Stochastic development of individual members of a population: a Brownian motion approach.

The paper looks at a formulation of physiologically structured population models within which individual development is affected by a special form of demographic stochasticity, accounting for random success or failure at exploiting available resources. This frees models from the requirement that individual development is uniquely determined by physiology and environmental conditions. An expression is derived which describes the motion of cohorts through individual state space, and the results are applied to an idealized model of Daphnia feeding on algae.