Summary: Bioindicators of habitat quality and environmental change must be identified quantitatively and tested independently to confirm their usefulness. We used the indicator value (IndVal) method, which combines measures of habitat fidelity and specificity, to assess the indicator responses of dung beetles (Coleoptera: Scarabaeidae) in Tembe Elephant Park, South Africa. The indicator responses were verified by sampling in different areas of the Park, 2 years after the responses were originally quantified. We postulated that terrestrial insect indicators with different combinations of habitat specificity and fidelity might fulfil different indicator roles. Indicator species with strong habitat specificity (characteristic species) are unlikely to provide information on the direction of ecological change despite high vulnerability. Rather, detector species that span a range of ecological states are likely to be better in this role. We used IndVal for selecting such detector species that indicate the direction of ecological change. Sets of species were found to be robust bioindicators, i.e. reliably characteristic across the habitat of which they were indicative. The suite of indicators was refined by discarding those with IndVals that varied significantly across years, thus improving the confidence in the final suite of species selected. By clearly responding to a change in habitat between two ecological states, detector species provided information complementary to that provided by characteristic species. The IndVal method enabled both the identification and testing of indicator (characteristic and detector) species. Because of its resilience to changes in abundance, IndVal is a particularly effective tool for ecological bioindication. We conclude that both characteristic and detector species are useful bioindicators of habitat quality and conversion. We propose that bioindicators that are categorized and verified in this way will have valuable application in the monitoring of habitat integrity.

Areas of environmental transition, where ecological communities coincide, are sometimes termed ecotones. These regions often correspond with sharp environmental gradients. Ecotones occur at multiple spatial scales, ranging from transitions between biomes to local small-scale transitions. In recent years ecotones have received increasing scientific attention after being neglected for years, as studies historically often focused on distinct communities. However, it is still debatable whether these transitional regions are speciation and biodiversity hotspots that deserve special conservation interest or are actually areas that hold marginal populations that depend on other parts of the range for the maintenance of their biodiversity and therefore should not deserve primary investment. This paper discusses some of the recent advancements in our understanding of the role of ecotones in ecology, evolution, and conservation.

Aim: Beta diversity describes the variation in species composition between sites and can be used to infer why different species occupy different parts of the globe. It can be viewed in a number of ways. First, it can be partitioned into two distinct patterns: turnover and nestedness. Second, it can be investigated from either a species identity or a functional‐trait point of view. We aim to document for the first time how these two aspects of beta diversity vary in response to a large environmental gradient.Location: Maloti‐Drakensberg Mountains, southern Africa.Methods: We sampled ant assemblages along an extensive elevational gradient (900–3000 m a.s.l.) twice yearly for 7 years, and collected functional‐trait information related to the species’ dietary and habitat‐structure preferences. We used recently developed methods to partition species and functional beta diversity into their turnover and nestedness components. A series of null models were used to test whether the observed beta diversity patterns differed from random expectations.Results: Species beta diversity was driven by turnover, but functional beta diversity was composed of both turnover and nestedness patterns at different parts of the gradient. Null models revealed that deterministic processes were likely to be responsible for the species patterns but that the functional changes were indistinguishable from stochasticity.Main conclusions: Different ant species are found with increasing elevation, but they tend to represent an increasingly nested subset of the available functional strategies. This finding is unique and narrows down the list of possible factors that control ant existence across elevation. We conclude that diet and habitat preferences have little role in structuring ant assemblages in montane environments and that some other factor must be driving the non‐random patterns of species turnover. This finding also highlights the importance of distinguishing between different kinds of beta diversity.

Aim: In 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.Location: Africa, Australia and South America.Methods: We 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.Results: Assemblages 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 explainedc. 50% of the variation in lightness.Main conclusions: Our 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.