process. This temporal sorting of invasion concepts shows that each concept is relevant at a specific stage of theinvasion. Concepts and empirical findings on non-native species may appear contradictory. However, we suggest that, when mapped onto an invasion timeline, they may be combined in a complementary way. An overall scheme is proposed to summarise the theoretical dynamics of ecosystems subjected to invasions. For any given case study, this framework provides a guide through the maze of theories and should help choose the appropriate concepts according to the stage of invasion.

The organization of the genome into transcriptionally active and inactive chromatin domains requires well-delineated chromatin boundaries and insulator functions in order to maintain the identity of adjacent genomic loci with antagonistic chromatin marks and functionality. In plants that lack known chromatin insulators, the mechanisms that prevent heterochromatin spreading into euchromatin remain to be identified. Here, we show that DNA Topoisomerase VI participates in a chromatin boundary function that safeguards the expression of genes in euchromatin islands within silenced heterochromatin regions. While some transposable elements are reactivated in mutants of the Topoisomerase VI complex, genes insulated in euchromatin islands within heterochromatic regions of theArabidopsis thalianagenome are specifically downregulated. H3K9me2 levels consistently increase at euchromatin island loci and decrease at some TE loci. We further show that Topoisomerase VI physically interacts with S-adenosylmethionine (SAM) synthase MAT3, which is required for H3K9me2 deposition. Topoisomerase VI promotes MAT3 occupancy on heterochromatic elements and its exclusion from euchromatic islands, thereby providing a mechanistic insight into the essential role of Topoisomerase VI in the delimitation of chromatin domains.

International audience; In the terrestrial crustacean Armadillidium vulgare, a large size range exists in natural populations within which males and females could potentially mate. Because of continuous growth far beyond sexual maturity, the largest individuals can be nearly ten times the live mass of the smallest sexually mature individuals. In this study, we explored the influence of male and female body mass on the mating behaviour and success. Starting with a representative panel of males and females in which females are significantly larger than males in average, we followed the sexual behaviour of 23 groups of 20 mixed-sex virgin animals under conditions comparable with natural field situation during the early breeding season. We found a correlation between paired individuals showing an assortative pairing. During pairing male stimulates female and duration of stimulation is determinant for pairing follow-up: efficient stimulation is correlated with female size and not with male size. In consequence , pairs in mating show a reversed size dimorphism between male and female where female are about 20% smaller. Largest females were not mated. During copulation behaviour, the quantity of sperm transferred is positively correlated with copulation duration. Stored sperm can be used for immediate breeding by the female and stored in the spermatheca for future breeding. The last option allows to largest females in the field to continue breeding without additional mating, avoiding the lack of availability of large males able to stimulate them efficiently.

International audience; Whereas the effects of climate change on the potential range shifts of amphibians have been modeled at various scales, exploring the future impacts of land-use changes has rarely been considered. We modeled the potential distribution of Bombina variegata, Hyla arborea, Hyla meridionalis, and Triturus cristatus using ecological niche modeling, in the French administrative region Nouvelle-Aquitaine. The species are all at range margin in the study area which makes them interesting model species to study range shifts because of their potential local adaptations to their marginal habitat. We used Dyna-CLUE modeling framework to produce land-use change scenarios and combined them with RCP 2.6 and RCP 8.5 climate change scenarios to predict their impact on local amphibian distributions. B. variegata, H. arborea, and T. cristatus were predicted to shift eastward and northward. H. meridionalis was predicted to increase its probability of presence in the study area. The effect of climate determined the general pattern of distribution and was modulated depending on the scenarios of land-use change.

International audience; Fungal communities associated to three epiphytic lichens active against Candida, were investigated using culture-based methods We hypothetized that associated fungi would contribute to lichens activities. The ability of specific fungi to grow inside or outside lichens was investigated. To detect biogenesis pathways involved in the production of secondary metabolites, genes coding for nonribosomal peptide synthetase (NRPS) and polyketide synthase I (PKS I) were screened by PCR from fungal DNA extracts. Both endo and epilichenic communities were isolated from two fructicose (Evernia prunastri and Ramalina fastigiata) and one foliose (Pleurosticta acetabulum) lichens. A total of 86 endolichenic and 114 epilichenic isolates were obtained, corresponding to 18 and 24 phylogenetic groups respectively suggesting a wide diversity of fungi. The communities and the species richness were distinct between the three lichens which hosted potentially new fungal species. Additionally, the endo- and epilichenic communities differed in their composition: Sordariomycetes were particularly abundant among endolichenic fungi and Dothideomycetes among epilichenic fungi. Only a few fungi colonized both habitats, such as S. fimicola, Cladosporium sp1 and Botrytis cinerea. Interestingly, Nemania serpens (with several genotypes) was the most abundant endolichenic fungus (53% of isolates) and was shared by the three lichens. Finally, 12 out of 36 phylogenetic groups revealed the presence of genes coding for nonribosomal peptide synthetase (NRPs) and polyketide synthase I (PKS I). This study shows that common lichens are reservoirs of diverse fungal communities, which could potentially contribute to global activity of the lichen and, therefore, deserve to be isolated for further chemical studies.

