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The strong linkages between disaster risk reduction and the environment are well-acknowledged, and are magnified by the impacts of climate change on the severity and frequency of environmental disasters (landslides, floods, storm surges, forest fires, etc). Most of the time, ecosystems themselves can offer sustainable solutions for the reduction of disaster risks and the severity of their impacts, while adapting to global changes. Nature-Based Solutions, Ecosystem-based Adaptation, Green Infrastructure and Natural Water Retention Measures are examples of ecosystem-based initiatives that have been promoted by the European Commission to address a variety of policy goals. In this context, ecosystem-based approaches for Disaster Risk Reduction aim at improving the condition and resilience of ecosystems in urban, rural and wilderness areas and as such, contribute to implementing the new Sendai Framework for Disaster Risk Reduction 2015–2030, while also contributing to achieving other policy objectives - from biodiversity conservation to climate change adaptation. The European Commission has also been actively engaging the research community to better address disaster risk management knowledge and technology gaps through its Research and Innovation strategy and Framework Programmes, notably Horizon 2020. Research has shown that ecosystem-based approaches are often cost-effective and provide a wide range of co-benefits for local and regional economies, social cohesion and the broader environment. Fostering green growth through promoting risk-proofed investments and building the capacity of local, regional and national authorities and communities is a priority of the EU Action Plan for Disaster Risk Reduction, which sets the basis for a disaster-risk-informed approach to policy making at EU level.

International audience; As phytohormones lie at the very core of molecular mechanisms controlling the plant physiology and development, they have long been hypothesized to be involved in insect-induced plant manipulations. Cytokinins (CKs) are phytohormones now widely recognized to be utilized by leaf-mining and gall-inducing insects in the control of the physiology of their host plant. In some leaf-mining moth species, larvae can supply the hormones themselves, bacterial symbionts contributing to the production of CKs. Our objective was to investigate whether closely related leaf-miner species sharing the same ecological niche but differing in their Wolbachia infection status develop similar strategies to manipulate their host plant. An extensive identification and quantification of CKs has been used to elucidate physiological patterns relevant for the plant-insect interactions. Our results show that modulation of plant CK levels is impaired in the Wolbachia-free leaf-mining moth Phyllonoryc-ter mespilella (H€ ubner) (Lepidoptera: Gracillariidae) contrasting with results previously observed in the closely related moth species Phyllonorycter blancardella (Fabricius) that produce and deliver CKs to the plant through an intricate interaction with Wolbachia. Our study suggests that mechanisms underlying colonization of the host plant and adaptation to fluctuating environmental conditions are different between the two leaf-miner species and that P. mespilella larvae most likely do not produce CKs. This species rather only buffers the degradation of CKs naturally occurring during the senescence of leaves leading to few active CKs being maintained at a sufficiently high level to induce and maintain a 'green island' phenotype (photosynthetically active green patches in otherwise senescing leaves). This study further provides converging experimental evidence pointing toward the influence of bacterial symbionts in the ability of leaf-mining moths to control the physiology of their host plant with consequences for their ecology and evolutionary diversification.

Contemporary societies are facing a broad range of challenges, from pressures on human health and well-being to natural capital depletion, and the security of food, water and energy. These challenges are deeply intertwined with global processes, such as climate change and with local events such as natural disasters. The EU's research & innovation (R&I) policy is now seeking to address these challenges from a new perspective, with Nature-Based Solutions, and turn them into innovation opportunities that optimise the synergies between nature, society and the economy. Nature-Based Solutions can be an opportunity for innovation, and are here promoted by both policymakers and practitioners as a cost-effective way of creating a greener, more sustainable, and more competitive economy. Since 2013, the European Commission has devoted particular attention to Nature-Based Solutions through consultations and dialogues that sought to make the concept of these solutions more concrete and to define the concept's place within the spectrum of ecosystem-based approaches. In 2014, the Commission launched an expert group, which conducted further analysis, and made recommendations to help increase the use of Nature-Based Solutions and bring nature back into cities. In 2015, a survey was conducted on citizens' views and perceptions of 'Nature in Cities' to provide further insight for future work. Based on these elements and on results from running EU projects, the Commission has developed an R&I agenda for Nature-Based Solutions and has published targeted calls for proposals for large-scale demonstration projects in this field in 2016 and 2017. Additional R&I actions at EU level that promote systemic Nature-Based Solutions and their benefits to cities and territories are planned with the aim to improve the implementation capacity and evidence base for deploying Nature-Based Solutions and developing corresponding future markets. They are also expected to foster an interdisciplinary R&I and stakeholder community and the exchange of good practices in this field, as well as help shaping and implementing international R&I agendas on Nature-Based Solutions.

