Body size plays an important role in predator-prey interactions, but its evolution is often limited due to all sorts of constraints. The arms race between bats and moths provides great opportunities to study body size evolution and associated traits across a wide range of species. Nocturnally-active moths are in particular limited in evolving larger bodies, as any increase in echo-acoustic reflective surface will put them more at risk of a bat's sonar system. Here we assessed whether moths can escape bat detection in a size-dependent way by increasing their acoustic camouflage through ultrasonic absorptive body scales. We used an automated setup to 3D scan a total of 110 moth specimen, from eight different families of Lepidoptera using a biomimetic bat head. We carried out three different ensonification experiments with intact, partially shaved and fully shaved moth specimen to relate the level of acoustic camouflage to various body size measurements. Comparing shaved versus intact specimen we found a clear reduction in target strength, although the effect strongly depends on frequency range as well as body size. The stealth coating provided by sound absorptive body scales can reduce prey detectability up to 365 cubic metres and is in particular beneficial to larger species. The level of acoustic camouflage did not covary with other anti-predator traits, such as ultrasonic ears and appears to be an all-round anti-predator strategy. Acoustic camouflage through stealth coating thus allows moths to escape from the allometric relationship between size and detection risk, thereby enabling species to evolve larger bodies.

Community assembly theory proposed a hierarchy by which local composition is determined by both regional processes, e.g. dispersal and migration, and local processes, e.g. local filtering by environmental conditions and competition. How these factors interact and combined govern local species assembly and trait composition is poorly known. Thereto, we propose a conceptual model in which strong dispersal ability (linked to low environmental tolerance) is fitness-dependent, promoting species to track environmental changes; weak dispersal (linked to high tolerance) should be fitness-independent, enhancing the influence of competition. Conquently, local trait dissimilarity should have a positive humpback shape, while regional trait dissimilarity should have an upturned-humpback relationship with a dispersal trait gradient. We found strong empirical support for this concept in trait distribution patterns of stream macroinvertebrates from five basins across China. These findings are discussed in terms of metacommunity theory and merit further testing of our concept across ecosystems and organism worldwide.

Rapid environmental change forces long-lived plants like trees to immigrate into zones still occupied by phylogenetically distantly related species. Does such phylogenetic isolation (PI) change the trees’ ecosystem functioning such as litter decomposition? We studied oaks (Quercus petraea) of low and high PI, reciprocally transplanting their litters to identify effect of aboveground litter quality and belowground decomposer biota. Across 8 and 14 months we quantified decomposition (mass loss, C-loss and N-loss), decomposer biota (Acari, Collembola, microbes) and 13C/12C ratio. Across 14 months, aboveground PI retarded decomposition (mass and C loss). Across 8 and 14 months, above- and belowground PI extensively altered relationships between decomposition and abundances/diversities of different soil biota, reduced microbial activity and 13C/12C ratios. Overall, coexistence of trees with distant relatives impedes and severely re-organizes C and N recycling. Such negative ecosystem feedback might prevent trees from tracking and conserving abiotic niches under environmental change.