Environmental adaptation by annual plants (an optimal control/games viewpoint)

Abstract

As with all living things, annual plants have different ways of adapting to the environment. Adaptation may occur via: (1) physiological versatility, (2) developmental flexibility and (3) genetic evolution. Adaptation (1) is associated with a rapid response to short term changes in the environment, such as the opening or closing of the stomata in the leaves of plants with a change in the ambient temperature or humidity. Adaptation (2) is associated with response due to a more long term conditioning by the environment, such as limited flowering of a plant due to a dry season. Adaptation (3) is the genetic adaptation in response to particular semi-permanent conditions in the environment. If these conditions should change, then it may take several seasons to produce a new genetic adaptation.

Adaptations (2) and (3) are examined here in the context of two different habitats, that of growth under limited nutrient and growth under limited sunlight. The viewpoint is taken that survival is a direct consequence of maximizing seed production.

In the limited nutrient habitat, it is assumed that a nutrient conversion efficiency represents a control parameter subject to genetic selection. In the limited sunlight habitat, it is assumed that the percent allocation of total growth into seeds is a control variable subject to developmental flexibility. In each case, controls which result in maximum seed production are determined. Results are compared between a monoculture and a mixture of two different species.