Intrinsic Behavioral and Physiological Differences Among Laboratory Populations of Prairie Deermice

Abstract

The emphasis of this presentation is that social behavior is basically involved in the curtailment of growth of laboratory populations of prairie deermice through inhibiting influences on the reproductive development and function of population animals. Reproductive inhibition is not directly related to the numbers of animals present per se since physiological characteristics are similar between animals from populations differing widely in density under identical conditions of the physical environment. Thus, density should be interpreted relative to social or other behavioral factors and we should think of animals in a population in a qualitative as well as a quantitative sense. Population growth is controlled either by cessation of reproduction or by mortality of young and while 95% of the young remain reproductively immature and fail to reproduce, the weights and characteristics of their reproductive organs differ dependent upon the mechanism by which population growth is curtailed. Mechanisms of growth curtailment thus develop intrinsically to each population and involve communication through one or more of the senses of touch, smell, sight, hearing or taste. My data suggest that tactile cues from population animals (not necessarily overt aggression) may be of major importance in producing the reproductive retardation observed although chemosignals or other stimuli such as visual or auditory cues may act to slow reproductive recovery of inhibited animals. Data presented support the contention of a behavioral-physiological relationship distinct for each population.