Dynamics of a producer-parasite ecosystem on the brink of collapse

TL;DR

This study investigates how complex producer-parasite ecosystems exhibit critical slowing down before collapse, emphasizing the importance of analyzing coupled population dynamics over simple population size measures for early warning signals.

Contribution

It demonstrates that ecosystem collapse can be predicted by slowing dynamics in coupled populations, even when individual population sizes increase unexpectedly.

Findings

Ecosystem dynamics slow down near collapse despite population growth.

Coupled population analysis provides early warning signals.

Population size alone can be misleading as an indicator of stability.

Abstract

Ecosystems can undergo sudden shifts to undesirable states, but recent studies with simple single species ecosystems have demonstrated that advance warning can be provided by the slowing down of population dynamics near a tipping point. However, it is not clear how this effect of critical slowing down will manifest in ecosystems with strong interactions between their components. Here we probe the dynamics of an experimental producer parasite ecosystem as it approaches a catastrophic collapse. Surprisingly, the producer population grows in size as the environment deteriorates, highlighting that population size can be a misleading measure of ecosystem stability. By analyzing the oscillatory producer parasite dynamics for over ~100 generations in multiple environmental conditions, we found that the collective ecosystem dynamics slows down as the tipping point is approached. Analysis of the coupled dynamics of interacting populations may therefore be necessary to provide advance warning of collapse in complex communities.