DYNAMICS OF AGE-STRUCTURED AND SIZE-STRUCTURED POPULATIONS IN FLUCTUATING ENVIRONMENTS - APPLICATIONS OF STOCHASTIC MATRIX MODELS TO NATURAL-POPULATIONS

Recent developments of the theory of stochastic matrix modeling have m ade it possible to estimate general properties of age- and size-struct ured populations in fluctuating environments. However, applications of the theory to natural populations are still few. The empirical studie s which have used stochastic matrix models are reviewed here to examin e whether predictions made by the theory can be generally found in wil d populations. The organisms studied include terrestrial grasses and h erbs, a seaweed, a fish, a reptile, a deer and some marine invertebrat es. In all the studies, the stochastic population growth rate (In lamb da(s)) was no greater than the deterministic population growth rate de termined using average vital rates, suggesting that the model based on ly on average vital rates may overestimate growth rates of populations in fluctuating environments. Factors affecting In lambda(s) include t he magnitude of variation in vital rates, probability distribution of random environments, fluctuation in different types of vital rates, co variances between vital rates, and autocorrelation between successive environments. However, comprehensive rules were hardly found through t he comparisons of the empirical studies. Based on shortcomings of prev ious studies, I address some important subjects which should be examin ed in future studies.