Metapopulation Persistence in Cellular Automata

This thesis uses spatially distributed models to test the Metapopulation Hypothesis, which asserts that migration between local populations promotes the persistence of a regional “metapopulation” despite short-term local fluctuations, or even temporary local extinctions, on the local scale. A review of relevant models finds that:1. These models found nothing to disagree with the hypothesis. Sub-division and migration promotes persistence and prevents extinction. 2. The size of the area that a population occupies affects its long-term survival, independently of population density inside that area. A population in too small an area, even with a normal population density, leads to extinction. 3. Explicit stochasticity (corresponding to random environmental fluctuations or “noise”) promotes persistence in certain models of distributed populations; however, deterministic models without stochasticity give similar outputs because they are chaotic, which indicates that environmental fluctuations play a small rôle as a mechanism for promoting persistence of populations.