The establishment of bachelor gorilla groups in captivity, along with the continued success of the captive breeding programme provides an opportunity for research on social interactions in two differing circumstances. This thesis focuses on male – male social interactions. Emphasis is placed on dominance and affiliative behaviours and gives indications of the level of behavioural flexibility within both breeder and bachelor gorilla groups. Evaluation of behavioural diversity, to validate the use of multi-institutional research, confirms that behavioural phenomena, such as the effect of age class, are not masked by the potential confound of differing husbandry practices and enclosure design between institutions. It was found that males in bachelor groups express significantly lower frequencies of both dominance and aggressive behaviours than males in breeder groups. A Relationship Quality Index (RQI, based on the ration of dominance to affiliative behaviours) was developed and again bachelor males exhibited a significantly lower RQI, indicating that bachelor males express a greater frequency of dominance behaviours than affiliative behaviours. This may have a direct impact on the social development of young males, and potentially their social competence in later life, a significant finding for the management of gorillas in captivity. In addition, it can be suggested that affiliative behaviours, which may work to repair damage to social bonds, may not be performed to the same extent in bachelor groups, suggesting that the ‘value’ of social bonds within a bachelor group may be reduced.

付記する学位プログラム名: 霊長類学・ワイルドライフサイエンス・リーディング大学院 / 京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第22878号 / 理博第4644号 / 新制||理||1668(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)准教授 足立 幾磨, 准教授 Michael Alan Huffman, 教授 高田 昌彦 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

Personality is one of the most broad and complex areas in psychology. This has led to many researchers attempting to reduce this complexity by focusing solely on how habitual personality differs between each individual (inter-individual differences). This is important to study, but it has been focused on so heavily that research into how each individual personality varies within the person (intra-individual differences) has been neglected in comparison. Recent research has started to examine intra-individual variation in personality more thoroughly. One research aim of this programme was to establish the nature of several different types of within person variability including inter-item variation (variation within the test responses for a personality trait), and cross-contextual variation in personality (variation according to context), to see whether these types of variability are associated with psychological outcomes. Three research questions were examined to this end: 1) What is the extent of meaningful variability in personality trait test responding? 2) What are the predictors of intra-individual variability in personality? 3) What is the relative importance of the person and situational factors in personality variability? The first question was developed to try and determine whether the individual can display meaningful inter-item variation in ratings of specific behaviours within personality trait measures. Trait questionnaires are usually only analysed at the between subject level, and within subject variation in inter-item ratings have not been extensively examined in relation to meaningful psychological outcomes. The second and third questions were developed to look into the nature of cross-contextual personality, and establish whether within person personality differences are influenced more strongly by the person or situation. The studies conducted towards answering these questions demonstrated a person-based capacity to display intra-individual variability. A second aim of the research programme was to see whether the capacity to display these types of variability can be utilised in behaviour change. The fourth research question was developed to try and understand how a person can display intra-individual variability, yet still be resistant to changing negative habits: 4) How do the different aspects in personality variability help explain why some people are resistant to change, especially with regard to behaviours that are bad for them? This question was answered by theoretically discussing the findings from the three previous studies which proposed that positive or problematic behaviour could be interpreted with a simple path to understand the process of behavioural action: The individual receives feedback from a behaviour response which either validates or invalidates their action in the situation context (does or does not receive a desired outcome). Reinforcement of the behaviour happens if it is validated by positive feedback. Alternately reconstruction of the situation happens if the behaviour is invalidated. This allows for two types of intra-individual variability. One is flexibility in behaviour responses to different situations under the individual’s control. The other is change according to the situation, where the behaviour is invalidated and an alternative is attempted. A problematic behaviour may have benefit in stopping something invalidating, but if repeated it may become a habit needed for psychological functioning. As part of the second research aim a behaviour change strategy was developed and piloted to try and bring the individual closer to their construct of the ideal self. Instructions were provided for the individual to experiment with that differed from their disposition. The programmes had varied degrees of success depending on the participant. The implications for personality research and behaviour change are discussed.

No description available.

