by Shira | Mar 14, 2013 |
Abstract Multimodal signals may compensate for environmental constraints on communication, as signals in different modalities vary in efficacy. We examined the influence of complex microhabitats on transmission of vibratory and visual signals of courting male Schizocosa ocreata wolf spiders (Araneae: Lycosidae) with laser Doppler vibrometry (LDV) and behavioral observations in lab and field. We measured maximum potential detection distance of visual and vibratory signals by females in laboratory mesocosms, recorded vibration signal attenuation on different substrates, and estimated transmission distances for male vibration signals in the field. We also determined effective line-of sight visual detection distances in the field with laser distance measures. Together, these data were used to estimate the potential and effective active space of multimodal signals. LDV measures show leaves are highly conductive substrates for wolf spider vibratory signals compared to others (soil, wood, rock). For both visual and vibratory modes, lab estimates of maximum potential distance for signal transmission and detection (behavior studies) exceeded estimates of effective active space (signal attenuation, “vanishing point,” and “line-of-sight” measures). Field estimates of transmission distance for signal modes overlap, such that in close range (<20 cm), vibratory signals are more likely to be detected, while farther away, visual signals are more likely to be seen. These findings thus support current hypotheses regarding how multimodal communication might extend the range of overall signal active space or compensate for environmental constraints. Uetz GW, Roberts JA, Clark DL, Gibson JS, Gordon SD. 2013. Active space of multimodal signals of wolf spiders in a complex litter environment. Behavioral Ecology & Sociobiology. 67:1471-1482...
by Shira | Mar 15, 2012 |
Sound is abundant in the environment, often creating ‘‘noise’’ that interferes with animal communication. Animals cope with acoustic interference in a variety of ways, including raising their signal volume (the Lombard effect), changing the pattern, frequency or duration of signals, or changing the time of day when signaling. Although many arthropods use substrate-borne vibration (seismic) signals, the effect of interference from (airborne) acoustic noise on their communication is not well studied. We tested the effects of 3 different types of airborne acoustic sounds on substrate-borne seismic communication and mating success of the ground-dwelling wolf spider, Schizocosa ocreata. We used band-limited white noise (0–4 kHz), predatory bird calls (northern cardinal Cardinalis cardinalis), and a cicada chorus (mixed Magicicada spp.) as interference stimuli. Spider behavior and mating success were differentially affected by each type of environmental acoustic sound. Males took longer to initiate courtship with bird calls, although white noise and cicada calls did not affect male signaling. Females oriented toward males more often with white noise but showed no change in their orientation behavior with bird or cicada calls. Finally, female receptivity and mating success were reduced with white noise and bird calls, whereas cicada calls had no effect. Our data suggest that wolf spiders using seismic vibration in communication respond differently to various types of airborne sounds, transmitted as vibrations, in their environment. This work is among the first to highlight how airborne sounds create seismic interference differentially affecting the behaviors of arthropods living in the leaf litter. Key words: behavioral plasticity, bioacoustics, bird song, cicada, communication, environment, interference, Schizocosa ocreata, sound, vibration, wolf spider. [Behav Ecol] Gordon...
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