Population viability analyses with demographically and spatially structured models

This paper presents a review of demographically structured (or, frequency-based) models, in which the individuals in a population are grouped into distinct classes. Structured models are used when vital rates (survival, reproduction, dispersal) of individuals depend on their age or physiological/morphological stage. Variation in these rates (environmental stochasticity) and the effect of abundance (density dependence) are important factors that determine population viability. Metapopulation models are built by adding information about spatial structure (number of populations, and the location, size, shape, and quality of habitat patches they inhabit). At the metapopulation level, the similarity of environmental fluctuations (correlation) and dispersal among patches become important variables determining viability. These modeling methods can be combined with habitat analyses that link landscape data with metapopulation models.