A physiological profile approach to animal temperament: How to understand the functional significance of individual differences in behaviour

Abstract

Animal behaviour research has experienced a renewed interest in consistent individual differences (i.e. animal personality or temperament). Recent ecological studies have identified environmental conditions that give rise to the development and evolution of temperaments and to fitness-related outcomes of temperament. Additional literature has also described relationships between temperaments and physiological regulation. However, one-to-one relationships between one behavioural trait and one physiological system do not account for co-selection of behavioural and physiological traits, nor the complex signalling among physiological systems. In the current paper, we review the literature on multiple physiological processes associated with temperament, propose temperament-specific physiological profiles, and focus on next steps to understand the functional significance, evolution and maintenance of temperaments. We propose that to understand causes and consequences of temperament we need to characterize integrative physiological profiles associated with different temperaments.

Keywords: animal personality; behavioural consistency; behavioural syndromes; fitness; physiological profiles; temperament.

Figure 1.

Expected physiological profiles for exploration, sociability, boldness and aggression. For each temperament, the grey shading indicates the relative regulation that we might expect of each physiological system (sympathetic reactivity, HPA reactivity, basal HPA activity, innate immunity, cell-mediate immunity and humoral immunity). Grey shading, within any particular physiological system, that extends to the outer-most ring indicates upregulation of that physiological system, while shading that only extends out one ring from the centre indicates downregulation of that system. Shading that reaches the middle ring indicates neither up- nor downregulation of that physiological system. We present hypothetical physiological profiles for the four temperaments that have been most frequently studied.