International audience; The fixation probability of a recessive beneficial mutation is increased on the X or Z chromosome, relative to autosomes, because recessive alleles carried by X or Z are exposed to selection in the heterogametic sex. This leads to an increased dN/dS ratio on sex chromosomes relative to autosomes, a pattern called the "fast-X" or "fast-Z" effect. Besides positive selection, the strength of genetic drift and the efficacy of purifying selection, which affect the rate of molecular evolution, might differ between sex chromosomes and autosomes. Disentangling the complex effects of these distinct forces requires the genome-wide analysis of polymor-phism, divergence and gene expression data in a variety of taxa. Here we study the influence of hemizygosity of the Z chromosome in Maniola jurtina and Pyronia tithonus, two species of butterflies (Lepidoptera, Nymphalidae, Satyrinae). Using transcriptome data, we compare the strength of positive and negative selection between Z and autosomes accounting for sex-specific gene expression. We show that M. jurtina and P. tithonus do not experience a faster, but rather a slightly slower evolutionary rate on the Z than on autosomes. Our analysis failed to detect a significant difference in adaptive evolutionary rate between Z and autosomes, but comparison of male-biased, unbiased and female-biased Z-linked genes revealed an increased efficacy of purifying selection against recessive deleterious mutations in female-biased Z-linked genes. This probably contributes to the lack of fast-Z evolution of satyrines. We suggest that the effect of hemizygosity on the fate of recessive deleterious mutations should be taken into account when interpreting patterns of molecular evolution in sex chromosomes vs. autosomes.

Ecosystem-based management advocates that forestry disturbances should aim to emulate natural disturbances to mitigate the landscape-level impact of forest management. This study compares the impact of clear-cuts followed by a prescribed burn (CCPB) with clear-cuts alone (CC) and current careful logging practices (CLAAG: “careful logging around advanced growth”) on understory composition within black spruce (Picea mariana Miller (BSP)) paludified forest stands at the plot, site, and treatment levels using a functional-type approach. Vascular and nonvascular taxa showed significant differences in composition at the plot level among treatments. We found that pioneer taxa occurred mainly in CCPB sites, while late-successional taxa characterized CC sites. CLAAG sites had higher taxa richness than CCPB and CC sites, and we found that CCPB treatments were most likely to promote vascular taxa compositions that are more similar to those observed after natural disturbances. Additionally, the relative abundance of Sphagnum spp., responsible for paludification, was significantly reduced in sites treated by prescribed burning. This study therefore presents results suggesting that prescribed burning might represent a sustainable alternative to current harvesting techniques in the Clay Belt of eastern Canada that could help in preserving biodiversity (in terms of understory species assemblage) while maintaining or even enhancing forest productivity.

Genome-scale diversity data are increasingly available in a variety of biological systems, and can be used to reconstruct the past evolutionary history of species divergence. However, extracting the full demographic information from these data is not trivial, and requires inferential methods that account for the diversity of coalescent histories throughout the genome. Here, we evaluate the potential and limitations of one such approach. We reexamine a well-known system of mussel sister species, using the joint site frequency spectrum (jSFS) of synonymous mutations computed either from exome capture or RNA-seq, in an Approximate Bayesian Computation (ABC) framework. We first assess the best sampling strategy (number of: individuals, loci, and bins in the jSFS), and show that model selection is robust to variation in the number of individuals and loci. In contrast, different binning choices when summarizing the joint site frequency spectrum, strongly affect the results: including classes of low and high frequency shared polymorphisms can more effectively reveal recent migration events. We then take advantage of the flexibility of ABC to compare more realistic models of speciation, including variation in migration rates through time (i.e. periodic connectivity) and across genes (i.e. genome-wide heterogeneity in migration rates). We show that these models were consistently selected as the most probable, suggesting that mussels have experienced a complex history of gene flow during divergence and that the species boundary is semi-permeable. Our work provides a comprehensive evaluation of ABC demographic inference in mussels based on the coding site frequency spectrum, and supplies guidelines for employing different sequencing techniques and sampling strategies. We emphasize, perhaps surprisingly, that inferences are less limited by the volume of data, than by the way in which they are analyzed.

