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Aim\ud\udIn ectotherms, the colour of an individual's cuticle may have important thermoregulatory and protective consequences. In cool environments, ectotherms should be darker, to maximize heat gain, and larger, to minimize heat loss. Dark colours should also predominate under high UV-B conditions because melanin offers protection. We test these predictions in ants (Hymenoptera: Formicidae) across space and through time based on a new, spatially and temporally explicit, global-scale combination of assemblage-level and environmental data.\udLocation\ud\udAfrica, Australia and South America.\udMethods\ud\udWe sampled ant assemblages (n = 274) along 14 elevational transects on three continents. Individual assemblages ranged from 250 to 3000 m a.s.l. (minimum to maximum range in summer temperature of 0.5–35 °C). We used mixed-effects models to explain variation in assemblage cuticle lightness. Explanatory variables were average assemblage body size, temperature and UV-B irradiation. Annual temporal changes in lightness were examined for a subset of the data.\udResults\ud\udAssemblages with large average body sizes were darker in colour than those with small body sizes. Assemblages became lighter in colour with increasing temperature, but darkened again at the highest temperatures when there were high levels of UV-B. Through time, temperature and body size explained variation in lightness. Both the spatial and temporal models explained c. 50% of the variation in lightness.\udMain conclusions\ud\udOur results are consistent with the thermal melanism hypothesis, and demonstrate the importance of considering body size and UV-B radiation exposure in explaining the colour of insect cuticle. Crucially, this finding is at the assemblage level. Consequently, the relative abundances and identities of ant species that are present in an assemblage can change in accordance with environmental conditions over elevation, latitude and relatively short time spans. These findings suggest that there are important constraints on how ectotherm assemblages may be able to respond to rapidly changing environmental conditions.

1. Leaf-cutting ants (LCAs) are considered as one of the most important agents of soil disturbances that affect vegetation patterns, but these assertions are based on isolated studies or anecdotal data. In this study, meta-analysis techniques were used to quantitatively analyse the generality of these effects and determine some of their sources of variation. 2. The results reveal the following: (i) LCA nest sites showed higher levels of soil fertility than control sites, but the key source of these nutrients is the refuse material rather than the nest soil itself; (ii) refuse material from external piles tended to be richer in nutrient content than refuse material from internal refuse chambers; (iii) nest sites from temperate habitats showed higher cation content than those located in tropical/subtropical habitats; and (iv) nest sites showed higher plant growth than adjacent non-nest sites (especially if plants have access to the refuse) but similar plant density and plant richness. 3. As LCAs improve nutrient availability in nest sites through the accumulation of refuse material, the location of the refuse will have a relevant role affecting vegetation. LCA species with external refuse dumps could benefit herbs, early vegetation stages and short-living plants, whereas those with internal refuse chambers could benefit long-living, large trees. However, the positive effect on individual plants does not extend to population and community levels. The foraging preferences of ants and the changes in microclimatic conditions around nests could act as selective ecological filters. 4. As refuse material from external piles and nest sites in temperate habitats tend to show higher fertility than refuse material from internal nest chambers and nest sites in tropical/subtropical habitats, LCA species with external refuse dumps in temperate regions could be of particular relevance for nutrient cycling and vegetation patterns. Fil: Farji Brener, Alejandro Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación En Biodiversidad y Medioambiente; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio de Ecotono; Argentina Fil: Werenkraut, Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación En Biodiversidad y Medioambiente; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio de Ecotono; Argentina

1. Altitudinal gradients offer a unique scenario to elucidate how the increase in harsh climatic conditions towards the top of the mountain interacts with other environmental factors at regional and local scale to influence the spatial variation in local species composition and biodiversity maintenance. We analysed the altitudinal variation in the taxonomic composition of epigaeic beetle assemblages across five mountains in north-western Patagonia (Argentina) to address whether substantial change in species composition was associated (i) at regional spatial scale, with changes in vegetation types, and the presence of dry and moist mountains, and (ii) at local spatial scale, with variation in temperature, plant cover and richness and several soil characteristics. 2. We collected beetles using 486 pitfall traps arranged in fifty-four 100-m2 grid plots of nine traps settled at about 100 m of altitude apart from each other, from the base to the summit of each mountain. We used multivariate analyses to identify beetle assemblages and to evaluate their association with environment. 3. We identified different beetle assemblages, associated more with vegetation types rather than with mountains; indicator species showed higher degree of fidelity and specificity to vegetation types rather than to mountains. Local variation in temperature, plant cover and richness, and soil characteristics influence the variation in species composition. 4. Our study suggests the existence of a regional beetle fauna that is shared across these mountains. Major regional changes in vegetation types and local variation in environment drive the variation in the species composition of beetle assemblages at these latitudes. Fil: Werenkraut, Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación En Biodiversidad y Medioambiente; Argentina Fil: Ruggiero, Adriana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación En Biodiversidad y Medioambiente; Argentina