Effects of elevation and microclimatic temperatures on butterfly–flower interaction networks in a Mediterranean mountain range

Abstract Researching the properties of mutualistic networks over environmental gradients is a promising but underexplored means to test how global change can affect ecosystem assembly and functioning. We examined how elevation and microclimate influenced butterfly–flower interaction networks at the hottest time of the year in a Mediterranean mountain range. Throughout July 2023, we recorded weekly butterfly–flower interaction networks from 36 transects in nine sites, across an 800‐m elevation gradient in the Sierra de Guadarrama (Central Spain). We quantified metrics relating to network topology (modularity, nestedness), structural complexity (connectance, linkage density) and resilience to species loss (robustness, generality) and related these descriptors using generalised additive mixed models to elevation, microclimate temperature (modelled using Microclima) and time of day. The networks were dominated at all sites by one or two abundant butterfly and flower species, but these species varied with elevation. Butterfly networks in July were more robust at higher elevations to plant species loss. However, there were no clear effects of summer microclimatic temperatures on butterfly–plant networks, for which nestedness and modularity were low. Network properties also varied through the day, with connectance decreasing from morning to afternoon. In the Mediterranean mountains studied, summer butterfly–flower interaction networks appeared to show greater resilience to disturbance at high elevations. Nectar availability could become an important limiting factor for insects in a warming climate, and understanding the mechanisms influencing the properties of flower visitor networks is therefore likely to become increasingly important for adapting the conservation of insects to climate change.