Lifetime Stability, Maternal Effects, and Fitness Outcomes of Socio-Ecological Strategies in Wild Bottlenose Dolphins
Individuals within a population differ in behavior along both social and ecological axes. These differences are proposed to be governed by niche theory at the individual level, but empirical evidence is sparse, especially over longer time scales. To understand the proximate and ultimate factors behind individual socio-ecological niches, we need to know how stable individual differences are on a lifetime scale, how these multivariate traits are structured and what transmission mechanisms can tie socio-ecological differences to fitness. In this dissertation, I leverage 32 years of data collected on wild bottlenose dolphins to explore individual differences in social and ecological behavior. Chapter 1 investigates the longevity of social ‘personality’ across the lifetime of bottlenose dolphins. Multiple measurements of social behavior (time spent alone, in large groups, average # of associates and same-sex associates) were repeatable beginning in the calf period and lasting through old age. Multivariate analysis revealed that social measurements are correlated and can be treated as a behavioral syndrome akin to the human extroversion-introversion axis. Chapter 2 explores individual ecological differences, their relationship with social traits and a subsequent socio-ecological spectrum. Home range size, habitat use preferences, and some foraging tactics were individually repeatable over decades. The correlation between individual ecological behaviors and social traits exposed a socio-ecological syndrome, with sex differences dictating tradeoffs between time-intensive foraging tactics and social behaviors. Chapter 3 addresses the sex-dependent maternal effects and potential fitness effects of individual socio-ecological strategy. Maternal strategy was a strong predictor of offspring strategy, especially for females. Males were more likely to differ from their mothers compared to females. And while most strategies were not associated with differing fitness payoffs, corroborating predictions from niche theory, females that use marine sponges as tools during foraging had a reduced mortality hazard. This dissertation provides rare empirical evidence for the existence, persistence, and transmission through maternal effects of individual socio-ecological strategies and builds a framework to consider individual socio-ecology through a sex-specific evolutionary lens.
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Social Networks and Fitness Consequences of Early Sociality in Wild Bottlenose Dolphins (Tursiops sp.) Stanton, Margaret Anne (Georgetown University, 2011)Despite recent investigations into the relationship between adult social bonds and fitness in socially complex species, remarkably little attention has focused on the consequences of early sociality. For this dissertation ...