Genetic diversity is known to be correlated to fitness traits, and inbred individuals often display lower values for life history traits. In this study, we attempt to quantify how inbreeding affects such traits in the terrestrial isopod Armadillidium vulgare by performing inbred and non-inbred crosses under laboratory conditions. We estimated genetic characteristics of parents and offspring, and related them to fecundity and fertility measures, as well as offspring growth and survival. Our study shows that a decrease in offspring number might result from mortality around birth, but not to changes in fecundity, fertilization rate, or developmental failure between inbred and non-inbred crosses. More heterozygous females tended to be bigger and had a higher fecundity, which could have implications in mate choice. No effect of inbreeding was detected on offspring growth and survival. These results can be related to previously observed effects of genetic characteristics on mating strategies in A. vulgare, and could shed light on mechanisms of inbreeding avoidance in this species.

The signal crayfish Pacifastacus leniusculus, native to northwestern North America, has become the most widespread invasive crayfish species in Europe. It has been introduced repeatedly since 1959, and altogether >60,000 individuals were imported. Secondary introductions across the continent followed, resulting in its current presence in ≥26 European countries. Recent studies indicate that multiple highly divergent lineages of signal crayfish exist in its North American range, and previous investigators have suggested that >1 signal crayfish subspecies are present in Europe. We investigated its genetic variation by sequencing a fragment of the mitochondrial gene for cytochrome c oxidase subunit I (COI) to clarify the diversity of this invasive species in its European range. We analyzed 348 signal crayfish from 68 European populations and compared the resulting patterns with reference sequences from North America. All European individuals studied fell within 1 clade of P. leniusculus, but we observ...

Austropotamobius pallipes is an endangered decapod attracting much attention in freshwater conservation programmes. In some cases population transfers or reintroductions are carried out in lentic ecosystems such as ponds or quarries. Such conservation actions require rapid, low cost and powerful tools to census suitable habitat. Some species of the Characeae family (Chara spp.), share ecological needs with A. pallipes and are proposed as bioindicators of suitable habitat. Chara species were tested, among other plants, as bioindicators, and to see whether Chara species are a stronger indicator than water chemistry. The Pinail Nature Reserve, with 3000 permanent ponds, is inhabited by white-clawed crayfish probably introduced historically into ponds used for fish production. This allows a replicated study of suitable habitats where plant communities are bioindicators of crayfish presence. Crayfish presence is associated with Chara species (such as Chara aspera, Chara virgata, Chara fragifera, Chara polyacantha and Chara vulgaris). Austropotamobius pallipes is present in ponds with Chara spp. (N = 10/10) while other ponds without crayfish are lacking charophytes (N = 1/23). Algae of the genus Chara are thus a simple and low-cost additional tool for determining suitable habitat for crayfish introductions within enclosed waters protected from exotic invasive species and disease. Cladium mariscus also appears to be another useful bioindicator for crayfish habitat.

The highly compact mitochondrial (mt) genome of terrestrial isopods (Oniscidae) presents two unusual features. First, several loci can individually encode two tRNAs, thanks to single nucleotide polymorphisms at anticodon sites. Within-individual variation (heteroplasmy) at these loci is thought to have been maintained for millions of years because individuals that do not carry all tRNA genes die, resulting in strong balancing selection. Second, the oniscid mtDNA genome comes in two conformations: a ∼14 kb linear monomer and a ∼28 kb circular dimer comprising two monomer units fused in palindrome. We hypothesized that heteroplasmy actually results from two genome units of the same dimeric molecule carrying different tRNA genes at mirrored loci. This hypothesis, however, contradicts the earlier proposition that dimeric molecules result from the replication of linear monomers—a process that should yield totally identical genome units within a dimer. To solve this contradiction, we used the SMRT (PacBio) technology to sequence mirrored tRNA loci in single dimeric molecules. We show that dimers do present different tRNA genes at mirrored loci; thus covalent linkage, rather than balancing selection, maintains vital variation at anticodons. We also leveraged unique features of the SMRT technology to detect linear monomers closed by hairpins and carrying noncomplementary bases at anticodons. These molecules contain the necessary information to encode two tRNAs at the same locus, and suggest new mechanisms of transition between linear and circular mtDNA. Overall, our analyses clarify the evolution of an atypical mt genome where dimerization counterintuitively enabled further mtDNA compaction.