Meeting Abstract

61.1  Wednesday, Jan. 6  Costs and benefits of unreliable signalling in males of the two-toned fiddler crab (Uca vomeris). BYWATER, C.L.*; WILSON, R.S.; The University of Queensland; The University of Queensland c.bywater@uq.edu.au

Many species possess exaggerated secondary sexual structures which are used for signalling during mate attraction and pre-fight assessment. Signals are either reliable, where information about underlying quality is accurately conveyed to the receiver or unreliable, where signallers send inaccurate information. Theoretical models predict that reliable signals should be more prevalent in nature, as a purely unreliable system would collapse due to the redundancy of the signal. However, documented cases of naturally occurring unreliable signals are becoming more frequent with unreliable signallers present in much greater numbers than predicted. Understanding the costs and benefits of unreliable signals of strength are critical to theoretical models, but these have not been fully established, nor has it been ascertained whether unreliability is a condition-dependant strategy. The fiddler crab is an ideal system for studying unreliability as males possess a greatly enlarged claw used for displaying during mate attraction and male-male combat. We first determined the relationship between claw size and strength for 120 individual male two-toned fiddler crabs (Uca vomeris) to identify reliable and unreliable signallers. We then assessed the competitive ability of each individual male and their attractiveness to females in the field to determine the social benefits and costs of unreliable signals. Finally, we tested each individual’s sprint speed and endurance before and after major-claw removal to determine the relationship between an individual’s condition and their signal reliability. We will discuss the costs and benefits of unreliable signals for male U. vomeris and their implications for signalling theory.