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Dispersal is a key process for the dynamics and functioning of meta-communities and meta-ecosystems. Meta-ecosystem theory, however, does not fully integrate the possible effects of dispersal, largely assuming random diffusion of organisms and nutrients, contrasting with rising empirical evidence for intraspecific variability in dispersal strategies. Dispersal is often associated with a suite of phenotypic traits, forming dispersal syndromes. Since phenotypic variability is now acknowledged as a key factor mediating ecosystem dynamics, we argue that dispersal syndromes can link trait-based ecology and meta-ecosystem functioning together. We highlight that the dispersal of individuals can be associated with functional effect traits and can therefore alter trophic and nutrient-mediated interactions in ecosystems. We illustrate how the association between dispersal tendency and functional traits can modify the spatial heterogeneity of ecosystems.

International audience; Phenotypic plasticity is increasingly recognized as a key element of eco-evolutionary dynamics, but it remains challenging to assess because of its multidimensional nature. Indeed, organisms live in complex environments where numerous factors can impact the phenotypic expression of traits (inter-environment axis), possess multiple traits that can influence each other's expression (inter-trait axis) and differ in their genetic background (inter-genotype axis), which can not only impact the traits' values but also their plasticity. We addressed six questions related to phenotypic plasticity: (a) do different environmental gradients show similar effects on a given trait? (b) Are the effects of two environmental gradients on a trait additive? (c) Do different traits show similar plastic response to a given environmental gradient? (d) Do the (co)variances between traits vary across environmental gradients? (e) Do genotypes differ in their plastic response to a given environmental gradient? (f) Are some genotypes more plastic than others across all traits? We designed a microcosm experiment using the protist Tetrahymena thermophila aimed at encompassing all these aspects of phenotypic plasticity. We exposed 15 distinct genotypes to 25 combinations of temperature and nutrient availability and assessed the plasticity of five phenotypic traits. Our results show strong differences in the plastic response depending on the environmental gradient, not only regarding the shape of the reaction norm of the different traits tested, but also in the overall plasticity of the organisms. We did not find any covariance between traits that was consistent across all environments. Overall, our results suggest independent impacts of the environmental dimension considered on the observed plastic response. These results underline potential difficulties in generalizing findings about plasticity to all environments and all traits.

Habitat fragmentation is expected to reduce dispersal movements among patches as a result of increased inter-patch distances. Furthermore, since habitat fragmentation is expected to raise the costs of moving among patches in the landscape, it should hamper the ability or tendency of organisms to perform informed dispersal decisions. Here, we used microcosms of the ciliate Tetrahymena thermophila to test experimentally whether habitat fragmentation, manipulated through the length of corridors connecting patches differing in temperature, affects habitat choice. We showed that a twofold increase of inter-patch distance can as expected hamper the ability of organisms to choose their habitat at immigration. Interestingly, it also increased their habitat choice at emigration, suggesting that organisms become choosier in their decision to either stay or leave their patch when obtaining information about neighbouring patches gets harder. This study points out that habitat fragmentation might affect not only dispersal rate but also the level of non-randomness of dispersal, with emigration and immigration decisions differently affected. These consequences of fragmentation might considerably modify ecological and evolutionary dynamics of populations facing environmental changes.

