Mathematical model of consumer homeostasis control in plant-herbivore dynamics

Consumers must regulate the elemental composition of body tissue at ratios that differfrom those of their food. This problem of elemental homeostasis is especially acute for herbivores for which elemental composition of food does not equal that of the consumer and changes widely throughout the lifespan. We extend work of Sterner [1] and Frost and Elser [2] using a dynamic model of homeostatic control within tolerance limits by consumers feeding on unbalanced diets based on nonlinear assimilation as a primary mechanism. Differential assimilation provides a suitable, if incomplete, mechanism for homeostasis where the limiting element defines the accumulation trajectory of nutrients incorporated into the consumer.