Fruit traits have the potential to influence disperser communities and vice versa. Here we examine the trends in three fruit traits related to dispersal by frugivores: diameter, colour and presentation (i.e. location of displayed fruits on the trunk or on the branches) along a 200 – 2700 m asl rainforest elevation gradient in Papua New Guinea. We found fruit diameter to be lower at higher elevations. While specific fruit colours showed few strong elevational patterns, colours typically attributed to attracting avian dispersers were more prevalent at higher elevations. The proportion of ramiflorous species (bearing fruits from branches) increased with elevation. Finally, we use phylogenetic information to test the “dispersal syndromes” hypothesis: that combinations of fruit traits have evolved in accordance with the preferences and sensory abilities of different frugivore guilds. All fruit traits except presentation showed little evidence of phylogenetic signal but we found fruits displaying colours attributed to mammal frugivory to be larger than “bird colour” fruits. We found evidence for the correlated evolution of fruit size and colour, in support of the dispersal syndromes hypothesis.

Climate change poses a severe threat to many taxa, with increased mean temperatures and frequency of extreme weather events predicted. Insects respond to non-optimal temperatures using behaviours or local microclimates to thermoregulate (thermal buffering ability), or through physiological tolerance. We studied the thermal buffering ability and thermal tolerance of a community of 54 butterfly species in Panama. Thermal buffering ability and tolerance were influenced by family, size, and colour, with Pieridae, large, and dark butterflies having the strongest thermal buffering ability, and with Hesperiidae, small, and dark butterflies tolerating the highest temperatures. We identified an interaction between thermal buffering ability and physiological tolerance, where species with stronger thermal buffering abilities had lower thermal tolerance, and vice versa. This interaction implies that most species will be vulnerable to climate change to an extent, considering that species appear to adapt to one strategy at the expense of the other.

Urbanization is recognized as an important driver of the diversity and abundance of tree associated insect herbivores, but its consequences for insect herbivory are controversial. A likely source of variability among studies is the insufficient consideration of intra-urban variability in forest cover. With the help of citizen scientists, we investigated the independent and interactive effect of urbanization and local canopy cover on insect herbivory in the pedunculate oak (Quercus robur) throughout most of its geographic range in Europe. The damage caused by chewing insect herbivores as well as the incidence of leaf-mining and gall-inducing herbivores consistently decreased with increasing urbanization around focal oaks. Herbivory by chewing herbivores increased with increasing forest cover, regardless of urbanization. In contrast, an increase in local canopy cover buffered the negative effect of urbanization on leaf-miners and strengthened its effect on gall-inducers. These results show the complexity of plant-herbivore interactions in urbanized areas, highlighting that the presence of local canopy cover within cities has the potential to attenuate or modify the effect of urbanization on biotic interactions.

Current climate change is disrupting biotic interactions and eroding biodiversity worldwide. However, species sensitive to drought, high temperatures and climate variability might persist in microclimatic refuges, such as leaf shelters built by arthropods. We conducted a distributed experiment across an 11,790 km latitudinal gradient to explore how the importance of leaf shelters for terrestrial arthropods changes with latitude, elevation and underlying climate. Our analyses revealed leaf shelters to be key facilitative elements for the diversity of arthropods. Predator diversity and overall biomass within shelters increased with local drought and temperature variability, regardless of latitude and elevation. In contrast, shelter usage by herbivores increased with abundance of predators on those same plants and in wetter climates. Projected increase in climatic variability and drought in certain geographic regions is therefore likely to enhance the importance of biotic refuges, especially for predators, in mitigating the impact of climate change on species persistence.

In tritrophic interactions, birds are able to detect herbivore-induced plant volatiles and use them as a signal of presence of arthropods on plant. It remains unclear whether this ability is innate or learned and how the birds react to novel odours. We studied whether and how naïve and trained great tits (Parus major) discriminate between herbivore-induced and noninduced saplings of potentially familiar and novel plant species. Birds trained to discriminate between saplings of either novel or familiar plant species preferred the induced saplings of the plants species they were trained to. Naïve birds did not show any preferences. Our results indicate that the attraction of great tits to herbivore-induced trees is not innate. Yet, the skill can be acquired through learning and novelty of the odour doesn’t seem to be important. This implies that birds are learning whole bouquets of the herbivore-induced volatile compounds, rather than specific compounds individually.