A SIMPLE STOCHASTIC-MODEL OF RESOURCE-LIMITED INSECT POPULATIONS

A simple stochastic model for resource-limited populations is proposed and its properties examined by simulations. Features of the model are an explicit resource-limit. which cannot be exceeded, and a realised population growth-rate which is influenced by resource availability. I n a range of simulations, the size and variability of resource levels and growth-rates were varied, but the pattern of variability of each p arameter was kept the same. At most resource-levels and growth-rates c onsidered, the model populations showed the general synchrony typical of many monitored butterfly populations and also showed strong synchro ny between fluctuations in resource level and population size. As reso urce-levels and/or population growth-rates declined, both types of syn chrony were eventually lost as the model populations became highly uns table and liable to extinction. Other properties of the model are disc ussed and contrasted with classical population models based on differe nce equations.