Meeting Abstract

60.2  Thursday, Jan. 6  The physiological basis of dishonest signals of strength in males of the fiddler crab Uca vomeris. BYWATER, CL*; WHITE, C; WILSON, RS; The University of Queensland; The University of Queensland; The University of Queensland c.bywater@uq.edu.au

Unreliable signals of weapon strength (signals that are poor indicators of strength) are considered problematic for signalling theory and reliable signals are predicted to be the dominant form of signalling among conspecifics in nature. Despite theoretical assertions, the males of several species of crustaceans routinely utilise dishonest signals of strength during agonistic interactions. In this study, we examined the physiological basis of dishonest signals of strength in males of the fiddler cab Uca vomeris. Male fiddler crabs possess one enlarged and brightly coloured claw that is used both as a weapon during disputes with other males and to attract females during courtship. The males of many fiddler crabs can regrow a new claw after losing it during disputes, but this new claw has less mass, is less effective as a weapon and costs less to signal to opponents. Despite the weaker nature of these regenerated claws, they can operate as effective dishonest signals of strength and can deter potential opponents before they fight. We tested the claw strength and metabolic rate of claw tissue of original- and regenerated-claw U. vomeris to determine the consequences of possessing a putative dishonest signal of strength for this species. In addition, we examined the biochemical basis of muscle strength for both types of fiddler crab claw to discover whether individuals with regenerated claws regrow less effective muscle. We will discuss the importance of our results for understanding the evolution of signals of strength.