  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.
