Function of structured signalling in the black widow spider Latrodectus hesperus

Abstract

Many animals communicate using complex signals composed of multiple components. In some, multiple distinct signal components are organized into stereotyped sequences. Few studies, however, have examined how such temporal structure might arise, or how this structural complexity relates to signal function. Male black widow spiders ( Latrodectus hesperus ) intermittently transition from a ‘haphazard’ production of three distinct vibratory signal components to a temporally structured multicomponent display during courtship. In this study, we examined the function of structured signalling during courtship in L. hesperus . More specifically, we examined whether structured signalling rates is predicted by male mass and whether structured signalling rates predict male mating success. Then, we experimentally tested the consequences of removing one of the signal components (abdominal tremulation) for male mating success. Larger males had lower signalling rates, suggesting a trade-off between structured signalling and mass. Males that produced structured signals more frequently mated sooner. Impairment of abdominal tremulation did not affect copulation success, but these ‘muted’ males took significantly longer to mate. Our study demonstrates that the temporal arrangement of signal components is important for male mating success in L. hesperus . • During courtship, males may switch from haphazard displays to structured signalling. • Males that displayed structured signals more frequently (higher rates) mated sooner. • Smaller males produced structured signals more frequently than larger males. • Attenuating one of the signal components increased the latency to copulate.