Environmental fluctuations: How do they affect the topography of the adaptive landscape?

Abstract

A Phenotypic Adaptive Landscape is defined with fitness as the ordinate, and longevity of the juvenile phase and duration of disturbances to the adult phase as the horizontal axes. The effect of local environmental perturbations on the landscape’s shape is studied using a semistochastic population model. In this model the intrinsic population dynamics takes the form of a differential-delay nonlinear equation and the environmental disturbance appears as a multiplicativetelegraphic noise. We demonstrate that the landscape has no single characteristic scale. Rather, it shows adaptive peaks corresponding to an integer relation between the biological and the environmental periodicities. Since the system is constrained by a finite time and a finite physiological range, the landscape may have different topographies for different local environmental regimes. A very simple fully deterministic model is presented, predicting landscapes that are similar to those obtained by the semistochastic model. Application to life history strategies are discussed.