Despite the potential benefits of modifying behaviour according to changing ecological conditions, many populations comprise individuals that differ consistently in behaviour across situations, contexts and points in time (i.e. individuals show personality). If personalities are adaptive, the balance between consistency and flexibility of behavioural traits should reflect the ability of individuals to detect and respond to changing conditions in an appropriate and timely manner and, thus, depend upon the pace and predictability of changing conditions. We investigated the balance between individual consistency and flexibility in the subsocial spider Anelosimus studiosus by assaying boldness across the diel cycle and correlating these data with patterns of prey and threat abundance in the natural habitat. We found significant diel flexibility in boldness correlating with drastic and predictable changes in prey availability. Moreover, the strength of within-individual flexibility in boldness was comparable to the strength of rank-order consistency among individuals. We also found evidence that mean boldness level and among-individual variation in boldness are correlated with reproductive status. These data emphasize the interplay between behavioural consistency and flexibility and suggest that temporal characteristics of ecological conditions may be vital in assessing the strength, stability and adaptive value of animal personalities.

Cumulative culture is rare, if not altogether absent in non-human species. At the foundation of cumulative learning is the ability to flexibly modify, relinquish or build upon prior behaviours to make them more productive or efficient. Within the primate literature, a failure to optimise solutions in this way is often proposed to derive from low-fidelity copying of witnessed behaviours, sub-optimal social learning heuristics, or a lack of relevant socio-cognitive adaptations. However, humans can also be markedly inflexible in their behaviours, perseverating with, or becoming fixated on outdated or inappropriate responses. Humans show differential patterns of flexibility as a function of cognitive load, exhibiting difficulties with inhibiting suboptimal behaviours when there are high demands on working memory. Here I present a series of studies on captive chimpanzees which show that not only is inhibitory control compromised in chimpanzees, but indicate ape behavioural conservatism may be underlain by similar constraints as in humans; chimpanzees show relatively little conservatism when behavioural optimisation involves the inhibition of a well-established but simple solution, or the addition of a simple modification to a well-established but complex solution. In contrast, when behavioural optimisation involves the inhibition of a well-established but complex solution, and especially when the alternative solution is also complex, chimpanzees show evidence of behavioural conservatism. I propose that conservatism is linked to behavioural complexity, potentially mediated by cognitive resource availability, and may be an important factor in the evolution of cumulative culture.

In an effort to better understand primate behavioural flexibility and responses to low-biomass habitats, behavioural patterns of ring-tailed lemurs (Lemur catta) living in a xerophytic spiny forest habitat in southern Madagascar were examined. Behavioural data were collected over two months on two separate groups living in two distinctly different habitats: a sub-desert spiny forest and a riverine gallery forest. Data on the following behavioural categories integral to primate sociality were collected: time allocation, anti-predator vigilance, predator sensitive foraging, feeding competition, and affiliative behaviour. L. catta living in the spiny forest habitat differed significantly in many behavioural patterns when compared to L. catta living in the gallery forest. I suggest that the ability to successfully alter behavioural strategies to varying ecological conditions allows ring-tailed lemurs to occupy low biomass habitats which are uninhabitable to nearly all other primate species in Madagascar. Lemur catta evolution, behavioural flexibility, and conservation will be discussed.

In an effort to better understand primate behavioural flexibility and responses to low-biomass habitats, behavioural patterns of ring-tailed lemurs (Lemur catta) living in a xerophytic spiny forest habitat in southern Madagascar were examined. Behavioural data were collected over two months on two separate groups living in two distinctly different habitats: a sub-desert spiny forest and a riverine gallery forest. Data on the following behavioural categories integral to primate sociality were collected: time allocation, anti-predator vigilance, predator sensitive foraging, feeding competition, and affiliative behaviour. L. catta living in the spiny forest habitat differed significantly in many behavioural patterns when compared to L. catta living in the gallery forest. I suggest that the ability to successfully alter behavioural strategies to varying ecological conditions allows ring-tailed lemurs to occupy low biomass habitats which are uninhabitable to nearly all other primate species in Madagascar. Lemur catta evolution, behavioural flexibility, and conservation will be discussed.

