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Nature-based Solutions (NbS) in urban areas can be solutions that simultaneously enable adaptation to climate change, preserve biodiversity, and ensure human health and well-being. Since NbS are open systems, their behavior is highly dependent on their interactions with the environment, which are particularly complex and diverse in the urban ecosystem. The dynamics of the urban socio-ecosystem are driven by humans who create new flows, new interactions and further redefine natural ecological processes. Urban NbS have the potential to deliver multiple benefits, such as cooling air, regulating the water cycle, capturing pollutants, producing biomass, contributing to the creation of ecological corridors, providing spaces for socialization and recreational activities, and improving quality of life. However, in the literature, their effectiveness is mainly assessed through siloed approaches, making it fragmented and unnuanced, with the outcomes rarely studied together. Following this, we develop a systemic framework, based on the “One Health” approach, to assess NbS as complex systems having interactions with biodiversity, microclimate, and humans. A well-performing NbS is assumed to be a solution in which biodiversity and humans are healthy in a mitigated microclimate. Through this systemic analysis, several outcomes of a NbS are studied together and links can be identified between the underlying processes, as synergies or antagonisms.This work presents the One Health assessment framework. It is based on semantic work to define the system and conceptualize the One Health approach. It was supplemented by a literature review of studies developing other systemic frameworks and studies on the impacts of NbS. In addition, the framework was first developed for a particular type of urban NbS, green spaces, in order to focus on solutions based on the same objects – lawn, shrub, and tree –, and therefore, with mostly identical ecological functions.This work was supported by the LabEx IMU (ANR-10-LABX-0088) of Université de Lyon, within the «Plan France 2030» operated by the French National Research Agency (ANR), and the French Agency for Ecological Transition (ADEME).

Aim Cities are thought to promote biological invasions because invasive species are more often introduced in urban areas and because they are more successful in disturbed environments. However, the association is not as strongly supported by the literature as is generally assumed and might depend on how urbanization and invasion are measured. In this study, we test if the type of data used to assess the link between urbanization and invasion can affect a study's conclusions. Location Europe and middle Rhône valley (~5000 km2 in south-eastern France). Method We studied the spatial distribution of the invasive garden ant Lasius neglectus in its current introduced range in Europe and tested its association with urbanization using three measures of invasion (presence-only, presence–absence and population area) and two measures of urbanization (urban/nonurban land cover classification and proportion of impervious surfaces (buildings, road) per spatial unit). Results Based on presence-only data across Europe, L. neglectus occurred in urban areas 10 times more often than expected from a random geographical distribution. However, when controlling for spatial bias in sampling effort with presence–absence data (1870 sampling locations in the middle Rhône valley, France), the occurrence of the species was independent of urbanization. Moreover, the surface occupied by L. neglectus populations was negatively correlated with urbanization. Main conclusions These findings show that the type of occurrence data used to test the link between urbanization and invasion can strongly affect the conclusion of a study. This is particularly concerning because invasion studies often use presence-only data that are likely biased towards cities. Future urban invasions studies must be carefully designed to avoid this pitfall.

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Species and nestmate recognition in social insects occurs mostly through cuticular hydrocarbons acting as chemical cues. These compounds generate a colony-specific odor profile depending on genetic and environmental factors. Species and nestmate recognition results in specific behavioral responses, regulating the level of aggression toward other individuals during an interaction. Although species discrimination and recognition cues have been poorly studied in the context of interspecific hybridization, such systems offer an opportunity to further investigate the influence of heritable and environmental factors on recognition. We explored the strength of discrimination in a hybrid zone between two ant species-Tetramorium immigrans and T. caespitum-by comparing cuticular hydrocarbon profiles and measuring intra- and interspecific worker aggression in both areas of sympatry and areas of allopatry among species. Species cuticular hydrocarbon profiles were well-differentiated and interspecific aggression was high, revealing highly discriminating species recognition cues. Hybrids' cuticular hydrocarbon profiles consisted of a mixture of the parental bouquets, but also exhibited hybrid-specific patterns. Behavioral assays showed that T. immigrans is as aggressive toward hybrids as toward heterospecifics. Finally, aggression between heterospecific workers was lower when interacting individuals came from areas of sympatry among species than from areas of allopatry. Taken as a whole, these findings paint a particularly complex picture of the recognition system in T. immigrans, T. caespitum, and their hybrids, and highlight that hybrid zones afford a still underexplored opportunity for investigating recognition mechanisms and discrimination between species.

Environmental niche models predict the presence of the invasive Argentine ant in north-western Europe, especially along all the French Atlantic coast. Yet, the species has never been observed North from the 45th parallel in Europe, suggesting either that current models are wrong or that Argentine ants are already spreading north inconspicuously. Here, we report a three-hectare wide colony of Argentine ants, detected in 2016 in Nantes, France, which is 300 km north of the former northern-most outdoor population of this species in Europe. COI sequencing revealed that the haplotype of this new colony is the same as the one found in the so-called Catalonian supercolony, which is distinct from the haplotype found over most of the species range in Europe. Our discovery confirms models’ predictions that Argentine ants can colonize north-western Europe and suggests that they might have already reached several other locations along the French Atlantic coast. Detection surveys should be conducted in order to assess Argentine ants’ invasion patterns in Western France, particularly in high introduction risk areas such as major cities and maritime ports.

