Social behavior and activity are decoupled in larval and adult fruit flies

The growing body of literature on social behavior in fruit flies opens up exciting opportunities for addressing an unresolved issue involving the degree of correlation between behavioral traits in larvae and adults. Although the prevailing adaptive decoupling hypothesis states that metamorphosis is associated with the disruption of genetic correlations between juvenile and adult traits, 2 alternative hypotheses are that, sometimes, a positive correlation may be adaptive, and that, often, the underlying genetic architecture will prevent perfect decoupling. We used lines of the Drosophila Genetic Reference Panel to quantify the degree of sociality in larval and adult fruit flies and then examined the correlation between the life stages. To verify that our social behavior scores did not merely reflect variation in activity levels, we also quantified larval and adult activity. Although we found significant variation in social behavior and activity among larvae and adults, both traits were decoupled between larvae and adults. Social behavior and activity were not positively correlated within each life stage either. Although our results agree with the adaptive decoupling hypothesis, both ultimate and proximate considerations suggest that, generally, we should expect the degree of decoupling to vary between species and traits.