Animal Personality Research Research Articles

Metamorphosis and animal personality: a neglected opportunity

Developmental perspectives represent an underutilized area of animal personality research, in spite of their obvious importance in biology. Animals that undergo metamorphosis are particularly neglected and represent a unique in situ experimental opportunity to study how personality differences are associated with physiological, morphological, or ecological traits over development.

No evidence for negative frequency-dependent feeding performance in relation to personality

An increasing number of studies report the presence of consistent individual differences in behavior and/or physiology over time and context, known as animal personality. A pivotal question in animal personality research concerns the mechanism(s) responsible for its evolution and maintenance. Negative frequency–dependent selection is considered to be one of these important mechanisms, although evidence for this is largely absent. Here, we studied whether the feeding performance of barnacle geese was negative frequency-dependent in a producer–scrounger game. We studied the feeding time of one bold or one shy individual in groups consisting of only bold or shy companions to study if the rare type in the group performs best. A previous study with this species showed that scrounging increased with shyness. Hence, we expected shy individuals to do better in the presence of bold companions due to the increased scrounging opportunity and bold individuals to do better in the presence of shy companions as there were ample opportunities to produce food. We found no evidence for negative frequency–dependent feeding success; rather, we found that, independent of their boldness score, all individuals enjoyed higher feeding success when foraging with bold than with shy companions. The higher foraging success of individuals foraging with bold companions is explained by a higher joining proportion in the presence of bold companions. Our results provide no evidence for negative frequency– dependent feeding success in barnacle geese but indicate that both bold and shy individuals can increase their foraging returns

Evolutionary genomics of animal personality

Research on animal personality can be approached from both a phenotypic and a genetic perspective. While using a phenotypic approach one can measure present selection on personality traits and their combinations. However, this approach cannot reconstruct the historical trajectory that was taken by evolution. Therefore, it is essential for our understanding of the causes and consequences of personality diversity to link phenotypic variation in personality traits with polymorphisms in genomic regions that code for this trait variation. Identifying genes or genome regions that underlie personality traits will open exciting possibilities to study natural selection at the molecular level, gene-gene and gene-environment interactions, pleiotropic effects and how gene expression shapes personality phenotypes. In this paper, we will discuss how genome information revealed by already established approaches and some more recent techniques such as high-throughput sequencing of genomic regions in a large number of individuals can be used to infer micro-evolutionary processes, historical selection and finally the maintenance of personality trait variation. We will do this by reviewing recent advances in molecular genetics of animal personality, but will also use advanced human personality studies as case studies of how molecular information may be used in animal personality research in the near future.

Rating vs. coding in animal personality research

Animal personality research has become increasingly popular over the past few decades. The two main methods used to examine individual differences in animals are rating and coding. The rating method involves human scoring of an animal's behavioral tendencies along various behavioral dimensions, such ratings are typically based on the human rater's experience with the animal. The coding method also requires humans to score an animal's behavior, but differs in that the scoring is based on the animal's immediate behavior in a specific context. This brief report describes the use of both the rating and coding methods to examine personality within a group of 10 Garnett's bushbabies (Otolemur garnettii). The results indicated that individual personalities do exist in bushbabies, but also suggested that the rating method is heavily influenced by the rater's experience with an animal. Consequently, it is important that the nature of the rater's interactions with the target animals be considered when using the rating method to assess animal personality.

Energy metabolism and animal personality

In this paper we show how animal personality could explain some of the large inter‐individual variation in resting metabolic rate (MR) and explore methodological and functional linkages between personality and energetics. Personality will introduce variability in resting MR measures because individuals consistently differ in their stress response, exploration or activity levels, all of which influence MR measurements made with respirometry and the doubly‐labelled water technique. Physiologists try to exclude these behavioural influences from resting MR measurements, but animal personality research indicates that these attempts are unlikely to be successful. For example, because reactive animals “freeze” when submitted to a stress, their MR could be classified as “resting” because of immobility when in fact they are highly stressed with an elevated MR. More importantly, recent research demonstrating that behavioural responses to novel and highly artificial stimuli are correlated with both behaviour and fitness under more natural circumstances calls into question the wisdom of excluding these behavioural influences on MR measurements. The reason that intra‐specific variation in resting MR are so weakly correlated with daily energy expenditure (DEE) and fitness, may be that the latter two measures fully incorporate personality while the former partially excludes its influence. Because activity, exploration, boldness and aggressiveness are energetically costly, personality and metabolism should be correlated and physiological constraints may underlie behavioural syndromes. We show how physiological ecologists can better examine behavioural linkages between personality and metabolism, as required to better understand the physiological correlates of personality and the evolutionary consequences of metabolic variability.

Personality in the behaviour of great apes: temporal stability, cross-situational consistency and coherence in response

Using a multidisciplinary approach, the present study complements ethological behaviour measurements with basic theoretical concepts, methods and approaches of the personality psychological trait paradigm. Its adoptability and usefulness for animal studies are tested exemplarily on a sample of 20 zoo-housed great apes (five of each of the following species): bonobos, Pan paniscus; chimpanzees, Pan troglodytes verus; gorillas, Gorilla gorilla gorilla; and orang-utans, Pongo pygmaeus abelii. Data on 76 single trait-relevant behaviours were recorded in a series of 14 laboratory-based situations and in two different group situations. Data collection was repeated completely after a break of 2 weeks within a 50-day period. All behaviour records were sufficiently reliable. Individual- and variable-oriented analyses showed high/substantial temporal stability on different levels of aggregation. Distinctive and stable individual situational and response profiles clarified the importance of situations and of multiple trait-relevant behaviours. The present study calls for a closer collaboration between behavioural biologists and personality psychologists to tap the full potential of animal personality research.

Understanding Personality by Understanding Companion Dogs

ABSTRACTThe study of personality is well established in human psychology, with trait theory being perhaps the most widely accepted of the personality theories. Animal personality research has utilized trait theory to identify personality factors in a wide variety of animal species. However, it has been somewhat hampered by attempting to apply human personality dimensions to animals rather than investigating the depth and breadth of personality in individual animal species. Research into animal personality offers human personality researchers the chance to explore the evolution and development of human personality. This can best be done by exploring the expression of personality in other species without restriction to human personality models. This paper suggests that the dog, Canis familiaris, is a suitable species to begin with because of its unique place in human society, its history and familiarity with humans, and its genetic plasticity. A potential structure of canine personality is proposed.

Contribution of genetics to the study of animal personalities: a review of case studies

Summary The need for evolutionary studies on quantitative traits that integrate genetics is increasing. Studies on consistent individual differences in behavioural traits provide a good opportunity to do controlled experiments on the genetic mechanisms underlying the variation and covariation in complex behavioural traits. In this review we will highlight the contribution of genetic studies in animal personality research. We will start with reviewing the evidence that shows how much variation in animal personality traits is genetic, and connect this to knowledge from human personality studies. We will continue by considering the nature of that variation, its generation and maintenance. Finally we will point to further possibilities for studying the genetics of animal personalities. We will underline the importance of integrating both proximate and ultimate approaches when studying the evolution of animal personalities.