Behavioral repeatability of flour beetles before and after metamorphosis and throughout aging

摘要

Behavioral repeatability is an important trait relevant to personality research and to behavioral ecology in general. We examined here the behavioral repeatability of two activity-related traits: movement and edge preference (proportion of time spent next to the test arena edge). We used the red flour beetle as our test species in order to determine whether repeatability changes throughout metamorphosis and aging and whether there are inter-sexual differences. Young adults moved more than larvae, but movement activity generally declined with age. Behavioral repeatability was high between two successive measurements for larvae and young adults, but did not persist through metamorphosis. These findings support most of the previous studies on insects and probably reflect the occurrence of phenotypic reorganization during metamorphosis. Neither of our predictions of an increase in behavioral repeatability throughout aging and of a higher repeatability of young adults than larvae held true, as repeatability levels estimates remained similar across ontogeny and aging. Similar to other studies on repeatability, estimates declined with the time interval between two pairs of measurements, suggesting an episodic physiological basis for the documented behaviors. Finally, we detected several inter-sexual differences. Females were more active than males and expressed a shallower decline in movement with aging. Female movement activity was also more repeatable, but female edge preference was less repeatable than that of males. We reason that such differences in repeatability may be driven by sex-specific selection pressures on behavioral tendencies.