International audience; Alexandrium catenella (group IV) and Alexandrium tamarense (group III) (Dinophyceae) are two cryptic invasive phytoplankton species belonging to the A. tamarense species complex. Their worldwide spread is favored by the human activities, transportation and climate change. In order to describe their diversity in the Mediterranean Sea and understand their settlements and maintenances in this area, new microsatellite markers were developed based on Thau lagoon (France) samples of A. catenella and A. tamarense strains. In this study twelve new microsatellite markers are proposed. Five of these microsatellite markers show amplifications on A. tamarense and ten on A. catenella. Three of these 12 microsatellite markers allowed amplifications on both cryptic species. Finally, the haplotypic diversity ranged from 0.000 to 0.791 and 0.000 to 0.942 for A. catenella and A. tamarense respectively.

AGAP : GE2pop - Génomique évolutive et gestion des populations; International audience; Whether species can respond evolutionarily to current climate change is crucial for the persistence of many species. Yet, very few studies have examined genetic responses to climate change in manipulated experiments carried out in natural field conditions. We examined the evolutionary response to climate change in a common annelid worm using a controlled replicated experiment where climatic conditions were manipulated in a natural setting. Analyzing the transcribed genome of 15 local populations, we found that about 12% of the genetic polymorphisms exhibit differences in allele frequencies associated to changes in soil temperature and soil moisture. This shows an evolutionary response to realistic climate change happening over short-time scale, and calls for incorporating evolution into models predicting future response of species to climate change. It also shows that designed climate change experiments coupled with genome sequencing offer great potential to test for the occurrence (or lack) of an evolutionary response.

Spatial patterns and controls on burned area for two contrasting fire regimes in Southern California N. R. Faivre, 1, † Y. Jin, 2 M. L. Goulden, 1 and J. T. Randerson 1 1 Department 2 Department of Earth System Science, University of California, Irvine, California 92697-3100 USA of Land, Air and Water Resources, University of California, Davis, California 95616-8627 USA Citation: Faivre, N. R., Y. Jin, M. L. Goulden, and J. T. Randerson. 2016. Spatial patterns and controls on burned area for two contrasting fire regimes in Southern California. Ecosphere 7(5):e01210. 10.1002/ecs2.1210 Abstract. An improved understanding of the mechanisms that regulate wildfire risk at local to regional scales is needed for the design of effective fire and ecosystem management. We investigated the spatial distribution of burned area in Southern California during 1960–2009 using five different data-­driven meth- ods: multiple linear regression, generalized additive models (GAMs), GAMs with spatial autocorrelation, non-­linear multiplicative models, and random forest models. We used each method to separately develop burned area risk maps for Southern California’s two distinct wildfire regimes: Santa Ana (SA fires), which occur during high wind events mostly in autumn, and non-­Santa Ana fires (non-­SA fires), which occur mostly during the hot and dry Mediterranean-­climate summer. The different methods explained 38–63% of the spatial variance in burned area for SA fires and 21–48% for non-­SA fires. The two fire regimes had contrasting drivers, with Fosberg fire weather index, relative humidity, minimum temperature, and dis- tance to housing most important for SA fires, and shrub cover, road density, and distance to minor and major roads most important for non-­SA fires. Our modeling framework carries implications for the strate- gic placement of fire suppression resources, and for prevention planning in areas facing increasing human and climate pressures. Key words: biophysical drivers; fire frequency; geospatial regression models; human influence; Mediterranean ­ecosystems; Santa Ana fires; wildfire risk; wildland–urban interface. Received 22 July 2015; accepted 29 July 2015. Corresponding Editor: D. P. C. Peters. Copyright: © 2016 Faivre et al. This is an open access article under the terms of the Creative Commons Attribution ­License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. † E-mail: belotte.faivre@gmail.com I ntroduction loss and multiple fatalities (Brillinger et al. 2009, Keeley et al. 2009). Spatial and temporal variabil- ity in burned area within the region depends on ignition, meteorology, vegetation characteristics, topography, and fire suppression (Davis and Mi- chaelsen 1995, Zedler and Seiger 2000, Moritz et al. 2004). Large areas of wildland–urban inter- face further contribute to variability in burned area as a consequence of ignition probability, landscape fragmentation, and access points for suppression. Interactions between the envi- ronmental and human controls on wildfire are Southern California is prone to recurrent wild- land fire that strongly influences ecosystem pro- cesses and vegetation dynamics. Over the past 50 yr, an average of 40 large fires (>40 ha each) occurred each year, resulting in a mean burned area of 53 300 ha per yr (Jin et al. 2014). Despite considerable investment in fire suppression, fire perimeter data sets show an increasing trend in burned area since 1980 (Westerling 2006, Jin et al. 2014). These fires have caused extensive property v www.esajournals.org May 2016 v Volume 7(5) v Article e01210

