UCLA

Animal personality, or consistent individual behavior, is wide spread across taxa, and is now being linked to ecology and evolutionary dynamics. Despite interest in the ecological and evolutionary consequences of personality, few studies have used a Tinbergian approach to understanding the causes and maintenance of personality. Furthermore, there is a large amount of variation within personality traits, and as evolutionary biologists, we are keenly interested in how variation is caused, develops, and is maintained within a population. My dissertation use Tinbergian principles to try and explain personality using yellow-bellied marmots (Marmota flaviventris) as a study system. First, I explore the methodology that describes personality traits by testing whether unacquainted raters could reliably assess subjects using subjective ratings. I found that raters could reliably measure subjects, and some of these measures were valid when compared to behavioral codings. I then focus on the development of personality and found that docility and boldness do not follow the same ontogenetic path. These traits become repeatable at different life stages, and this may reflect differences in stage-specific life history strategies. I also found that boldness and docility do not form a behavioral syndrome, and that this is most likely due to the differences in development. My next chapter focuses on the causes and maintenance of personality. I test three major theoretical hypotheses — growth-mortality tradeoffs, residual reproductive value, and state-dependent safety — and found no evidence for any. I did, however, find that different environmental variables differentially influence the same personality traits across contexts suggesting that selection can influence the same personality trait through different variables depending on the context. Finally, I explore the quantitative genetics of personality. To fully understand the evolution of personality, we need to know the heritability and correlations underlying these traits. I found low heritability in most personality traits with some correlations. This dissertation shows, that in marmots, personality is heavily influenced by environment and that personality is linked to life history strategy.