The consequences and underlying mechanisms of animal personality in dunnocks (Prunella modularis)

Abstract

In behavioural ecology, the research of animal personality, that is, consistent between individual differences in behaviour, has attracted a considerable amount of attention during the last two decades. While past research has mainly focused on the description of personality traits in animal populations, we still know very little about the ecological and evolutionary relevance, and the mechanisms maintaining such personality traits.

This thesis seeks out to increase our understanding of the consequences and underlying mechanisms of animal personality. I used observational data to examine the long-term stability of four behavioural traits (boldness, provisioning, activity and vigilance) in a wild population of dunnocks (Prunella modularis; Chapter 2). On the one hand, dunnocks showed moderate to high repeatability in flight-initiation distance (FID) and parental provisioning over the entire study period of three years and across different age classes (age 1 to 6 years). Repeatability estimates of males and females differed in provisioning behaviour from each other. On the other hand, dunnocks displayed low levels of repeatability for activity and vigilance.

Despite this, no behavioural syndromes were found, suggesting that selection did not favour specific combinations of the four investigated traits. I also investigated which role personality traits play in the spatial distribution of behavioural phenotypes (Chapter 3). Specifically, I tested empirically tested whether personality or habituation is responsible for the non random distribution of shy and bold individuals.

My results suggest that an individual’s personality type largely determines the habitat in which an individual settles. These findings highlight the role personality plays in shaping population structure and lending support to the theory of personality-mediated speciation.Using a molecular approach, I investigated the underlying genetic basis of animal personality (Chapter 4). By comparing a native (United Kingdom, UK) and an introduced population (New Zealand, NZ) of dunnocks, I showed that the introduced population has lower genetic diversity in two ‘personality genes’, DRD4 and SERT, than the UK population. Additionally, I found 38 significant associations between polymorphisms in DRD4 and SERT, and two repeatable behavioural traits; FID and mating status.

My results indicate that anthropogenic-caused introductions may influence the genetic diversity of ‘personality genes’, and also corroborate the genetic influence of DRD4 and SERT on personality traits. Finally, I employed meta-analyses (Chapter 5) to assess which of the two proposed physiological traits, hormone levels or metabolic rates is more likely the underlying mechanism shaping personality differences.

Results of these analyses suggested that variation in metabolic rates is one of the key drivers regulating between-individual differences in behaviour. On the other hand, hormone levels seem to be more likely to control for variation at the within-individual level. Taken together, my thesis makes an important contribution to our understanding of the ecological and evolutionary consequences and underlying mechanisms of animal personality. Further, my work highlights the importance of studying personality traits in wild populations.