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Aim: Ecological gradients are expected to be associated with structural rewiring of species interaction networks. The study of network structures along geographic and ecological gradients, however, remains marginal because documenting species interactions at multiple sites is a methodological challenge. Here, we aimed to study the structural variation in plant–herbivore interaction networks along elevational gradients using molecular metabarcoding. Location: European Alps. Taxon: Plant and Orthopteran herbivores. Methods: We used a standardized DNA metabarcoding method applied to Orthopteran faeces to document the structure of 48 networks of species interactions across six elevational gradients. We examined how structural properties of plant–Orthoptera networks reflecting specialization and robustness vary with elevation. We compared observed variation to null models to account for differences in network size. Results: We found an increase in the levels of generality and nestedness with decreasing temperature, and the correlation was stronger than in null models. These relationships corresponded to greater robustness and reduced the importance of specific keystone species in alpine habitats compared to lowland grasslands. Main conclusions: In cold environments, plant–herbivore networks are wired in a way that may reinforce the resilience of the system to species extinction. Documenting ecological networks along ecological gradients allows a better understanding of the influence of climate on the structure of ecological communities. [ABSTRACT FROM AUTHOR]

Aim In interaction with past climate changes, it is likely that plate tectonics contributed to the shaping of current global species diversity, but so far this has not been statistically quantified at the global level. Here, we tested whether plate tectonics since the breakup of Gondwana left an imprint on current patterns of species richness of amphibians, birds and mammals. Location Global. Methods We reconstructed the absolute positions of continental plates since the Early Cretaceous and used this information to derive variables of latitudinal shifts and potential exchanges among landmasses that could have modulated species richness. Using a multi-model inference approach combining both contemporary and historical variables, we quantified the relative importance of variables related to plate tectonics in explaining the spatial variation of the richness of amphibians, birds and mammals. Next, we employed a moving window approach to test whether plate tectonics left a more marked imprint in specific regions. Results Plate tectonics left an imprint on current patterns of vertebrate species richness in geologically singular regions, especially in the Indo-Australian Archipelago and the region comprising eastern Africa and Madagascar. For birds and mammals, but not amphibians, we found a marked contrast in species richness across Australia and Southeast Asia and eastern Africa and Madagascar associated with plate tectonics. Moreover, the relationship between species richness and plate tectonics varied across taxonomic orders for birds and mammals. Main conclusions While no general imprint of plate tectonics was detected at the global scale, our regional analysis highlighted a substantial role of geodynamics in shaping current patterns of vertebrate species richness in Southeast Asia and Madagascar. Future studies should integrate the full range of processes associated with plate tectonics, including orogeny, not considered here. [ABSTRACT FROM AUTHOR]

Aim High intra-specific genetic diversity is necessary for species adaptation to novel environments under climate change, but species tracking suitable conditions are losing alleles through successive founder events during range shift. Here, we investigated the relationship between range shift since the Last Glacial Maximum ( LGM) and extant population genetic diversity across multiple plant species to understand variability in species responses. Location The circumpolar Arctic and northern temperate alpine ranges. Methods We estimated the climatic niches of 30 cold-adapted plant species using range maps coupled with species distribution models and hindcasted species suitable areas to reconstructions of the mid-Holocene and LGM climates. We computed the species-specific migration distances from the species glacial refugia to their current distribution and correlated distances to extant genetic diversity in 1295 populations. Differential responses among species were related to life-history traits. Results We found a negative association between inferred migration distances from refugia and genetic diversities in 25 species, but only 11 had statistically significant negative slopes. The relationships between inferred distance and population genetic diversity were steeper for insect-pollinated species than wind-pollinated species, but the difference among pollination system was marginally independent from phylogenetic autocorrelation. Main conclusion The relationships between inferred migration distances and genetic diversities in 11 species, independent from current isolation, indicate that past range shifts were associated with a genetic bottleneck effect with an average of 21% loss of genetic diversity per 1000 km−1. In contrast, the absence of relationship in many species also indicates that the response is species specific and may be modulated by plant pollination strategies or result from more complex historical contingencies than those modelled here. [ABSTRACT FROM AUTHOR]