Periodic Reporting for period 4 - Ecol of interactions (Developing the predictive ecology of plant-animal interactions across space and time)
Reporting period: 2023-04-01 to 2025-03-31
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.
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.
We systematically sampled 39 sites across ~2 years and 3 elevational gradients in three countries. This effort resulted in 95,824 interactions between 715 plants and 79 hummingbird species, and also 873 interactions with another 12 bird species in Ecuador. We have a data paper in review at Ecology. Based on these data, and other related data collected during the project, we published 51 peer reviewed papers (more are submitted and in preparation), 12 outreach publications and gave numerous talks to both the general public and scientific community.
Plant-hummingbird interactions are the basis for an important ecosystem service: pollination. The results obtained in this project provide valuable information on how interactions are affected by human induced land-use change. Further sampling occurred across an elevational gradient, which can serve as a space for time substitution to begin to evaluate the influence of climate change. Our results on the importance of general rules (such as trait-matching) and context dependent factors (such as local flower abundance) provides science-driven guidance for conservation and restoration. For example, in Ecuador restoration activities are directly using the results of our work. More generally, advancing knowledge of the mechanisms influencing interactions will us help anticipate how on-going environmental change might change these interactions and the resulting ecosystem services.