Population and community ecology need a large-scale perspective because local patterns (of biodiversity) and processes (trophic interactions) are influenced by the regional setting. The ratio of the foraging range and/or dispersal ability to the distance between landscape elements influences local population dynamics. The spatial scale experienced by a species may be linked to its trophic level and also to traits such as body size, resource specialization, rarity, and population size variability. Hence, communities are assemblages of species with different spatial strategies. Effects of habitat loss and habitat fragmentation on plant-herbivore, herbivore-enemy, as well as plant-pollinator interactions are contingent on species and landscape. Metapopulation theory provides a unifying frame to approach plant-insect systems across fragmented landscape, although the landscape context is often ignored. In some cases theory is far ahead of empirical research. We call for more population data on large spatial and temporal scales to better understand plant-insect populations across fragmented landscapes.

The factors determining gradients of biodiversity are a fundamental yet unresolved topic in ecology. While diversity gradients have been analysed for numerous single taxa, progress towards general explanatory models has been hampered by limitations in the phylogenetic coverage of past studies. By parallel sampling of 25 major plant and animal taxa along a 3.7 km elevational gradient on Mt. Kilimanjaro, we quantify cross-taxon consensus in diversity gradients and evaluate predictors of diversity from single taxa to a multi-taxa community level. While single taxa show complex distribution patterns and respond to different environmental factors, scaling up diversity to the community level leads to an unambiguous support for temperature as the main predictor of species richness in both plants and animals. Our findings illuminate the influence of taxonomic coverage for models of diversity gradients and point to the importance of temperature for diversification and species coexistence in plant and animal communities.

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Associations between biological traits of animals and climate are well documented by physiological and local-scale studies. However, whether an ecophysiological phenomenon can affect large-scale biogeographical patterns of insects is largely unknown. Insects absorb energy from the sun to become mobile, and their colouration varies depending on the prevailing climate where they live. Here we show, using data of 473 European butterfly and dragonfly species, that dark-coloured insect species are favoured in cooler climates and light-coloured species in warmer climates. By comparing distribution maps of dragonflies from 1988 and 2006, we provide support for a mechanistic link between climate, functional traits and species that affects geographical distributions even at continental scales. Our results constitute a foundation for better forecasting the effect of climate change on many insect groups.