Global changes, such as climate and urbanization, are strongly entwined and aggravated by the development of human activities, which also intensifies the human-mediated dispersal of species. However, few studies have explicitly considered the combined influence of urbanization and climate on species expansion. We investigated the combined roles of climate, urbanization and human-mediated dispersal in the expansion of Tetramorium immigrans (an invasive pavement ant in North America) in urban areas of South-eastern France. A total of 544 T. immigrans individuals were sampled from 16 urban gradients and genotyped at 14 microsatellite markers. Based on molecular ecology methods and statistical modelling, we evaluated the impact of climate and urbanization on its distribution patterns. Through the combined study of the occurrence probabilities of T. immigrans, its genetic structure and the founder effects within its populations, the effect of climate–urbanization interaction on species distribution was clearly evidenced, suggesting that in the north of its range, T. immigrans subsists under harsher climate by colonizing the most urbanized areas. Many taxa may conform to such pattern, making the combined study of climate and urbanization a necessary challenge for future studies. Distribution patterns concurred with similar observations in the American invasive range of T. immigrans, making it likely that it may not be native to the northernmost part of its European range. Cryptic invasions or discreet range shifts in response to increasing urbanization are likely to occur in many taxa, especially in ants, and deserve increased attention from researchers and managers alike.

Urban alteration of neutral and adaptive evolutionary processes is still underexplored. Using a genome-wide SNP dataset, we investigated (i) urban-induced modifications of population demography, genetic diversity and population structure and (ii) signature of divergent selection between urban and forest populations in the ant species, Temnothorax nylanderi. Our results did not reveal an impact of urbanization on neutral processes since we observed: (i) analogous genetic diversity among paired urban/forest sites and two control populations; (ii) weak population genetic structure explained neither by habitat (urban versus forest) nor by geography; (iii) a remarkably similar demographic history across populations with an ancestral growth followed by a recent decline, regardless of their current habitat or geographical location. The micro-geographical home range of ants may explain their resilience to urbanization. Finally, we detected 19 candidate loci discriminating urban/forest populations and associated with core cellular components, molecular function or biological process. Two of these loci were associated with a gene ontology term that was previously found to belong to a module of co-expressed genes related to caste phenotype. These results call for transcriptomics analyses to identify genes associated with ant social traits and to infer their potential role in urban adaptation.

International audience; 1. The hyporheic zone of rivers potentially acts as a dispersal corridor for ground-water organisms because it provides a spatially continuous interstitial habitat between isolated aquifers. Yet, the degree to which it can facilitate the move- ment of organisms has been hypothesized to vary in response to change in sedi- ment regime, which determines channel morphology.2. In this study, we used microsatellite markers to test for a relationship between the genetic structure and diversity of the minute interstitial isopod Proasellus walteri and channel morphology along three nearby hyporheic corridors differing widely in their sediment regime. We predicted that genetic diversity would decrease and genetic structuring would increase as sediment supply-limited channels would become prominent features in the river corridor. The reason is that such channels have fewer and less suitable sedimentary habitats for migra- tion because they lack large depositional bedforms such as gravel bars.3. Using genotypic data from seven microsatellite loci for a total of 713 individuals distributed among 25 demes, we found that demes had on average more alleles and were less differentiated in the river showing the most extensive alluvial depos- its and shortest length of sediment supply-limited channels. Population clusters were also of greater size, reaching up to 30 km in length. The longitudinal pattern of genetic differentiation in this sediment-rich river was best explained by hydro- logic distance and the longitudinal pattern of allelic richness was bell-shaped, as expected under a stepping-stone model with symmetrical migration.4. The length of sediment supply-channels was more important than hydrologic dis- tance in explaining the longitudinal distribution of genetic differentiation in the two other corridors facing a sediment shortage. Allelic richness decreased mono- tonically upstream in the most sediment-poor river. This correlates with the expan- sion further downstream of sediment supply-limited channels in this river, which is likely to decrease animal movement and hence gene flow among demes.5. Thisstudyprovidesthefirstevidencethatthedegreetowhichthehyporheiczone facilitates the movement of groundwater organisms varies greatly among rivers of contrasted geomorphology. Extending the application of riverscape genetics across a range of interstitial taxa and geomorphic settings holds much promise for assessing the contribution of the hyporheic zone to the dispersal of groundwater organisms.

Urbanization is a global change which deeply impacts landscapes. Long studied through transects along urbanization gradients, ecological response to urbanization can now be investigated precisely using direct GIS-based measures. Ecological responses are strongly scale-dependent as both large- and fine-scale environments drive species distributions. To bridge the gaps regarding the effect of multiple scales on the distribution of biodiversity in the context of urbanization, the present study questions how urbanization structures the distribution of Tetramorium ants at different spatial scales. Based on model averaging procedures, we investigated ~ 1400 individuals belonging to four Tetramorium species at four distinct spatial scales, from urban microhabitat (1 m around the nest) to urban landscape (500 m around the nest) in 19 urban gradients in South-eastern France. The probabilities of occurrences of Tetramorium caespitum and T. immigrans simultaneously depended on urbanization at the landscape and local scales, with T. caespitum avoiding urban microhabitats and impervious landscapes whereas T. immigrans favored them. These multi-scale impacts of urbanization were species-dependent as T. moravicum was associated with nonurban landscapes only, and T. semilaeve showed no association whatever the tested variables. These results highlight the importance of considering several spatial scales simultaneously to study the impact of urbanization on species distributions. The highly contrasted responses to urbanization of T. immigrans and T. caespitum may indicate niche partitioning processes driven by urbanization. The future monitoring of the distribution range dynamics of these two species should provide insightful information into the impact of urbanized landscapes on species distribution.

