Does the environmental context of a signalling male influence his attractiveness?

Abstract

How sexually selected male signals and female sensory systems have evolved so that females can continue to detect and discriminate between potential mates in the face of environmental noise and changes in signaller density has been well studied for acoustic signals. Far less is known about visual signals. We examined the influence of the local signalling environment on male signal attractiveness in the fiddler crab Uca mjoebergi. We used custom-built robotic crabs in two-stimulus mate choice experiments. Females were presented with two identical signals produced in two different signalling environments (simple and complex). The conspicuousness/attractiveness of male claw waving was unaffected by the local environment (physical or social). Male U. mjoebergi appear to produce a signal that is highly conspicuous across a wide range of naturally occurring signalling environments and females seem to have a sensory system that is capable of coping with high levels of environmental noise.