George W. Uetz Professor Ph.D., University of Illinois Animal Behavior, Behavioral Ecology, & Arachnology

Wolf spider communication project

 Animals use multiple modes of communication (e.g., sounds, visual and/or chemical cues) to recognize members of their own species and discriminate them from others. The goal of the wolf spider communication project is to understand the role of multi-modal signaling in an invertebrate animal model (wolf spiders) and its evolution.

male S. ocreata

             Our model organism is the Brush-Legged wolf spider, Schizocosa ocreata (Hentz) (Lycosidae) and its close relatives. Wolf spiders of the genus Schizocosa are common throughout the U.S. and Canada.  Forest litter-dwelling Schizocosa spiders are among the most abundant and ecologically important invertebrate predators in deciduous forests, and are currently under study by a number of scientists, including former students Dr. Gail Stratton at the University of Mississippi, Dr. Eileen Hebets at the University of Nebraska, and Dr. Matt Persons of Susquehanna University  (be sure to see Matt’s Schizocosa home page!). 

female S. ocreata with eggsac

 Behavior serves as a pre-mating reproductive isolating mechanism among Schizocosa wolf spiders (Stratton & Uetz 1981; 1986). Male wolf spiders court females with both visual and vibratory (seismic) signals, which females use to recognize mates of their own species, and to assess mate quality. Male signals are species-specific, and different species use signals in a single sensory mode (e.g., vibration signals) or multiple sensory modes (simultaneous visual and vibration signals) (Uetz & Roberts 2002).  An important question under investigation is why some species use multiple modes when a single mode should be sufficient (?).  It may be that different signal modes convey different kinds of information, or that multiple modes allow signals to be perceived under different conditions.

Visual Signals - Male S. ocreata use a number of leg-tapping, waving and arching displays in courtship and aggressive interactions.  Conspicuous tufts of bristles on the forelegs increase the detectability of these displays.
Vibratory Signals - Male Schizocosa spp. use stridulation (friction of file-and-scraper mechanisms on the pedipalps) and percussion (tapping, cheliceral strike, body bouncing) in signaling behaviors to produce vibration signals that travel through a substrate (seismic communication).
Video Digitization and Playback - Wolf spiders perceive video images on LCD mini-televisions, and respond to them as if real. We use video playback of digitized sequences of courtship (with or without modification of appearance or behavior) as stimuli in experimental studies.  This technique allows manipulation of elements of complex moving images to test hypotheses about the evolution of communication.

         There has been a great deal of interest in fluctuating asymmetry (FA) in animals – especially in the context of mate choice – as deviations from perfect left-right symmetry may indicate developmental instability (the ability of the genome to buffer environmental stress during development).  In S. ocreata, asymmetry in tufts arising from leg loss and subsequent regeneration influences sexual selection by decreasing male fighting and mating success  (Uetz et al. 1996; Uetz & Smith 1999).

              Current research, involving colleagues Dr. Phil Taylor, Dr. Andy Roberts, and graduate students Jeremy Gibson, Jenai Milliser, Julee Johns and Anne Kahne, continues to focus on a variety of aspects of multi-modal courtship, and multi-sensory guidance of behavior in Schizocosa.  Projects include studies of exploitation of male courtship signals by eavesdropping male competitors and cue-reading predators, the influence of juvenile exposure to male courtship on adult female receptivity, and coercive mating behavior of males.  In addition, field studies using Laser Doppler Vibrometry are directed toward understanding how the complex leaf litter environment of the forest floor affects transmission of different signal modes.

             Supported by the National Science Foundation.

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 Research: 1. Wolf Spider Research | 2. Colonial Web-Building Spiders Research | 3. El Niño Influence on Colonial Web-Building Spiders. |  4. Impact of a Ecosystem Disturbance on Spider Populations and Communities