International audience; Limestone areas across the world develop karstic caves, which are populated by a wide range of macro‐ and microorganisms. Many of these caves display Paleolithic art or outstanding speleothems, and in the last century they have been subjected to anthropization due to touristic management and intense human frequentation. Despite their cultural importance and associated conservation issues, the impact of anthropization on cave biodiversity is not known. Here, we show that anthropization is associated with specific cave biota modifications. We compared diversity in four pristine caves, four anthropized show caves, and the iconic Lascaux Cave with even stronger anthropization. The predominant microbial higher taxa were the same in all caves, but the most anthropized cave (Lascaux) was unique as it differed from the eight others by a higher proportion of Bacteroidetes bacteria and the absence of Euryarchaeota and Woesearchaeota archaea. Anthropization resulted in lower diver‐sity and altered community structure for bacteria and archaea on cave walls, espe‐cially in Lascaux, but with a more limited effect on microeukaryotes and arthropods. Our findings fill a key gap in our understanding of the response of karstic communi‐ties to anthropization, by revealing that tourism‐related anthropization impacts on the prokaryotic microbiome rather than on eukaryotic residents, and that it shapes cave biota irrespective of cave natural features.

La puissance de calcul des nouvelles technologies de l'information, alliée à la multiplication et à la facilité d'accès des données spatialisées, offrent des opportunités croissantes en termes d’observation, d’interaction et d’analyse. Ainsi, utilisant des données spatiales capitalisées sur l’ensemble de l’agglomération lyonnaise, nous avons développé un nouveau service hébergé sur le site internet : webarmature.fr. Cette plateforme logicielle publique permet de visualiser, comparer et quantifier les dynamiques liées à l'occupation du sol sur le territoire du Grand Lyon. L'ensemble des données présentées sur le site ont été collectées dans le cadre du projet de recherche ARMATURE (LabEx Intelligences des Mondes Urbains (IMU), Université de Lyon (UDL)). Cette plateforme est conçue pour être dynamique et facilement adaptable à l’ensemble du territoire français. The rise of information technology offers new possibilities in terms of observation, interaction and analysis of spatial data. Using public spatial data on the Grand Lyon metropolitan area, we have developed a new service based on the web site webarmature.fr. This platform makes it possible to visualize, compare and quantify landcover dynamics in the Grand Lyon territory. All the data presented on the site are public or have been generated by the ARMATURE research project (LabEx Intelligences des Mondes Urbains (IMU), Université de Lyon (UDL)). This platform was designed to be reproduced or adapted for other French territories.

International audience

International audience; 1. In the context of climate changes, factors that determine the distri- bution patterns of European species of the ubiquitous ant genus Tetramorium were investigated.2. The study took place along a steep North-South climatic gradient across the boundary between the European Continental and Mediterranean biogeo- graphical regions spanning 460 km along the Rho^ne valley, France.3. Ants from 1690 Tetramorium colonies were collected in 19 sampling zones. Species were identified using an integrative approach based on a two-step pro- cess combining nuclear DNA (14 microsatellite markers), morphological exami- nation and mitochondrial DNA cytochrome oxidase I sequencing. The impact of climate on species distribution patterns was tested using bioclimatic vari- ables.4. Species discrimination was successful, despite a complex situation with cryptic species, inter-specific hybridisation and uneven sampling across species. Our results showed a strong effect of latitude, temperature and rainfall on the distribution of three of four species. Tetramorium semilaeve was found only south of the boundary, in warmer and dryer sites; Tetramorium caespitum extended north and 70 km south of the boundary and favoured colder sites with strong seasonal variation. Tetramorium immigrans was absent from the northernmost sampling zones and favoured warmer and wetter sites. Tetramor- ium moravicum was mostly found close to the boundary, but without significant climatic preferences.5. The fundamental role of climate as a factor limiting the ranges of these species at a major biogeographical boundary is confirmed. Monitoring range limits of these strongly climate-dependant species may offer exciting insights on the impact of climate changes on species distributions.

International audience; Understanding the distribution of parasites is crucial for biodiversity conservation. Here, we studied the distribution of the ectoparasitic fungus Laboulbenia formicarum in native and invasive Lasius ants in a 2000 km2 area. We screened over 16,000 ant workers in 478 colonies of five different species. We found that Lab. formicarum was rare in native Lasius species but infected 58% of the colonies of the invasive species Las. neglectus. At landscape scale, Lab. formicarum presence could not be explained by geographic and genetic distances between Las. neglectus colonies but was associated with hotter and dryer climatic conditions and its prevalence in colonies increased with urbanization. Within infected colonies, fungal prevalence varied from 0 to 100 percent within meters and was negatively correlated with impervious ground cover. In a changing world, our findings emphasize the importance of land-use and climatic factors in shaping the distribution and prevalence of fungal parasites.

International audience; Urbanization is a major global change inducing complex and multiple modifications of landscapes and eco- systems. The spatial distributions of organisms experiencing these modifications will likely shift specifically, depending on each species’ response to each environmental modification induced by urbanization. We sampled two ant genera (Lasius and Tetramorium) at 1248 locations along an urbani- zation gradient in Lyon, France and used high resolution spa- tial layers for 18 spatial (e.g., open habitat fragmentation, bio- climatic data and surface temperatures) and temporal (e.g., comparison of Normalized Difference Vegetation Index be- tween 1986 and 2015) environmental variables associated with urbanization. Coupling two different analytical methods (Outlying Mean Index and Boosted Regression Trees), we showed that each species’ distribution was influenced by its own combination of environmental factors. Two morphologically cryptic Tetramorium species (T. sp.E and T. sp.U2) were both highly abundant but with opposite responses to urbanization: while T. sp.E was favored by urbanized habitat, T. sp.U2 avoided urbanized areas. Among Lasius species, we detected 63 occurrences of the invasive ant Lasius neglectus, the distribution of which was favored only by embankments along roads. We found that, even at this reduced spatial scale, climatic effects influenced most species and interacted with urbanization factors.