Summary Termite gut flagellates are colonized by host-specific lineages of ectosymbiotic and endosymbiotic bacte- ria. Previous studies have shown that flagellates of the genus Trichonympha may harbour more than one type of symbiont. Using a comprehensive approach that combined cloning of SSU rRNA genes with fluo- rescence in situ hybridization and electron micros- copy, we investigated the phylogeny and subcellular locations of the symbionts in a variety of Trichonym- pha species from different termites. The flagellates in Trichonympha Cluster I were the only species asso- ciated with 'Endomicrobia', which were located in the posterior part of the cell, confirming previous results. Trichonympha species of Cluster II from the termite genus Incisitermes (family Kalotermitidae) lacked 'Endomicrobia' and were associated with endo- symbiotic Actinobacteria, which is highly unusual. The endosymbionts, for which we suggest the name 'Candidatus Ancillula trichonymphae', represent a novel, deep-branching lineage in the Micrococcineae that consists exclusively of clones from termite guts. They preferentially colonized the anterior part of the flagellate host and were highly abundant in all species of Trichonympha Cluster II except Tricho- nympha globulosa. Here, they were outnumbered by a Desulfovibrio species associated with the cytoplas- mic lamellae at the anterior cell pole. Such symbionts are present in both Trichonympha clusters, but not in all species. Unlike the intracellular location reported for the Desulfovibrio symbionts of Trichonympha agilis (Cluster I), the Desulfovibrio symbionts of T. globulosa (Cluster II) were situated in deep invagi- nations of the plasma membrane that were clearly connected to the exterior of the host cell.

Landscape pyrodiversity encapsulates the range of spatiotemporal variability in disturbance by fire. There is a widely-held view that diversity in fire regimes promotes biological diversity (i.e., the Pyrodiversity–Biodiversity paradigm). However, this relationship needs to be examined more carefully as pyrodiversity at the landscape scale remains poorly defined and difficult to quantify. Here, we used a novel approach to analyze landscape pyrodiversity by selecting and quantifying appropriate descriptors of fire variability at the landscape level. We characterized and classified observed fire mosaics at the 1 km scale using temporal attributes (fire frequency, time-since-fire and mean fire interval) and a variety of spatial attributes derived from landscape metrics. We trialed our approach on a 50-year record of fire patterns in two Mediterranean environments; (1) in southern France where fire regimes are dominated by unplanned (‘wild’-)fires and (2) in south-west Australia, where fire regimes are dominated by planned fires. We found that the landscape pyrodiversity of both regions was expressed by distinct gradients of both fire frequency and spatial diversity of fire patterns. As expected, the two environments were significantly different in landscape pyrodiversity, with contrasting mean fire frequency and mean time-since-fire patterns. However, we also found similarities between southern France and south-west Australia in the composition and configuration of their spatial fire patterns. Our results show that these two Mediterranean environments form a pyrodiversity continuum despite the disparate management regimes. Our findings also demonstrate that a quantitative characterization of pyrodiversity is central to developing new perspectives and practical tools for biodiversity conservation in fire-prone landscapes.

