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Unraveling the function and evolutionary history of multimodal signaling is a difficult, yet common task of much research in animal communication. Here, I investigated multimodal signal function in the visual and seismic courtship display of the wolf spider Schizocosa stridulans and found that only the seismic courtship signal was important for mating success. First, copulation frequency was assessed in the presence/ absence of both visual and seismic courtship signals. The seismic signal was sufficient for successful copulation, whereas the visual signal was neither necessary nor sufficient, suggesting that the signals are not redundant and do not function as backups. Next, female receptivity to video courtship sequences with altered male ornamentation was assessed in the presence of a live male’s seismic signal. Female receptivity did not depend on male foreleg ornamentation. Instead, females performed receptivity displays equally to all video stimuli, demonstrating that in the presence of seismic signaling, receptivity is independent of visual signaling—indicating seismic signal dominance. Finally, female responses to isolated seismic cues from crickets and courting males suggest that seismic courtship signals carry both location and identification information. Schizocosa stridulans represents one of the few examples in which a single component likely dominates a multimodal signal.
Includes Supplemental Video of male courtship display, attached as "Related File" (below).