Environmental Constraints on Some Predator—Prey Interactions

Abstract

The study of environmental relationships of living organisms has a long history. Environmental effects on animals were reported by Davenport and Castle (1896). Early work on reptiles was done by Atsatt (1939) and by Cowles and Bogert (1944). Quantitative engineering approaches to the energy balance of humans first began appearing with the work of Hardy and DuBois (1938). The extension of energy-balance modeling to outdoor situations and nonhuman animals was firmly established with the publication of papers by Bartlett and Cates (1967) and Norris (1967). Porter and Gates (1969) made some initial efforts to generalize energy-balance calculations for a variety of animals. Their development of a climate-space niche was useful in expressing physiological limits of animals as they related to various combinations of environmental parameters. But the concept is limited because, first, it is a steady-state model; second, animals rarely live at their physiological limits; and third, microhabitats available in time and space are not specified. Although a climate-space diagram represents a useful concept, ecological and behavioral limits needed to be defined. Transient energy-balance models were needed and had to include more biology along with physics and engineering. Microhabitat specification was needed. Tests needed to be done on live animals in both controlled environmental facilities and out of doors. Recently, these things have been done for a relatively simple desert environment and a desert lizard, Dipsosaurus dorsalis (Porter et al., 1973). This paper outlines the usefulness of energy-balance concepts to examine predator—prey relationships. It is the basis for the extension of our investigations to other predator—prey systems, one of which we describe here. We shall attempt only a semiquantitative description here since the equations and experiments testing them have been published elsewhere.