Male Schizocosa wolf spiders response to predator calls on wet vs dry leaf litter

Abstract

By Emmanuel Bagirov, Biology

Advisor: George Uetz

Presentation ID: PM_ATRIUM30

Abstract: Animal signals transfer information between individuals - e.g., to initiate courtship or warn of danger. The environment can play an important role in the transmission and receiving of signals. In the multimodal communication signaling of Schizocosa ocreata wolf spiders, males use substrate-borne vibratory signals for courtship. Despite having no direct means of detecting airborne sound, these spiders also respond to bird calls indicating the presence of predators, by sensing vibrations in leaf surfaces. In order to understand how the environment can affect information indicating danger, we explored whether the moisture content of leaves affected detection of bird calls by courting male spiders. The first objective was to examine anti-predator responses of male spiders courting on wet or dry leaves to Blue Jay calls. This was achieved by having two treatment groups of male S. ocreata on wet vs. dry leaves exposed to playback of a Blue Jay call being played after one minute of courtship. The results showed significantly more frequent and longer duration anti-predator "freezing" behavior of males on dry leaves as opposed to wet leaves, suggesting that leaf moisture in an environment can affect the transmission and detection of airborne signals as vibration on leaf surfaces. The second objective was to examine transmission of airborne sounds from Blue Jays through wet vs. dry leaf environments, by comparison of vibration recordings with a laser Doppler vibrometer from the leaf surface. Results will be discussed in the context of environmental influence on vibratory signal detection.