Ecological communities are continually reshaped by invasion, exclusion, and diversification, processes that naturally drive them toward the boundary of dynamical stability. Near such a boundary, a soft mode relaxes increasingly slowly and, under stochastic forcing, is expected to dominate the fluctuations, effectively reducing the dynamics to one dimension and generating strong positive and negative abundance correlations. Such correlations have therefore been proposed as signatures of an imminent transition. Here we show that this expectation can fail even arbitrarily close to criticality. The reason is that spectral softness does not guarantee stochastic visibility: the soft mode must receive enough environmental forcing to dominate the fluctuation background generated by the remaining modes. We demonstrate this mechanism in three ecological scenarios: a synthetic feasible community, a local community assembled by immigration from a regional pool, and a community generated by repeated diversification. In all three, communities approach marginal stability without developing the near-perfect pairwise correlations predicted by the single-mode picture. Thus, proximity to ecological criticality need not be visible in equal-time pairwise correlations.
The stability of an ecological community is conventionally defined through species interactions, which quantify how species affect one another. Interaction strengths are notoriously difficult to measure in species-rich assemblages. Long-term monitoring of species-rich communities, however, provides species abundance ti...
Alberto Megías, Vicente J. Ontiveros, David Alonso et al.· 0 citations
The complexity of many natural systems stems from the abundance of interactions that go beyond simple pairwise networks. While higher-order interactions (HOIs) are fundamental to the dynamics of complex networks, their role in shaping ecological communities through species dispersal remains poorly understood. Here, usi...
Arzoo Narang, P. Dutta· Physical Review E· 0 citations
Ecological interactions are often mediated by feedbacks between organisms and their resource environments. Yet, how resource supply dynamics dictate collective dynamical phases of an ecosystem remains unclear. Here, we analyse a generalised consumer–resource model with non-reciprocal interactions to demonstrate that se...
Jamila Rowland-Chandler, Akshit Goyal, W. Shou· bioRxiv· 0 citations
Classical models of pairwise species interactions consistently predict that large, complex communities are inherently unstable, yet the observed persistence of diverse communities highlights a central contradiction in theoretical ecology. While foundational frameworks often model species as homogeneous populations, one...
A hierarchical extension of the May-Leonard model, in which species interact through a directed predation chain while undergoing reproduction and mortality, is investigated, showing that the fully coexisting state is generically unstable, causing the dynamics to evolve toward lower-dimensional coexistence states.
Rakesh Samanta, Shraosi Dawn, Sk Jahiruddin et al.· 0 citations
When ecological communities experience environmental change, continued coexistence may require rapid adaptation to avoid extinction, i.e., evolutionary rescue. This rescue can be inhibited by competition. Combining Lotka-Volterra and population genetic models, we investigate how both within- and between-species competi...
Kuang-Yi Xu, Matthew M. Osmond· bioRxiv· 0 citations
We use cookies to run the site and, with your consent, for analytics and to show ads.
See our Cookie Policy.