Summary Endomicrobia represent a candidate class in the Elusimicrobia phylum (formerly Termite Group 1) and were originally described as obligate intracellular symbionts of gut flagellates in lower termites. However, 16S rRNA gene sequences of Endomicrobia have been detected also in the gut of insects that do not possess such flagellates, e.g. higher termites and cockroaches. When we eliminated the large gut flagellates of Reticulitermes santonensis by feeding a starch diet, we discovered novel lineages of Endomicrobia that were hitherto undetected in normally faunated specimens. The new phylotypes are clearly separated from the endosymbionts of gut flagellates and fall into the radiation of those from flagellate-free insects. Comprehensive phylogenetic analysis documented that Endomicrobia comprise an apical cluster of endosymbionts that is not necessarily monophyletic and several apparently basal lineages that include bacteria present in the gut of defaunated lower termites, the naturally flagellate-free guts of higher termites and scarab beetle larvae, and in the cow rumen. We propose that these lineages represent hitherto undetected free-living Endomicrobia that share a common ancestor with the intracellular symbionts.

International audience; Genetic diversity is the amount of variation observed between DNA sequences from distinct individuals of a given species. This pivotal concept of population genetics has implications for species health, domest-ication, management and conservation. Levels of genetic diversity seem to vary greatly in natural populations and species, but the determinants of this variation, and particularly the relative influences of species biology and ecology versus population history, are still largely mysterious 1,2. Here we show that the diversity of a species is predictable , and is determined in the first place by its ecological strategy. We investigated the genome-wide diversity of 76 non-model animal species by sequencing the transcriptome of two to ten individuals in each species. The distribution of genetic diversity between species revealed no detectable influence of geographic range or invasive status but was accurately predicted by key species traits related to parental investment: long-lived or low-fecundity species with brooding ability were genetically less diverse than short-lived or highly fecund ones. Our analysis demonstrates the influence of long-term life-history strategies on species response to short-term environmental perturbations, a result with immediate implications for conservation policies. Since the early studies of evolutionary genetics, there has been no understanding of how and why genetic diversity levels vary between species. This old puzzle, considered four decades ago as 'the central problem in population genetics'

Wildfireignitionrequiresacombinationofanopenspark,andsuitableweatherandfuelconditions.Modelsof fire occurrence and burned area provide a good understanding of the physical and climatic factors that constrain and promote fire spread and recurrence, but information on how humans influence ignition patterns is still lacking at a scale compatible with integrated fire management.We investigated the relative importance of the physical, climatic andhuman factors regulating ignition probability across Southern California's National Forests. A 30-year exploratory analysis of one-way relationships indicated that distance to a road, distance to housing and topographic slope were the major determinants of ignition frequency. We used logistic and Poisson regression analyses to model ignition occurrence and frequency as a function of the dominant covariates. The resulting models explained ,70% of the spatial variability in ignition likelihood and 45% of the variability in ignition frequency. In turn, predicted ignition probability contributed to some of the spatial variability in burned area, particularly for summer fires. These models may enable estimates of fire ignition risk for the broader domain of Southern California and how this risk may change with future population and housing development. Our spatially explicit predictions may also be useful for strategic fire management in the region. Additional keywords: biophysical drivers, fire frequency, fire ignition, human influence, Mediterranean ecosystems, spatial regression model, wildland fire risk.