International audience; A functional definition of the habitat-concept based on ecological resources incorporates three interconnected parameters: composition, configuration, and availability of the resources. The intersection of those parameters represents the functional habitat of a given population or species. Resource composition refers to the co-occurrence of the resources required by each individual to complete its life cycle. Resource configuration refers both to the way individual resources are spatially distributed within the habitat and the way all the resources are organized in the habitat space. Resource availability refers to the accessibility and procureability of resources. Variation in these variables is predicted to influence the demography of the population. To test the suitability of this definition and its transferability across landscapes, we first conducted a very detailed study on habitat and resource use of five butterfly species within a large nature reserve. Second, we conducted a larger-scale study, focusing on metapopulations of two species. We monitored demography for each species and tested whether its variation can be explained by (1) the vegetation type, (2) the vegetation composition or (3) the availability and configuration of the species-specific ecological resources. To confirm that resource availability and configuration reflect habitat quality, we also assessed their impacts on individual morphology. Whatever the investigated spatial scale, our results quantitatively demonstrate the overall better performance of the resource-based habitat approach compared to other most commonly used approaches. Our analysis allowed us to assess the relative importance of each ecological resource in terms of both their availability and organization relative to the species' abundance, demography and individual fitness measures. Resource availability did not play the predominant role in defining habitat quality as it was in most cases overruled by resource organization. Finally, we confirmed the between-population transferability of the habitat definition and quality estimates while adopting a resource-based habitat approach. Our study clearly demonstrates the suitability of the resource-based definition of the habitat. Therefore, we argue that this approach should be favored for species of conservation concern. Although most conclusions so far have emerged from butterfly studies, the resource-based definition of the habitat should also be ecologically relevant to many other organisms.

International audience; Obtaining an accurate quantification of population size is often of prime importance in ecology and conservation biology (e.g. population viability analysis, a basic step for assessing species and population status in a given area and guiding effective conservation). When obtaining a reliable quantification of absolute (vs. relative) population size is required, Mark–Release–Recapture (MRR) is a method of choice for many organisms. This is a highly reliable but costly procedure in terms of time and potential impact on species and sites. Consequently, less costly alternatives are highly desirable for conservation and population ecologists.We present here a simplified MRR protocol to mitigate this cost of repeated MRR sampling with little compromise on the quality of the population size estimation. Using one of the largest existing butterfly MRR databases, collected on two fritillary species over a period of 20 years and >20 populations in Belgium, we assessed the possibility to reduce the effort of collecting MRR data while keeping accurate quantification of total population size. By downsampling from the full datasets and calculating a range of demographic census metrics, we specifically investigated whether marking individuals is necessary, and whether the number of sampling sessions can be reduced.We found that counting individuals is not enough: some individual marking, even in a simplistic way to differentiate newly recorded from previously seen individuals, is essential for estimating population size. A simple linear conversion function (number of “missed” individuals for each marked one) can be used to compute population size from the number of individuals marked over a small number of MRR sampling sessions. Parameterizing this function is system specific, because it depends on detectability of individuals, but only requires an initial effort of traditional high‐effort MRR in a few populations encompassing the expected range of population size, combined with previous knowledge on the species about potential factors affecting detectability.Our simplified MRR protocol should allow scientists to obtain absolute population size estimates almost as good as with traditional high‐effort MRR, but at a cost lowered in both the marking procedure and the intensity of field visits.

Most organisms are able to use social information to adjust key behaviours in their lifecycle including dispersal and cooperation. Ciliate microcosms provide a highly powerful tool to study the role of biocommunication in ecology and evolution because they allow simultaneous study of the chemical carriers of information and their eco-evolutionary consequences within short spatial and temporal scales. Here, we review what is known about the existence of social information use and its consequences on dispersal and cooperation in Tetrahymena, and point out the usefulness of Tetrahymena microcosms to further develop our understanding of the mechanisms and implications of information use in eco-evolutionary dynamics.

International audience; Boloria eunomia is a boreo-montane butterfly species suffering from habitat loss and isolation in the relictual part of its distribution range. Small populations persist in habitats scattered on plateaux or low mountains in western, central and southern Europe. Quantifying gene flow within and between these remnant populations is thus a crucial point to properly delineate metapopulations, to understand their dynamics and hence to design appropriate conservation plans for this butterfly species. We developed primers for the amplification of 15 microsatellites loci for B. eunomia. Thirteen loci were grouped in 2 multiplexes and amplified in 50 individuals from 5 populations to validate their use in population genetics. Gene diversity was on average 0.63 across populations. Null alleles and recurrent Hardy–Weinberg disequilibrium were detected in 7 loci. However, Fst estimates after correction for the presence of null alleles were highly correlated (0.91) to Fst estimates without correction. The loci developed here are thus usable for fine scale population genetic analyses and represent a very useful tool to quantify gene flow within and between metapopulations of B. eunomia.