Dispersal, disease and life-history evolution

Discrete-time susceptible-infective-susceptible (S-I-S) disease transmissio n. models can exhibit bistability (alternative stable equilibria) over a wi de range of parameter values. We illustrate the richness generated by such 'simple' non-linear systems in the study of two patch epidemic models with disease-enhanced or disease-suppressed dispersal. Dispersal between patches can have a profound impact on local patch disease dynamics. In fact, dispe rsal between patches may give rise to bistability in parameter regimes with out bistability in single patch models. (C) 2001 Elsevier Science Inc. All rights reserved.