International audience; The black-chinned tilapia Sarotherodon melanotheron heudelotii is an ecologically appealing model as it showsexceptional adaptive capacities, especially with regard to salinity. In spite of this, this species is devoid of genomicresources, which impedes the understanding of such remarkable features. De novo assembly of transcript sequencesproduced by next-generation sequencing technologies offers a rapid approach to obtain expressed gene sequencesfor non-model organisms. It also facilitates the development of quantitative real-time PCR (qPCR) assays foranalysing gene expression under different environmental conditions. Nevertheless, obtaining accurate and reliableqPCR results from such data requires a number of validations prior to interpretation. The transcriptome of S. melanotheronwas sequenced to discover transcripts potentially involved in the plasticity of male reproduction in responseto salinity variations. A set of 54 candidate and reference genes was selected through a digital gene expression (DGE)approach, and a de novo qPCR assay using these genes was validated for further detailed expression analyses. Auser-friendly web interface was created for easy handling of the sequence data. This sequence collection represents amajor transcriptomic resource for S. melanotheron and will provide a useful tool for functional genomics andgenetics studies.Keywords: gene expression

International audience; The evolution of reproductive division of labour and social life in social insects has lead to the emergence of several life-history traits and adapta-tions typical of larger organisms: social insect colonies can reach masses of several kilograms, they start reproducing only when they are several years old, and can live for decades. These features and the monopolization of reproduction by only one or few individuals in a colony should affect molecular evolution by reducing the effective population size. We tested this prediction by analysing genome-wide patterns of coding sequence polymor-phism and divergence in eusocial vs. noneusocial insects based on newly generated RNA-seq data. We report very low amounts of genetic polymor-phism and an elevated ratio of nonsynonymous to synonymous changes – a marker of the effective population size – in four distinct species of eusocial insects, which were more similar to vertebrates than to solitary insects regarding molecular evolutionary processes. Moreover, the ratio of nonsyn-onymous to synonymous substitutions was positively correlated with the level of social complexity across ant species. These results are fully consistent with the hypothesis of a reduced effective population size and an increased genetic load in eusocial insects, indicating that the evolution of social life has important consequences at both the genomic and population levels.

Endomicrobia represent a candidate class in the Elusimicrobia phylum (formerly Termite Group 1) and were originally described as obligate intracellular symbionts of gut flagellates in lower termites. However, 16S rRNA gene sequences of Endomicrobia have been detected also in the gut of insects that do not possess such flagellates, e.g. higher termites and cockroaches. When we eliminated the large gut flagellates of Reticulitermes santonensis by feeding a starch diet, we discovered novel lineages of Endomicrobia that were hitherto undetected in normally faunated specimens. The new phylotypes are clearly separated from the endosymbionts of gut flagellates and fall into the radiation of those from flagellate-free insects. Comprehensive phylogenetic analysis documented that Endomicrobia comprise an apical cluster of endosymbionts that is not necessarily monophyletic and several apparently basal lineages that include bacteria present in the gut of defaunated lower termites, the naturally flagellate-free guts of higher termites and scarab beetle larvae, and in the cow rumen. We propose that these lineages represent hitherto undetected free-living Endomicrobia that share a common ancestor with the intracellular symbionts.

In animals, the population genomic literature is dominated by two taxa, namely mammals and drosophilids, in which fully sequenced, well-annotated genomes have been available for years. Data from other metazoan phyla are scarce, probably because the vast majority of living species still lack a closely related reference genome. Here we achieve de novo, reference-free population genomic analysis from wild samples in five non-model animal species, based on next-generation sequencing transcriptome data. We introduce a pipe-line for cDNA assembly, read mapping, SNP/genotype calling, and data cleaning, with specific focus on the issue of hidden paralogy detection. In two species for which a reference genome is available, similar results were obtained whether the reference was used or not, demonstrating the robustness of our de novo inferences. The population genomic profile of a hare, a turtle, an oyster, a tunicate, and a termite were found to be intermediate between those of human and Drosophila, indicating that the discordant genomic diversity patterns that have been reported between these two species do not reflect a generalized vertebrate versus invertebrate gap. The genomic average diversity was generally higher in invertebrates than in vertebrates (with the notable exception of termite), in agreement with the notion that population size tends to be larger in the former than in the latter. The non-synonymous to synonymous ratio, however, did not differ significantly between vertebrates and invertebrates, even though it was negatively correlated with genetic diversity within each of the two groups. This study opens promising perspective regarding genome-wide population analyses of non-model organisms and the influence of population size on non-synonymous versus synonymous diversity., Author Summary The analysis of genomic variation between individuals of a given species has so far been restricted to a small number of model organisms, such as human and fruitfly, for which a fully sequenced, well-annotated reference genome was available. Here we show that, thanks to next-generation high-throughput sequencing technologies and appropriate genotype-calling methods, de novo population genomic analysis is possible in absence of a reference genome. We characterize the genomic level of neutral and selected polymorphism in five non-model animal species, two vertebrates and three invertebrates, paying particular attention to the treatment of multi-copy genes. The analyses demonstrate the influence of population size on genetic diversity in animals, the two vertebrates (hare, turtle) and the social insect (termite) being less polymorphic than the two marine invertebrates (oyster, tunicate) in our sample. Interestingly, genomic indicators of the efficiency of natural selection, both purifying and adaptive, did not vary in a simple, predictable way across organisms. These results prove the value of a diversified sampling of species when it comes to understand the determinants of genome evolutionary dynamics.

