Abstract
Theoretical analyses indicate that aggressive signals should positively correlate with the signallers' willingness and abilities to fight. Few experimental studies, however, have tested this prediction. In two experiments employing distinct, ecologically realistic protocols, we quantified the association between aggressive signals and fighting in fruit fly genotypes and found high positive genetic correlations between threat and fighting (r(G) = 0.80 and 0.74). Our results add to the growing body of experimental work indicating that aggressive signals have relatively high informational value.