International audience; Urban green spaces are vital parts of any city due to their capacity to provide a large number of urban services to a wide range of stakeholders. However, since urban green spaces can consume large areas of the city, where land is both scarce and expensive, planners and managers are usually faced with conflicting challenges. They must endeavour to provide the tremendous amount of urban services, which are expected by the stakeholder, while simultaneously, attempting the careful design of urban green spaces in a limited area. Using a combined method based on the findings of a literature review, stakeholder participation and a case study, this paper puts forward a new typology, that of improving multi-functionality of the urban green space, as a solution to the challenge of limited area available. This new typology suggests that the linking of greenspace components with urban green services could allow planners and managers to overlay the services expected, by selecting the best possible combination of greenspace components. In fact, with this new typology, planners and managers could choose the combination of greenspace components first, and then establish the set of urban services provided. It was tested on the urban green spaces of the Doua campus (Lyon, France) which led to suggestions, made to the campus manager, on how to improve urban services without increasing the green areas.

Urbanized landscapes are the theater of multiple simultaneous biological invasions likely to affect spread dynamics when co-occurring introduced species interact with each other. Interactions between widespread invaders call for particular attention because they are likely to be common and because non-additive outcomes of such associations might induce negative consequences (e.g., enhanced population growth increasing impacts or resistance to control). We explored the invasions of two widespread invasive taxa: the Japanese knotweed species complex Fallopia spp. and the invasive garden ant Lasius neglectus, in the urban area of Lyon (France). First, we investigated landscape habitat preferences as well as co-occurrence rates of the two species. We showed that Fallopia spp. and L. neglectus had broadly overlapping environmental preferences (measured by seven landscape variables), but their landscape co-occurrence pattern was random, indicating independent spread and non-obligatory association. Second, as Fallopia spp. produce extra-floral nectar, we estimated the amount of nectar L. neglectus used under field conditions without ant competitors. We estimated that L. neglectus collected 150–321 kg of nectar in the month of April (when nectar production is peaking) in a 1162 m2 knotweed patch, an amount likely to boost ant population growth. Finally, at six patches of Fallopia spp. surveyed, herbivory levels were low (1–6% loss of leaf surface area) but no relationship between ant abundance (native and invasive) and loss of leaf surface was found. Co-occurrences of Fallopia spp. and L. neglectus are likely to become more common as both taxa colonize landscapes, which could favor the spread and invasion success of the invasive ant.

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When deciding to mate, it is assumed that females choose males bearing genes that will improve the genetic quality of their offspring, which is affected by both additive and nonadditive genetic variation. In this context, a ‘compatible genes’ model has been put forward to explain female mating decisions. According to this model, females are assumed to increase the genetic quality of their offspring by choosing mates on the basis of interactions between maternal and paternal genomes. Yet, this model is mainly supported by empirical data in endotherm vertebrates. Few studies have investigated this issue in terrestrial ectotherms like amphibians. These organisms often live in spatially structured populations characterized by small subpopulations and a high degree of philopatry, leading to striking reduction in gene flow, high genetic drift and relatively high inbreeding levels. In such a situation, one might expect that natural selection should favour mating tactics limiting the risk of inbreeding depression. In this paper, using an experimental approach controlling for the reproductive state of males, we examined how genetic compatibility may affect mating behaviour in an anuran, the yellow-bellied toad, Bombina variegata. First, our analyses confirmed a high degree of inbreeding in the studied population. Yet, we did not find any mating tactic that reduced the risk of inbreeding depression. Contrary to our expectations, males more closely related to the female had the higher mating success. We discuss the ecological and evolutionary implications of these results.

International audience; Roads are of major concern in conservation biology, as they are known to restrict animal movements through landscape fragmentation, and may therefore impact genetic patterns in native terrestrial organisms. We assessed the effect of two large-scale transportation infrastructures (LTIs), a 40-year-old highway and a 30 year-old high-speed railway, on the spatial genetic structure of the alpine newt Ichthyosaura alpestris, a highly nomadic amphibian. Genetic data were gathered following a targeted individual-based sampling scheme and analysed using both overlay and correlative methods. While simulations suggested that the highway may be old enough for a significant barrier effect to be detected, LTIs were never detected as barriers to gene flow: inferred genetic boundaries rather coincided with transition zones between major landscape entities. Furthermore, spatial principal component analysis, a method designed to reveal cryptic genetic spatial patterns in high gene flow species, counter-intuitively suggested that the highway may act as a potential dispersal corridor in low-quality habitats, thus challenging traditional hypotheses on road impacts in amphibians. Our study showed that considering local interactions between species, infrastructures and landscape-specific characteristics is essential for better understanding the potential impacts of roads on movement patterns in terrestrial organisms.

Genetic influences on polyethism within social insect colonies are well known, suggesting that the determination of caste (soldiers and minor workers) may also be genetically mediated. The Australian sugar ant Camponotus consobrinus is suitable for such a study, having soldiers and minor workers that follow a complex allometry. Further, although most C. consobrinus colonies are monogynous, 13 of 42 surveyed using microsatellites were found to be polygynous. Thus, although a minority of colonies were polygynous, the great majority of queens live in polygynous colonies. From the 29 monogynous colonies studied, we inferred that the queens are monandrous. Ants from four polygynous colonies were assigned to families on the basis of microsatellite genotypes, after measurements had been taken of head width and scape length. These measurements reflect a complex allometry interpretable as soldier and minor worker growth curves with a large changeover zone. Genetic influence on caste determination was examined by testing for differences between families within colonies in the distribution of scape lengths, residuals from the overall colony allometric curve, and proportions of soldiers and minor workers (as determined by head width falling above or below the inflection point of the overall colony allometric curve). Families in all four colonies differed significantly in caste proportions and in head-width distributions, and three of the four colonies showed significant differences between families in residuals from the overall colony growth curve. Nested ANOVAs using head widths and scape-length residuals showed that when the effect of family is removed, intercolony differences in allometry are negligible. This evidence indicates genetic rather than environmental causes for the observed differences between families. We speculate that this variation may reflect some selective advantage to within-colony heterogeneity between families or that selective differences are few between a wide array of family growth patterns.