Termite gut flagellates are colonized by host-specific lineages of ectosymbiotic and endosymbiotic bacteria. Previous studies have shown that flagellates of the genus Trichonympha may harbour more than one type of symbiont. Using a comprehensive approach that combined cloning of SSU rRNA genes with fluorescence in situ hybridization and electron microscopy, we investigated the phylogeny and subcellular locations of the symbionts in a variety of Trichonympha species from different termites. The flagellates in Trichonympha Cluster I were the only species associated with 'Endomicrobia', which were located in the posterior part of the cell, confirming previous results. Trichonympha species of Cluster II from the termite genus Incisitermes (family Kalotermitidae) lacked 'Endomicrobia' and were associated with endosymbiotic Actinobacteria, which is highly unusual. The endosymbionts, for which we suggest the name 'Candidatus Ancillula trichonymphae', represent a novel, deep-branching lineage in the Micrococcineae that consists exclusively of clones from termite guts. They preferentially colonized the anterior part of the flagellate host and were highly abundant in all species of Trichonympha Cluster II except Trichonympha globulosa. Here, they were outnumbered by a Desulfovibrio species associated with the cytoplasmic lamellae at the anterior cell pole. Such symbionts are present in both Trichonympha clusters, but not in all species. Unlike the intracellular location reported for the Desulfovibrio symbionts of Trichonympha agilis (Cluster I), the Desulfovibrio symbionts of T. globulosa (Cluster II) were situated in deep invaginations of the plasma membrane that were clearly connected to the exterior of the host cell.

The effect of salinity was studied in natural populations of the black-chinned tilapia (Sarotherodon melanotheron) from West Africa. This euryhaline species colonizes nearly all coastal environments from bays to lagoons characterized by salinities ranging from fresh water to hypersaline water over 100 aEuro degrees. Individuals were sampled during the dry season at several locations characterized by different levels of salinity (3-102 aEuro degrees). Their osmotic status and their gills were analyzed. The branchial mitochondria-rich cells (MRC), localized at the basis of the filaments and along the lamellae in fish taken from the saline stations, showed a wide plasticity with significant differences in their number and size. The most striking results were a significant larger area (a parts per thousand 3x) and a higher number (a parts per thousand 55x) of MRC at high salinity (102 aEuro degrees) compared to low salinity (3 aEuro degrees). The major ion transporters and channels were localized by immunocytochemistry and different expression patterns have been recorded between stations. Despite an increased Na+/K+-ATPase (NKA) alpha-subunit expression and NKA activity, pointing to an increased monovalent ion excretion, a severe osmotic imbalance was recorded in animals living in hypersaline environments.

Many genetic changes that ultimately lead to adaptive evolution come with a short-term cost expressed in terms of reduced survival and reproduction. In the absence of genetic drift, it is unclear how such costly mutations may persist. Here we experimentally demonstrate that parasites can promote the persistence of costly genetic variants. We employed a genetically engineered strain (GMMO) of the bacterium Pseudomonas fluorescens as a model of the acquisition of a new gene either through a major mutation or through horizontal transfer, and examined its persistence in different evolving communities comprising an ancestral strain and a lytic bacteriophage. Whereas competition resulted in the elimination of the GMMO, inclusion of the phage promoted GMMO persistence. We provide evidence for why this effect is due to the differential susceptibility of GMMO and ancestral bacteria to phage.