Female Wolf Spider, Schizocosa Avida, Vibration Receptor Responses To Male Courtship

Spiders are model systems for exploring proximate and ultimate questions about the evolution of vibratory signals. However, little is known of the sensory response characteristics of receivers, with one exception in Cupiennius spp. Spiders have vibration receptor organs called metatarsal organs on their legs. The organs contain aggregations of slit sensilla that respond to cuticular strain caused by substrate vibrations. Two neurons innervate each sensillum. How distal and proximal slit sensilla responded to male vibratory courtship components were shown. Neurons in isolated female legs were recorded extracellularly as a male courted nearby. Across 5 females, 9 slits were recorded in total. In one preparation, both distal and proximal slit responses to male vibratory courtship were captured. Altogether, distal slit responses captured primarily vibrations produced by male leg taps while proximal slit responses captured vibrations produced by male leg taps and drumming of pedipalps (male appendages used for sperm transfer). In addition, leg taps of variable amplitude elicited similar neural responses in all recorded slits. Compared to preparations in which female leg tarsi were immobilized, treatment preparations of movable female tarsi provided reliable neural responses to male courtship. Probing sensory processing features of females allows exploration into how male signals are encoded. Such work could inform how receiver sensory systems might influence the evolution of male signals.