Preface: Plasticity and Diversity in Behavior and Brain Function – Important Raw Material for Natural Selection?

Abstract

There is no doubt that interest in both ultimate and proximate causes of individual variation is increasing. In a recent paper, Wolf et al. [2007] demonstrate how lifehistory theory can be used to explain the continued presence of divergent phenotypes, or personalities. Regarding the question of limited plasticity, an impetus of the 2006 Karger Workshop was to point out that behavioral states have physiological correlates, and physiology may control behavior as much as behavior controls physiology. In some cases, neurobiological mechanisms that cause variation in behavior are quite plastic and modified by experience, in other cases certain traits appear to be life-long characteristics. This symposium’s keynote lecturer, Jaap Koolhaas, and co-authors [Koolhaas et al., 1999] were among the first to point out how genetic and epigenetic factors combine to generate a relatively stable trait characteristic that confers differential adaptation to environmental conditions such as population density, social stability and food availability. The aim of the symposium was to synthesize current knowledge of proximate and ultimate mechanisms involved in maintaining individual variation in behavior, focusing on the relationship between brain structural plasticity, cognitive processes, and behavioral outcome in comparative and mammalian models. During the symposium, we were shown several examples of both heritable and apparently consistent trait associations [e.g. Veenema and Neumann, 2007; Schjolden and Winberg, 2007], and rapidly modifiable responses [Burmeister, The concept that humans show consistent individual differences in personality is familiar to us all, and most people would agree with the definition suggested by Pervin and John [1997], who stated that personality is: ‘Those characteristics of individuals that describe and account for consistent patterns of feeling, thinking, and behaving’. In other words: If what a man does in a certain situation predicts his behavior the next time he is in a similar situation, or even his behavior in other contexts, he has a personality. Behavioral correlation across situations, i.e. the analogue of personality, have recently been documented by ethologists and behavioral ecologists in a broad range of species, including several mammals, birds, lizards, amphibians, fish, mollusks, and arthropods [see e.g. Gosling, 2001; Bell and Stamps, 2004; Sinn and Moltscha niwskyj, 2005]. Referring to the fact that suites of correlated traits are often described as syndromes, Sih et al. [2004] coined the term behavioral syndromes, and pointed out that this phenomenon can have important ecological and evolutionary implications. For instance, the notion of behavioral syndromes implies limited behavioral plasticity. Limited plasticity, in turn, may pose problem in rapidly changing environments, such as humandisturbed habitats [Sol and Lefebvre, 2000; Sol et al., 2002]. Another question is how variation is maintained in a population. In other words, why does a population not simply drift towards a homogeneous group of the most successful phenotypes? Published online: September 18, 2007