打鬥勝敗經驗效應展現之差異性、一致性與母體效應

A large amount of studies have shown that individuals tend to behave consistently but differently over time and across contexts. For instance, some individuals tend to exhibit higher levels of aggression in different contexts (e.g., foraging, mating) than the other individuals. State-dependent personality models suggest that an individual’s state (morphology, physiology, environment, etc.) affects the balance between the costs and benefits of different behaviors and prompts it to behave consistently in certain ways. In addition to an individual’s state, maternal experience is also important in shaping an individual’s behavioral tendency and responsiveness. Material influences could help the offspring to better cope with the environment. Individuals that have won or lost a fight recently are more likely to win and lose again, respectively (winner/loser effect). Different individuals may differ in their propensity to modify behavior after winning/losing experience. Despite the prevalence of winner and loser effects in the animal kingdom, differences and consistency in individual response to winning or losing experiences have not been investigated. Using mangrove killifish, Kryptolebias marmoratus, this project investigated (Study 1) whether different individuals of the fish show different but consistent responsiveness to winning or losing experiences, and if so, whether the responsiveness/consistency is associated with the individual’s behavioral tendency and intrinsic state, and (Study 2) the importance of maternal experience to offspring’s behavioral tendency and responsiveness as well as the importance of maternal physiology and behavior in predicting the offspring’s physiology and behavior. The results of Study 1 showed that (1) the attack rate and the levels of testosterone and cortisol are highly consistent in the fish, (2) the consistency in the attack rate was higher than the consistency in the hormone levels, indicating that the levels of these hormones are not the physiological mechanisms that promoted the consistency in the attack rates, and (3) individuals of the fish did not appear to respond consistently to winning or losing experiences. The results of Study 2 showed that (1) parents’ contest experiences significantly affected offspring’s aggressiveness and responses to contest experiences: the offspring of parents with losing experiences attacked their mirror images at higher rates and showed greater loser effects, (2) parent fish that received losing experiences had lower consistency in their aggressiveness, (3) parent’s and offspring’s levels of aggressiveness and hormones were not positive correlated, (4) linage did not have consistent influences on parent’s and offspring’s levels of aggressiveness or hormones. Overall, these results showed the fish’s aggressiveness to be consistent over time, but the physiological mechanisms important to the consistency remain unclear. Although parents' contest experiences had important influences on the offspring’s behaviors, the heritability of the fish's behavior and hormone levels might not be very high.