International audience; Genetic data are increasingly used in landscape ecology for the indirect assessment of functional connectivity, that is, the permeability of landscape to movements of organ- isms. Among available tools, matrix correlation analyses (e.g. Mantel tests or mixed models) are commonly used to test for the relationship between pairwise genetic dis- tances and movement costs incurred by dispersing individuals. When organisms are spatially clustered, a population-based sampling scheme (PSS) is usually performed, so that a large number of genotypes can be used to compute pairwise genetic distances on the basis of allelic frequencies. Because of financial constraints, this kind of sam- pling scheme implies a drastic reduction in the number of sampled aggregates, thereby reducing sampling coverage at the landscape level. We used matrix correlation analy- ses on simulated and empirical genetic data sets to investigate the efficiency of an individual-based sampling scheme (ISS) in detecting isolation-by-distance and isola- tion-by-barrier patterns. Provided that pseudo-replication issues are taken into account (e.g. through restricted permutations in Mantel tests), we showed that the use of inter- individual measures of genotypic dissimilarity may efficiently replace interpopulation measures of genetic differentiation: the sampling of only three or four individuals per aggregate may be sufficient to efficiently detect specific genetic patterns in most situa- tions. The ISS proved to be a promising methodological alternative to the more con- ventional PSS, offering much flexibility in the spatial design of sampling schemes and ensuring an optimal representativeness of landscape heterogeneity in data, with few aggregates left unsampled. Each strategy offering specific advantages, a combined use of both sampling schemes is discussed.

International audience; Mate preference was long assumed to be static and open-ended. However, a growing body of evidence actually suggests that the predominant factor in mate choice fluctuates due to the context dependence of the factors involved in sexual selection. In particu- lar, fluctuation in the local environment, the density of individuals, and the presence of heterospecifics can all alter the strength, form, or direction of sexual selection by shaping the fitness costs and benefits of the traits that mediate male–female interactions. Amphibians constitute useful biological models to examine context dependence in sexual selection as the availability of suitable breeding resources may significantly impact the cost–benefit trade-off between mating strategies. Using an experimental approach, we examined how the risk of larval competition in breeding ponds affects pond occupancy, male–male spacing behavior, and spawn- ing decisions in an anuran, the yellow-bellied toad (Bombina variegata). Then, we examined how female mate choice is affected by male body condition and how the risk of larval competition might influence females when choosing a mate. Our results indicate that male pond preference is strongly affected by the presence of conspecific tadpoles. Males preferentially selected ponds free of tadpoles, and spawning mainly occurred in these same ponds. This preference influenced male spacing behavior by enhancing the proximity of competing males when the availability of good-quality sites was experimentally manipulated, which had further significant consequences on females’ choice of mate. The article also discusses the evolutionary causes and consequences of such context- dependent mate choice in amphibians and beyond.

International audience; This study introduces a novel DNA sampling method in amphibians using skin swabs. We assessed the relevancy of skin swabs relevancy for genetic studies by amplifying a set of 17 microsatellite markers in the alpine newt Ichthyosaura alpestris, including 14 new polymorphic loci, and a set of 11 microsatellite markers in Hyla arborea, from DNA collected with buccal swabs (the standard swab method), dorsal skin swabs and ventral skin swabs. We tested for quality and quantity of collected DNA with each method by comparing electrophoresis migration patterns. The consistency between genotypes obtained from skin swabs and buccal swabs was assessed. Dorsal swabs performed better than ventral swabs in both species, possibly due to differences in skin structure. Skin swabbing proved to be a useful alternative to buccal swabbing for small or vulnerable animals: by drastically limiting handling, this method may improve the trade-off between the scientific value of collected data, individual welfare and species conservation. In addition, the 14 new polymorphic microsatellites for the alpine newt will increase the power of genetic studies in this species. In four populations from France (n = 19-25), the number of alleles per locus varied from 2 to 16 and expected heterozygosities ranged from 0.04 to 0.91. Presence of null alleles was detected in two markers and two pairs displayed gametic disequilibrium. No locus appeared to be sex-linked.

International audience; Introduced species are confronted with new environments to which they need to adapt. However, the ecological success of an introduced species is generally difficult to predict, especially when hybridizations may be involved in the invasion success. In western Europe, the lake frog Pelophylax ridibundus appears to be particularly successful. A reason for this species' success might be the presence of the invader's genetic material prior to the introduction in the form of a hybrid between P. ridibundus and a second indigenous water frog species. These hybrids reproduce by hybridogenesis, only transmitting the ridibundus genome to gametes and backcrossing with the indigenous species (i.e. P. lessonae). This reproductive system allows the hybrid to be independent from P. ridibundus, and allows the ridibundus genome to be more widely spread than the species itself. Matings among hybrids produce newly formed P. ridibundus offspring (N), if the genomes are compatible. Therefore, we hypothesize that hybridogenesis increases the invasiveness of P. ridibundus (1) by enhancing propagule pressure through N individuals, and/or (2) by increasing adaptation of invaders to the native water frogs' habitat through hybrid-derived ridibundus genomes that are locally adapted. We find support for the first hypothesis because a notable fraction of N tadpoles is viable. However, in our semi-natural experiments they did not outperform ridibundus tadpoles in the native water frogs' habitat, nor did they differ physiologically. This does not support the second hypothesis and highlights ecological constraints on the invasion. However, we cannot rule out that these constraints may fall with ongoing selection, making a replacement of indigenous species highly probable in the future.

