The intricate web of interactions between hummingbirds and their food plants evolved over millennia as a result of diffuse co-evolution which has resulted in a remarkable array of morphological forms and functions. On-going human activities, such as deforestation and climate change, threaten these interaction webs, yet little is known as to how hummingbirds and their food plants will respond. This limitation derives from the fact that interactions are influenced by processes acting across a range of spatial and temporal scales — from local interactions occurring in a specific time and place to the evolution of life forms across millennia.
We are studying hummingbird-plant interactions across elevational gradients in three distinct biogeographic regions, the Talamanca Mountain Range (Costa Rica), the Andes Mountains (Ecuador) and the Atlantic Forest (Brazil). By combining extensive sampling, new conceptual approaches and rigorous statistical methods across these three biogeographic regions with distinct evolutionary histories we are bridging the gap between local interactions and evolutionary and biogeographic processes.
Species diversity, network structure (i.e. all pairwise interactions in the community) and community stability across the regions are the result of a mix of emergent mechanisms that act across hummingbird communities and as well local context dependent factors. For instance, trait-matching – considered in terms of trait barrier, that is the physical ability for a hummingbird to reach nectar in a flower, and trait-matching, measured as the similarity in flower tube length and hummingbird bill -influences the likelihood of a given hummingbird and plant interacting. Furthermore, trait-matching influences the overall network structure. However, these general mechanisms are not strictly followed in all local communities. At local scales and fine time intervals (i.e. a month) these broad mechanisms are somewhat modified by context dependent factors, such as the number of similar plant species flowering. These context dependent factors also influence plant-animal interactions allowing us to better understand why we see variation in broad mechanisms and begin to evaluate how future environmental changes might impact local communities.
