#3 · Systems biology

Bifurcation structure and heterogeneity determine persistence beyond threshold indices

The dominant thread is that persistence outcomes in these models depend on structural features rather than a single threshold quantity. The black Sigatoka host-pathogen model exhibits backward bifurcation, so persistence can occur when the threshold quantity is below one, and sensitivity and stochastic analyses identify its persistence drivers. A spatial study uses a competitive-balance metric to show that dispersal diversity lowers species vulnerability to local extinction. A published model of microbial generalist and specialist strategies under stochastic feast-famine supply attributes population outcomes to growth-death trade-offs. These items are heterogeneous in system, spanning pathogens, ecological communities, and microbial populations, so the shared element is structural determinants of persistence. What is new is explicit treatment of bifurcation structure and dispersal or nutrient-supply heterogeneity as persistence determinants, rather than threshold indices alone.