Associations and basis of personality, life-history and social interactions

During recent years, studies of animal personalities and behavioural syndromes have received a wide attention among behavioural ecologists. One of the key aims of the field has been to understand the emergence and maintenance of animal personalities in independent populations. Animal personality is defined as consistent betweenindividual differences in behaviour across time and / or across contexts. Association between two or more behaviours is defined as behavioural syndrome. Hypothesized integration between animal personality and life-history has created a need to understand the evolutionary aspects of the potential integration structures. For this thesis, I studied 1) whether the key behavioural traits (i.e. boldness and aggression) can be considered as personality traits in our study populations and if behaviours integrate into behavioural syndromes in our model organism Western stutter-trilling cricket, Gryllus integer, 2) whether certain life-history traits (cellular immune defence, maturation time and body mass) would be associated with personality. I also examined 3) the nature of these associations (i.e. phenotypic or genetic) and 4) if social environment has an impact on personality or behavioural syndromes. Thus, I studied both ecological and evolutionary aspects of these associations. Finally, I build 5) a conceptual framework to understand the evolutionary potential of behavioural plasticity, emergence of personalities and coexistence of different behavioural types. My results indicate that there are stable between-individual differences in boldness in our study population and therefore, animal personalities. Boldness and immunity were associated phenotypically, but not genetically. Moreover, boldness and lifehistory were not associated. Maturation time, body mass and encapsulation were all associated phenotypically. These phenotypic correlations were partly underpinned by relatively tight genetic correlations. Thus, it is possible that these tight, genetic associations between the traits may limit the evolutionary potential of individual traits. Moreover, social interactions induced by variations in population density during ontogeny can generate a behavioural syndrome between two distinct behaviours (aggression and boldness). Repetitive aggressive encounters do not affect the individual level of boldness, but dominant individuals are consistently bolder compared to subordinant. Environmental variation may affect the emergence of consistency in behaviour so that animal personalities may be most likely present in environments with little variation or with high amount of variation. Universal Decimal Classification: 591.51, 591.55, 591.57