Diversity-Stability Hypothesis

The diversity-stability hypothesis is the claim that more diverse systems — whether ecosystems, economies, or epistemic communities — are more stable in the face of disturbance. In ecology, the hypothesis predicts that species-rich communities resist invasion, recover faster from perturbation, and maintain productivity more reliably than species-poor communities. The mechanism is functional redundancy: if multiple species perform similar ecological roles, the loss of any one does not collapse the function. The hypothesis has been extended beyond biology to systems theory, economics, and network epistemics, where it becomes the claim that diversity of models, methods, or information sources stabilizes a system against shocks.

The hypothesis is not universally confirmed. Robert May's 1972 mathematical models showed that under certain conditions, increasing diversity actually decreases stability — a result that launched decades of debate about whether the hypothesis is true, false, or context-dependent. The resolution depends on what kind of diversity and what kind of stability are measured. Species diversity may not stabilize a community if the species are functionally similar; functional diversity may stabilize it even if species richness is low. Similarly, in network epistemics, a community with many researchers using the same flawed method is not epistemically diverse, no matter how many researchers there are. The hypothesis survives, but only when diversity is understood as heterogeneity of response mechanisms rather than mere numerical variety.