Behavioral Syndromes: A Behavioral Ecologist’s View on the Evolutionary and Ecological Implications of Animal Personalities

Abstract

Recent years have seen an explosion of interest in animal personalities (also known as behavioral syndromes) in a broad range of taxa, where individuals exhibit within-individual behavioral consistency (i.e., individuals have a behavioral type, BT) and different individuals differ consistently in BT across a range of situations or contexts. Most of the study on animal personalities has focused on individual variation in boldness, aggressiveness, activity, or exploratory tendency, with a growing interest in sociability. Because behavioral syndromes clearly influence fitness, often in complex, context-dependent ways, they can have important ecological and evolutionary implications. Perhaps most intriguingly, some studies show that having a BT can be associated with limited plasticity and suboptimal behavior. Here, I report on three frontline areas of interest in the study of behavioral syndromes. First, I review literature on proximate and ultimate approaches to understanding patterns about the existence, stability and structure of animal personalities. I present a new conceptual framework that integrates proximate and ultimate approaches, emphasizing the importance of positive feedback loops between proximate mechanisms and adaptive behavior. Second, I discuss emerging ideas on the social ecology of behavioral syndromes – on how social interactions and social situations influence the expression of BTs, and in turn, how the mix of BTs in a social group influences social dynamics. Finally, I discuss the ecological implications of behavioral syndromes – how individual or species’ BTs affect ecological interactions, how variation in BTs or BTs of particular keystone individuals affect population/community level patterns, and most interestingly, how behavioral correlations affect population/community level phenomena. A particularly intriguing example of the latter involves the importance of BT-dependent dispersal in ecological invasions. I conclude with a list of suggestions on exciting areas for future study.