Worker and queen samples of the Argentine antIridomyrmex humilis were analysed using allozyme electrophoresis. Two loci,peptidase andglucosephosphate isomerase, were found to be stainable and polymorphic. Both revealed an estimated relatedness in nestmate females that was close to zero, which is a consequence of the strong polygyny in this species. The inbreeding coefficient was found to be close to zero, which can be explained, in spite of intra-nest mating taking place inI. humilis, by the high mobility of mated queens.

International audience; Seventeen novel microsatellite markers were characterized from an enriched DNA library for the invasive carabid beetle Merizodus soledadinus. Loci were tested, as parts of two multiplex sets in 48 M. soledadinus from 2 populations. 14 loci gave reliable amplification, and genetic diversity ranged from 2 to 6 alleles per locus. In other species of the supertribe trechitae, 8 loci reliably amplified in Eotachys bistriatus, whereas all failed for Trechisibus antarcticus and Trechus obtusus.

Five highly polymorphic (GA)n microsatellite loci are reported for the formicine ant Camponotus consobrinus. The occurrence of many nests with a simple family structure enabled a search for new mutations, 11 of which were found from 3055 informative typings. These mutations were not randomly distributed across loci, 10 of them occurring at the locus Ccon70. The spectrum of mutations across alleles at Ccon70 was also nonrandom, with all of them occurring in alleles in the upper half of the allele size distribution. Six of the Ccon70 mutations decreased allele size. The mutations observed fit the stepwise mutation model well, i.e. mutations could always be assigned to an allele which differed in size from them by one repeat unit. The parental origins of the Ccon70 mutations were established and appear more female biased than vertebrate mutations, significantly so compared with human haemophilia A and primate intron mutations. This result may indicate that the lack of meiosis in males (which are haploid in ants) reduces the mutation rate in that sex relative to species in which both sexes are diploid.

Social insects present many phenomena seen in all organisms but in more extreme forms and with larger sample sizes than those observable in most natural populations of vertebrates. Microsatellites are proving very much more informative than allozymes for the analysis of population biological problems, and prolifically polymorphic markers are fairly readily developed. In addition, the male-haploid genetic system of many social insects facilitates genetic analysis. The ability to amplify DNA from sperm stored in a female's sperm storage device enables the determination of mating types long after the death of the short-lived males, in addition to information on the degree of mixing of sperm from different males. Mitochondrial (mt) DNA sequences are also proving important, not only in phylogenetic studies but also in molecular population genetics, as a tracer of female movements. Mitochondrial markers have definitively shown the movement of females between colonies, challenging models giving exclusive primacy to kin selection as the explanation for multiqueen colonies, in Australian meat ants, Iridomyrmex purpureus, and the aridzone queenless ant Rhytidoponera sp. 12. Microsatellite and mtDNA variation are being studied in Camponotus consobrinus sugar ants, showing an unexpected diversity of complexity in colony structure, and microsatellites have shown that transfer of ants between nests of the weaver ant Polyrhachis doddi must be slight, despite an apparent lack of hostility.

International audience; Effective population size (Ne) is one of the most important parameters in, ecology, evolutionary and conservation biology; however, few studies of Ne in surface freshwater organisms have been published to date. Even fewer studies have been carried out in groundwater organisms, although their evolution has long been considered to be particularly constrained by small Ne. In this study, we estimated the contemporary effective population size of the obligate groundwater isopod: Proasellus walteri (Chappuis, 1948). To this end, a genomic library was enriched for microsatellite motifs and sequenced using 454 GS-FLX technology. A total of 54,593 reads were assembled in 10,346 contigs or singlets, of which 245 contained candidate microsatellite sequences with suitable priming sites. Ninety-six loci were tested for amplification, polymorphism and multiplexing properties, of which seven were finally selected for Ne estimation. Linkage disequilibrium and approximate Bayesian computation methods revealed that Ne in this small interstitial groundwater isopod could reach large sizes (> 585 individuals). Our results suggest that environmental conditions in groundwater, while often referred to as extreme, are not necessarily associated with small Ne.

THE success of organisms and their increasing complexity throughout the course of evolution are thought to have depended on a small number of important transitions, one of which was the shift from a solitary lifestyle to societies of organisms exhibiting division of labour and having specialized castes1,2. The most familiar examples of the advantages arising from division of labour and caste differentiation come from social insects3. It has been suggested that the proportion of workers of various physical castes has evolved to enhance the fitness of colony members4,6 with the prediction that caste ratios should vary with environmental factors such as predation, competition and food availability. However, because it has been difficult to manipulate experimentally the environmental factors believed to influence optimal caste ratio, demonstration of adaptive caste distribution has remained elusive7–10. Here we show that colonies of the ant Pheidole pallidula increase the relative investment in soldier production after perceiving the presence of foreign con-specific colonies. This is the first experimental demonstration of a social insect altering physical caste ratios in an adaptive manner.

