The effects of conspecific male density on the reproductive behavior of male Schizocosa retrorsa (Banks, 1911) wolf spiders (Araneae: Lycosidae)

Abstract

In the context of competitive mate searching, males may use cues from conspecifics, such as movement cues and/or courtship signals, to locate mates. For ground-dwelling wolf spiders, substrate-borne vibratory cues may be particularly important sources of information, given the potential presence of many visual obstacles. This study explores the possible use of conspecific male cues in wolf spiders by asking: (i) Do male Schizocosa retrorsa (Banks, 1911) wolf spiders use vibratory cues from conspecific males to alter their searching or signaling behavior? (ii) Can males assess the density of conspecific males using conspecific male cues? (iii) Does the variation in conspecific male density affect the behavioral response of focal males to the conspecific cues? To answer these questions, we tested the effects of (i) the number of conspecific males and (ii) the activity of conspecific males (e.g., courtship yes/no) on a focal male's behavior. We recorded the following focal male behavior: (a) the presence/absence of courtship behavior, (b) temporal/structural signal characteristics of the multimodal courtship signaling, and (c) locomotory patterns. Our results suggest that, (i) S. retrorsa males assess their competitive environment through substrate-borne vibratory cues generated by courting or non-courting behavior of conspecific neighbors, (ii) S. retrorsa males may alter their reproductive behavior between mate searching and courtship signaling by the assessment of cues associated with conspecific male density, and (iii) the assessment and perception of density-dependent conspecific courtship signaling can be used as social information to adjust the reproductive behavior.