Faire un choix n’est pas juste un évènement spontané. La recherche d’une ressource alimentaire, par exemple, implique un investissement temporel et est donc en conflit avec d’autres activités essentielles telles que la vigilance pour les prédateurs. Ainsi être sélectif augmente le risque de se faire attaquer par un prédateur. Par ailleurs, être sélectif implique aussi de rejeter beaucoup de potentielles options avant de finalement en accepter une et donc accepter une perte non négligeable d’opportunités en présence de potentiels compétiteurs. Pour ces raisons, une réduction du niveau de sélectivité est attendue chez un individu exposé à une situation de forte compétition ou à un fort risque de prédation. Les carabes évoluent au sein de communautés composées, pour la plupart, d’un nombre important de potentiels compétiteurs et prédateurs. Les connaissances actuelles en écologie comportementale et en écologie prévoient que le comportement d’approvisionnement alimentaire des coléoptères carabiques devrait varier en fonction des niveaux de risques de compétition et de prédation qu’ils rencontrent et donc de la composition des communautés dans lesquelles ils se trouvent. Dans cette thèse, nous avons mesuré les changements de sélectivité alimentaire de deux espèces de carabes en présence de signaux de prédateurs ou de compétiteurs. A l’aide d’expériences de laboratoire effectuées à différentes échelles spatio-temporelle, nous avons réussi à montrer que la sélectivité alimentaire d’un carabe granivore Harpalus affinis peut varier en fonction du contexte dans lequel il cherche sa nourriture et être diminuée en présence de prédateurs. Par ailleurs le sexe des individus, l’espèce de graine qui leur est proposée et l’intensité du risque auquel ils sont confrontés semblent aussi avoir un effet sur la variation de sélectivité des individus. Aucun lien n’a cependant été trouvé entre le statut immunitaire ou la personnalité des individus et leur niveau de sélectivité alimentaire. Testé dans des conditions similaires, le carabe omnivore Poecilus cupreus, quant à lui, ne fait pas varier sa sélectivité pour les ressources testées. S’ils sont extrapolables ces résultats pourraient servir à expliquer la grande variabilité des taux de prédation de graines au champ par les carabes rapportés dans les différentes études. Ces résultats pourraient permettre aussi d’expliquer la difficulté d’extrapolation existante entre les taux de prédation de graines mesurés en laboratoire et les résultats obtenus au champ. Globalement, cette thèse confirme qu’une meilleure compréhension du processus de prise de décision chez les carabes est essentielle pour évaluer leur efficacité en tant que potentiels auxiliaires de cultures. / Making a choice requires, implicitly, an investment of time in one behaviour at the expense of an investment in another. Being choosy would increase the risk of losing many food item opportunities to competitors, and is directly in conflict with other essential tasks such as predator avoidance. Individuals are thus expected to adjust their level of choosiness in response to the competition and predation context. The available behavioural ecological theory and the empirical ecology of carabids would suggest that competition and predation interference induces changes in the foraging behaviour of carabid individuals. Carabids typically operate within communities in which competition and predatory interference interactions occur and are ever present; there are high levels of intraguild interference. A better understanding of how risks of these two interference interactions modify individual decision making for prey would therefore help to improve the biocontrol of weeds by communities of carabids. This thesis focused on how changes in level of choosiness occur when individual carabids forage under intraguild interference. Using laboratory experiments, done at different spatio-temporal scales, we demonstrate that the decision-making processes of foraging carabids might differ between contexts, between species and between individuals. Our focal species, the granivore Harpalus affinis, was found to reduce its level of choosiness while foraging under intraguild interference. In doing so H. affinis individuals increased their overall rate of seed acceptance. This change in choosiness was dependant on the intensity of the risk, the seed species offered in test and the sex of individuals. We found no link between individual levels of choosiness and either immunity or personality traits. When tested under similar conditions, individuals of the omnivorous carabid Poecilus cupreus did not change their level of choosiness for seeds. These findings would help explain the high variability in seed predation rates observed between studies conducted in-field, and the differences observed between laboratory studies and fields measurements in carabids. Globally, this thesis has confirmed that a deeper understanding of the decision making process of carabids seed-eating species is requires to evaluate their choice of prey and assess their relevance as biological control agents in the wild.

<p>Diss. (sammanfattning) Umeå : Umeå universitet, 1995, härtill 6 uppsatser.</p> / digitalisering@umu