Climate change, urbanization, biological invasions and interspecific hybridization are major current threats to biodiversity. The objective of this thesis was to assess their interactive effects in Tetramorium ant species from the Rhône-Saône valley in France. Using a broad array of tools from several fields of biology, I worked on almost two thousand colonies from five Tetramorium species including T. immigrans and T. caespitum. Both climate and urbanization limited the ranges of these species, and urbanization impacted their distributions simultaneously at several spatial scales. The occurrence probabilities of T. immigrans depended on the interaction between climatic and urban factors. Several introductions from external sources seemed to have given rise to four genetically distinct populations of T. immigrans, making it likely that it is not native to the northernmost urban areas. Hybridization and introgression between T. immigrans and T. caespitum was frequent in zones of sympatry, and the detection of nuclear DNA backcrosses and mitochondrial-nuclear DNA discordance between the two species suggested that hybridization lead to fertile offspring (i.e. introgression). Cuticular hydrocarbon profiles were clearly differentiated between the two species and were correlated to heightened interspecific aggression against heterospecifics. Both species presented a monogyne polyandrous mating system, in which hybrid queens but no hybrid fathers contributed to hybrid offspring. Few studies on interspecific hybridization have addressed global change or biological invasions. These concepts are infrequently studied together, and their interactive effects are overlooked in the current literature. Taking these interrelationships into account and exploring multiple scales are essential to better understand the processes that generate patterns of genetic exchange, Changement climatique, urbanisation, invasions biologiques et hybridation interspécifique constituent des menaces majeures pour la biodiversité. L'objectif de cette thèse a été d'évaluer leurs effets interactifs sur les fourmis du genre Tetramorium de la vallée du Rhône, France. Près de 2000 colonies de 5 espèces de Tetramorium ont été étudiées. Les résultats démontrent que le climat et l'urbanisation limitent leurs aires de répartition et que l'urbanisation impacte leurs distributions simultanément à plusieurs échelles spatiales. Les probabilités d'occurrence de T. immigrans dépendent de l'interaction entre facteurs climatiques et urbains. Quatre populations génétiques de T. immigrans résultent de plusieurs introductions de sources externes, ce qui signifie que cette espèce n’est pas indigène dans les zones urbaines du nord. T. immigrans et T. caespitum produisent des hybrides dans les zones de sympatrie. La détection de rétrocroisements et de discordances entre ADN mitochondrial et nucléaire suggère que cette hybridation conduit à une descendance fertile, donc de l’introgression. Les profils d'hydrocarbures cuticulaires sont bien différenciés entre les deux espèces et sont corrélés à une agression forte contre les hétérospécifiques. Ces espèces présentent un système d'accouplement monogyne polyandre, dans lequel les reines hybrides mais pas les pères hybrides contribuent à la descendance hybride. Les études sur l'hybridation interspécifique n'ont qu'occasionnellement concerné les changements globaux ou invasions biologiques. Ces concepts eux-mêmes sont peu étudiés ensemble et leurs effets interactifs sont négligés dans la littérature actuelle. La prise en compte de ces interrelations et l'exploration de plusieurs échelles sont essentielles pour mieux comprendre les processus qui génèrent des modèles d'échange génétique

