New Research Reveals How Human Impacts Are Rewiring Nature’s Food Webs
As the planet faces unprecedented environmental change, understanding how ecosystems respond is increasingly important. A new study, co-authored by the Centre for Ecosystem Management’s Charlotte Ward, Dr. Kevin McCann, and Dr. Kayla Hale, sheds light on a widespread ecological phenomenon.
Figure 1: A conceptual diagram of asymmetric rewiring. The spatial compartmentation of food webs combined with the differential impacts of anthropogenic pressures on distinct habitats drives asymmetric rewiring. In spatially compartmented food webs, lower trophic level organisms (blue and yellow circles) occupy distinct habitats (Habitat 1 and Habitat 2) while generalist consumers at higher trophic levels (black circles) forage across habitat boundaries, linking otherwise discrete energy pathways within food webs. As anthropogenic pressures, such as climate change, biological invasions, and land conversion, affect these habitats unevenly, they induce differential impacts that alter the topology (presence of circles and black arrows), interaction strengths (width of black arrows), and the size and quality of the nodes (size of circles) within the food web. For simplicity, the figure shows a generalist top predator coupling resources from two distinct habitats. As pressures intensify, the predator adjusts its foraging, causing shifts in the spatial structure of the food web, resulting in asymmetric rewiring.
Published in Ecology Letters, the research examines how human-driven pressures such as climate change, pollution, and land use are altering the underlying structure of ecosystems through a process the authors call the “asymmetric rewiring” of food webs. To explore this pattern, the team reviewed studies across terrestrial and aquatic ecosystems that employed stable isotope analysis (to trace energy sources in food webs), energetic food web modelling, and gut content analysis.
They show how these structural shifts can influence ecosystem resilience and key functions on which human societies depend—such as primary production at the base of the web (by terrestrial plants and algae) as well as secondary production at upper trophic levels (by larger predators).
By uncovering consistent patterns of asymmetric rewiring, this research offers a powerful new lens for understanding how food webs and the critical functions they support are broadly impacted by human activities.
Ward, C. A., Tunney, T. D., Donohue, I., Bieg, C., Hale, K. R. S., McMeans, B. C., Moore, J. C., & McCann, K. S. (2025). Global change asymmetrically rewires ecosystems. Ecology Letters. https://doi.org/10.1111/ele.70174