#20 · Systems biology

Effective models reduce birth-death, epidemic, and replicator population dynamics

The dominant thread is the reduction of stochastic or evolutionary dynamics to effective descriptions with interpretable parameters. The asymmetrically regulated birth-death study derives an effective population size and fixation results applicable to T-cell clones. The antigenic-variant study shows that population immunity carried over from past epidemics shapes recurrent epidemics according to the antigenic similarity of new variants. The alternating-environment study shows that a species losing in both environments can persist if it switches fast enough, with implications for alternating drug failure. The replicator study applies a two-timescale model of evolving fitness landscapes with an LP-based algorithm on four canonical systems. These works do not share a single mechanism; the shared element is the reduction strategy. New here are the explicit two-timescale, LP-based treatment of non-degenerate replicator landscapes and the effective population size derived for asymmetric regulation.