Urbanization is a complex process involving simultaneous changes in several environmental conditions, including ground and air temperature (urban heat island effect), habitat fragmentation and chemical pollution. These changes are often associated with biodiversity loss and changes in ecosystems functioning. However, more than a sink for biodiversity, urban areas constitute true ecosystems where many native and alien species survive and even grow stable populations. The “urban ecosystem” is now considered as an important element in the functioning of densely populated environments, in human health and well-being, as well as in biodiversity conservation. More fundamentally, urbanization constitutes “real life experiment” offering ecologists an opportunity to better understand ecological and evolutionary processes over fine spatial and temporal scale. This thesis investigates ecological and evolutionary consequences urbanization at different biological organization levels using ants (Formicidae) as biological models. First, at the biological community level, we showed that native and alien ant responses to urbanization were species-specific as each species was affected by its own set of environmental changes associated with urbanization (e.g., fragmentation, ground temperature) and climate. Second, we explored the little studied process of human-mediated dispersal by (i) proposing a novel theoretical framework focusing on human activities rather than directly on species and (ii) developing an innovative simulation model of dispersal by transport in terrestrial landscapes, MoRIS (Model of Routes of Invasive Spread). Third, we investigated how urbanization affected novel biotic interactions between an alien ant species (Lasius neglectus), an alien ectoparasite fungus (Laboulbenia formicarum) and native ant species. We showed that urbanization impacted the size of L. neglectus colonies, which were smaller in urban area, as well as L. formicarum prevalence on L. neglectus, which was higher in urban areas. Finally, we investigated intraspecific variations between urban and rural conspecifics of an urban tolerant species: Lasius niger. We found that urban young queens were smaller and lighter, less stressed by high temperature and performed multiple mating more often than rural young queens. In common garden, colony founding success were globally similar but urban incipient colonies produced significantly less pupae (and consequently workers). We also found that workers produced in common garden experiments were more variable in size (higher head width variance in both inter- and intra-colony) in urban colonies than in rural colonies. No evidence for genetic differentiation between urban and rural populations was found, suggesting that gene flow was not disrupted between urban and rural populations. All our results converge to a renewed vision of ecological and potential evolutionary dynamics occurring in urban environments. Further investigation will be necessary to assess how ecological processes influence evolutionary trajectories in urban ecosystems, using both ecological (e.g. ant densities and abundances along the urban gradient) and genomic approaches (e.g. using “genotyping by sequencing” methods to identify genes responsible for adaptation to urbanization), L'urbanisation est un processus complexe tant par les mécanismes historiques, sociaux, économiques et environnementaux qu'il implique que par les multiples modifications qu'il provoque au sein des écosystèmes. Ainsi, les paysages urbanisés sont soumis à des changements spatialement et temporellement abrupts des conditions environnementales comme la température au sol et dans l'air, la fragmentation des habitats et les concentrations de divers polluants. Pourtant, malgré leur apparente inhospitalité pour la biodiversité, les milieux urbanisés sont de véritables écosystèmes où de nombreuses espèces, natives et invasives, sont capables de survivre et même de prospérer. L‟ « écosystème urbain » est désormais considéré comme un élément important du fonctionnement des environnements densément peuplés, de la santé et du bien être humain ainsi que de la conservation de la biodiversité. De manière plus fondamentale, l'urbanisation, au même titre que le changement climatique et les processus d'invasions biologiques, est une « expérience grandeur nature » nous offrant l'opportunité de comprendre les règles d'assemblage des communautés biologiques, les processus de sélection d'habitat et de dispersion ou encore les processus évolutifs d'adaptation et de diversification. Ce travail s'inscrit dans ce cadre de pensée en se proposant d'étudier les conséquences écologiques et évolutives de l'urbanisation à différents niveaux d'organisations biologiques chez les Formicidae. Cette thèse comprend 4 chapitres s'organisant autour des thèmes et questions suivants : Chapitre 1 : Urbanisation et communautés biologiques : Comment l'urbanisation affecte-t-elle la distribution des espèces à l'échelle du paysage ? Chapitre 2 : Urbanisation et dispersion par l'être humain : Conceptualisation et modélisation du rôle des activités humaines et des réseaux de transports dans la dispersion d'espèces. Chapitre 3 : Urbanisation et interactions biotiques : L'urbanisation affecte-t-elle les patrons de co-invasions d'un couple invasif hôte-parasite introduits indépendamment ? Chapitre 4 : Urbanisation et variations intraspécifiques : Les populations urbaines et rurales présentent-elles des différences de traits biologiques ? Nos résultats démontrent qu'en tant que changement multifactoriel, l'urbanisation affecte de manière complexe la composition des communautés biologiques en modifiant de manière idiosyncrasique la distribution des espèces natives et invasives. En effet, chacune des 7 espèces de fourmis étudiées était affecté par une combinaison unique de facteur environnementaux associés à l'urbanisation (p.ex. fragmentation des milieux ouverts, température de surface) mais également au climat (Chapitre 1, Gippet et al. 2016 Urban Ecosystems). Parce qu'ils concentrent des activités humaines, les paysages urbanisés sont le théâtre de multiples invasions biologiques. En effet, l'être humain déplace de nombreuses espèces, leur permettant de franchir des barrières biogéographiques mais aussi de se propager au sein des paysages. Afin de provoquer la discussion autour du concept de la dispersion des espèces par l'Homme, nous proposons un nouveau point de vue général centré sur les activités humaines (Chapitre 2, Partie 1, Gippet et al. soumis) ainsi qu'un modèle de propagation secondaire d'espèce invasive par les activités humaines : MoRIS, dont la principale innovation est d'utiliser la structure du réseau de transport pour influencer la direction des événements de dispersion (Chapitre 2, Partie 2, Gippet et al. In prep). La suite est à retrouver sur la version téléchargeable du manuscrit

Braided rivers are large alluvial rivers found in piedmont mountainous areas. These rivers are very dynamic systems in space and time and exhibit particular geomorphology. The river flows alternatively into large alluvial plains or narrowing parts (also defined as canyons). This geomorphology impacts groundwater-surface water exchanges and sedimentary thickness. Groundwater-surface water exchanges occur at different scales, then interacting to shape biotic and abiotic filters for invertebrate communities. Canyons can reduce sedimentary continuity or interrupt it and may represent strong barriers to dispersal for sedimentary-dwelling organisms. This present work aimed at evaluating the effects of geomorphology in invertebrate community structure and as a potential barrier to dispersal in the subterranean organism Proasellus walteri. The different results obtained have shown that geomorphology structured invertebrate communities, highlighting a strong response in groundwater communities but not in surface communities and have shown that downstream parts of alluvial plains were hotspots of biodiversity. The results of this study also concluded on a positive effect of geomorphology in braided rivers on the genetic structure of P. walteri and underlined large effective population size and high dispersal ability, then removing some misconceptions about subterranean environment, Les rivières en tresses sont des grandes rivières alluviales de piémont montagneux à forte dynamique spatio-temporelle et à géomorphologie particulière. Leur cours traverse alternativement de vastes plaines et des rétrécissements de vallées ou canyons. Cette géomorphologie influence fortement les échanges d’eau entre la rivière avec sa nappe souterraine et sur l’épaisseur sédimentaire. Les échanges d’eau entre la rivière et sa nappe se produisent à différentes échelles allant de la vallée jusqu’à des bancs de graviers et peuvent créer des filtres biotiques et abiotiques qui influencent les communautés d’invertébrés. Les canyons créent des zones de moindre épaisseur sédimentaire voire d’absence de sédiments et peuvent représenter de fortes barrières à la dispersion pour des organismes inféodés au milieu sédimentaire souterrain. Ce travail de thèse a cherché à évaluer dans quelle mesure la géomorphologie pouvait donc structurer les communautés d’invertébrés de surface et souterraines et pouvait jouer sur la dispersion d’un organisme souterrain Proasellus walteri. Les différents résultats obtenus ont permis de montrer que la géomorphologie structurait les communautés d’invertébrés en mettant en évidence une forte réponse des communautés souterraines mais pas de surface et créait des zones de forte biodiversité à l’aval des plaines. Les résultats de cette étude ont également permis de conclure sur un effet positif de la géomorphologie des rivières en tresses sur la structuration génétique de P. walteri et de mettre en évidence de grandes tailles de populations ainsi que de fortes capacités de dispersion, permettant d’écarter certaines idées reçues sur le milieu souterrain

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