Individual variation in stage duration in matrix population models: Problems and solutions

Matrix population models are widely used to describe the growth of stage-structured populations. The variability in stage duration among individuals is one of the important parameters affecting population growth. Despite that importance, studies frequently focus only on the average duration and (perhaps unknowingly) make specific assumptions regarding the variation in stage duration that likely contradicts with the data. Furthermore, although there are methods for modeling variable stage duration, they are not sufficiently flexible to encompass the diversity of potential distributions. This study discusses problems associated with the existing methods and describes approaches to deal with the problems.