Environmental influences of behavior in two Gambusia species: Public information use and behavioral consistency across ecological and evolutionary time scales.

摘要

Animals must gather information about the location and quality of resources while simultaneously using information to avoid predation. Individuals may then use the information they gather about the relative state of their environment to modify behavior in ways that increase fitness (e.g. by using the presence of foraging conspecifics to locate food, or by using the behavior of wary conspecifics to identify predation risk). Information may be gathered directly by the individual (private information) or by observing others (public information). The ecological factors that influence how animals use private and public information remain central questions to behavioral ecologists. In particular, recent work suggests that individuals often consistently differ from one another across contexts in behavioral traits and that these `personality' differences may influence how they use information. In turn, differences in information about the environment may contribute to individual variation in behavior. For my dissertation, I examine how differences in predation risk affect how two species of mosquitofish (Gambusia affinis and G hubbsi) a) use private and public information, b) change consistency of behavior in response to differences in environmental context, and c) have behaviorally responded to divergence in ecological context across an evolutionary time scale. In chapter 2, I examine how the age of available environmental information and individual state (mass) alter how organisms value socially acquired information. Individuals did not value newer information over older information, but larger individuals were more likely to change foraging behavior after gaining public information about the location of food. In chapter 3, I found that high predation risk results in greater use of public information, even when the costs of acquiring private information about the environment are similar across environments. I suggest that, in high risk environments, individuals gain additional information such as the safety of food sources, by observing others. In chapter 4, I explore how inherent differences in behavior within a population (animal personalities) shape how the individuals use and gather environmental information. In contrast with my predictions, I found that individual differences in behavior only influenced learning. In chapter 5, I test how differences in predation risk influence consistency of behavior. I found that behavioral consistency (i.e. the repeatability of behavior) increased when predation risk was high, because of a combination of greater differences between individuals and lower variation within individuals. Finally, in chapter 6 I extended this finding to examine how long-term differences in ecological context shape individual variation in behavior over evolutionary time by using replicate populations of G. hubbsi that have evolved under high and low predation regimes. I did not find evidence of behavioral canalization in high risk populations, but I did find context-dependent behavioral consistency, similar to earlier work (chapter 5). Taken together, my results indicate that ecological context (specifically predation risk) influences public information use as well as behavioral consistency. Individuals behave more consistently and utilize available public information more when predation risk is high. This could have implications for both the cultural transmission of traits as well as long-term behavioral evolution.