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Aim There has been a wide interest in the effect of biotic interactions on species' occurrences and abundances at large spatial scales, coupled with a vast development of the statistical methods to study them. Still, evidence for whether the effects of within-trophic-level biotic interactions (e.g. competition and heterospecific attraction) are discernible beyond local scales remains inconsistent. Here, we present a novel hypothesis-testing framework based on joint dynamic species distribution models and functional trait similarity to dissect between environmental filtering and biotic interactions. Location France and Finland. Taxon Birds. Methods We estimated species-to-species associations within a trophic level, independent of the main environmental variables (mean temperature and total precipitation) for common species at large spatial scale with joint dynamic species distribution (a multivariate spatiotemporal delta model) models. We created hypotheses based on species' functionality (morphological and/or diet dissimilarity) and habitat preferences about the sign and strength of the pairwise spatiotemporal associations to estimate the extent to which they result from biotic interactions (competition, heterospecific attraction) and/or environmental filtering. Results Spatiotemporal associations were mostly positive (80%), followed by random (15%), and only 5% were negative. Where detected, negative spatiotemporal associations in different communities were due to a few species. The relationship between spatiotemporal association and functional dissimilarity among species was negative, which fulfils the predictions of both environmental filtering and heterospecific attraction. Main conclusions We showed that processes leading to species aggregation (mixture between environmental filtering and heterospecific attraction) seem to dominate assembly rules, and we did not find evidence for competition. Altogether, our hypothesis-testing framework based on joint dynamic species distribution models and functional trait similarity is beneficial in ecological interpretation of species-to-species associations from data covering several decades and biogeographical regions. peerReviewed

II.AbstactThe ecology of social information use has been studied in many intra- and interspecific contexts, while the evolutionary consequences of social information use remain less understood. Furthermore, selective social information use, where individuals are discriminative in their decision-making on how to use social information, has been overlooked in interspecific context. In particular, the intentional decision to reject a behavioural trait observed via social information, has gained less attention, although it has recently been shown to occur in various taxa. We develop an individual-based simulation model to explore in which circumstances social information use leads to different coevolutionary outcomes among populations of two species. The initial phenotypes and the balance between costs of competition and benefits of social information use determine whether selection leads to trait divergence, convergence or coevolutionary arms race between two species. Based on existing literature, we propose that selective decisions of individuals, including active rejection, may have far-reaching fitness consequences, potentially leading to similar evolutionary consequences among the populations of the information source and the user as predicted by our model. Overall, we argue that the eco-evolutionary consequences of selective interspecific social information use may be much more prevalent than thus far considered.

AimThe impact of global change on biodiversity is commonly assessed in terms of changes in species distributions, community richness and community composition. Whether and how much associations between species, i.e. the degree of correlation in their spatial co-occurrence, are also changing is much less documented and mostly limited to local studies of ecological networks. In this study, we quantify changes in large-scale patterns of species associations in bird communities in relation to changes in species composition.LocationFrance.Time period2001-2017.Major taxa studiedCommon breeding birds.MethodsWe use network approaches to build three community-aggregated indices reflecting complementary aspects of species association networks. We characterise the spatio-temporal dynamics of these indices using a large-scale and high-resolution dataset of bird co-abundances of 109 species monitored for 17 years (2001-2017) from 1,969 sites across France. We finally test whether spatial and temporal changes in species association networks are related to species homogenisation estimated as the spatio-temporal dynamics of β-diversity and the proportion of habitat generalists. The consistency of these relationships is tested across three main habitats, namely woodland, grassland and human settlements.ResultsWe document a directional change in association-based indices in response to modifications in β-diversity and in the proportion of generalists in space and time. Weaker associations and sparser networks were related to lower β-diversity and a higher proportion of generalists, suggesting an overlooked aspect of biotic homogenisation affecting species associations. We report that this overall pattern is not constant across habitats, with opposite relationships between biotic homogenisation and change in species association networks in urban versus forest communities suggesting distinct homogenisation processes.Main ConclusionsAlthough species association contain only partial signatures of species interactions, our study highlights that biotic homogenisation translates to finer changes in community structure by affecting the number, strength and type of species associations.

Island populations are frequently smaller than continental populations, have lower genetic diversity, are more inbred and show genetic differentiation from the mainland ones. However, sufficient numbers of immigrants may reduce the differentiation of insular populations and moderate the effects of genetic drift. In this study, we compared insular and continental populations of Cetti’s Warbler Cettia cetti and Great Reed Warbler Acrocephalus arundinaceus. We assessed the degree of genetic differentiation between insular and continental birds, their demographic history and genetic diversity. We compared the results, taking into account the differences in migration strategy and morphology of the two warblers. We found slightly lower genetic diversity in the insular populations than in the continental birds, possibly because of the lower population size or reduced immigration. The genetic differentiation between island and mainland birds was low, but higher in Cetti’s Warbler than in the Great Reed Warbler, suggesting differences in the species’ capability of crossing the sea. We found evidence for a past bottleneck in both the insular and continental populations of Cetti’s Warbler, while for the Great Reed Warbler we found no signs of past population reductions. A high dispersal capability of the Great Reed Warbler may have allowed high gene flow, which may explain the observed interspecific differences in the demographic history of the Great Reed Warbler and Cetti’s Warbler.