What is it about?

We show that indirect ecological effects—changes passed through the environment or other species—can be strong enough to drive adaptive evolution across habitat boundaries. In outdoor pond experiments, aphids eating floating duckweed altered water conditions in ways that changed phytoplankton and, in turn, drove evolutionary changes in water fleas (Daphnia magna). This provides direct empirical evidence that species which never interact physically can still shape each other’s evolution.

Featured Image

Why is it important?

Evolutionary biology often emphasizes direct interactions (predation, parasitism). Our results demonstrate that indirect interactions can also reshape species' evolution even when species live in different habitats. This has implications for ecosystem management, conservation, and forecasting under global change, where actions in one part of a food web—or even one habitat—can affect the evolution of another.

Perspectives

This project began with simple natural-history observations. We first watched duckweed and algae compete for light and nutrients. During fieldwork, we then saw aphids feeding on duckweed, while Daphnia were grazing on algae. These linked observations suggested a straightforward interaction chain—aphids → duckweed → algae → Daphnia—and posed a clear question: could herbivory on macrophytes indirectly alter algal conditions and drive adaptive change in Daphnia? Testing this required the combined expertise of three teams, each specializing in aphids, duckweed, or Daphnia. Coordinating fieldwork, husbandry, phenotyping, sequencing, and analysis was demanding, but integrating these strengths allowed us to trace the signal from natural history to mechanism. For me, this paper shows how careful observation in nature can spark interesting hypotheses—and how focused collaboration turns them into evidence.

Shuqing Xu
Johannes Gutenberg University Mainz

Read the Original

This page is a summary of: Aphid herbivory on macrophytes drives adaptive evolution in an aquatic community via indirect effects, Proceedings of the National Academy of Sciences, August 2025, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2502742122.
You can read the full text:

Read

Resources

Contributors

The following have contributed to this page