Male courtship signal modality and female mate preference in the wolf spider Schizocosa ocreata: results of digital multimodal playback studies (original) (raw)
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Animal Behaviour, 2009
Lycosidae mate choice multimodal communication Schizocosa ocreata Schizocosa rovneri seismic signal vibration signal visual signal wolf spider Male wolf spiders (Lycosidae) in the genus Schizocosa vary in use of seismic and visual components of courtship display, ranging from unimodal (seismic only) to multimodal (seismic and visual). Studies show that variation in individual modes influences female receptivity, but responses to isolated signals may not be equivalent. To examine redundancy and interaction between modes, we compared female responses to isolated and combined courtship signals from males of two sympatric sibling species that differ in use of visual and seismic modes, S. ocreata and S. rovneri. Females of both species detected multimodal stimuli faster than visual or seismic cues alone, but they differed in responses to cues once they oriented. Female S. ocreata approached males performing isolated visual and seismic cues with equal frequency, but approached males performing multimodal cues more often. A greater proportion of female S. ocreata responded more receptively to multimodal cues than to seismic or visual cues alone, and showed higher rates of receptivity displays with multimodal cues. In contrast, female S. rovneri showed no differences in approaches, but responded more often and with higher display rates to seismic cues alone or multimodal cues, but not visual cues. These results suggest multimodal signalling increases detection of males by females, but that use of signal modes varies between even closely related sibling species. For S. rovneri, male signals in different modes are nonredundant, with seismic cues dominant over visual cues when presented alone or in multimodal signals. In contrast, for S. ocreata, male signals in different modes are redundant (eliciting the same responses from females with similar frequency), while the greatly increased responsiveness to multimodal signals indicates multiplicative enhancement. Ó
Cross-modal integration of multimodal courtship signals in a wolf spider
Animal Cognition, 2016
Cross-modal integration, i.e., cognitive binding of information transmitted in more than one signal mode, is important in animal communication, especially in complex, noisy environments in which signals of many individuals may overlap. Males of the brush-legged wolf spider Schizocosa ocreata (Hentz) use multimodal communication (visual and vibratory signals) in courtship. Because females may be courted by multiple males at the same time, they must evaluate co-occurring male signals originating from separate locations. Moreover, due to environmental complexity, individual components of male signals may be occluded, altering detection of sensory modes by females. We used digital multimodal playback to investigate the effect of spatial and temporal disparity of visual and vibratory components of male courtship signals on female mate choice. Females were presented with male courtship signals with components that varied in spatial location or temporal synchrony. Females responded to spatially disparate signal components separated by C90°as though they were separate sources, but responded to disparate signals separated by B45°as though they originated from a single source. Responses were seen as evidence for cross-modal integration. Temporal disparity (asynchrony) in signal modes also affected female receptivity. Females responded more to male signals when visual and vibratory modes were in synchrony than either out-of-synch or interleaved/alternated. These findings are consistent with those seen in both humans and other vertebrates and provide insight into how animals overcome communication challenges inherent in a complex environment.
Behavioral Ecology and Sociobiology, 2019
Multimodal courtship signals may compensate for environmental interference or loss of signals in some sensory modes but may also increase detection by eavesdroppers. Studies on the wolf spider Schizocosa ocreata (Hentz) have demonstrated that males eavesdrop on visual courtship cues of other males and subsequently initiate courtship. Since S. ocreata males use multimodal courtship signals, we examined responses of males to playback of signals in different sensory modes (visual, vibration, multimodal) to test their relative importance for eavesdropping on courting male rivals. We used a recently developed technique to present male wolf spiders with video and/or vibratory stimuli: (1) a multimodal courting male stimulus, with synchronous visual and vibratory cues; (2) a visual-only courting male stimulus (minus the vibratory cues); (3) vibratory cues only (minus the visual cues); and (4) a control (visual background, no courtship). In single-presentation (no-choice) tests, males displayed more courtship bouts and longer durations of courtship bouts to the vibratory stimulus compared with either the visual or multimodal stimuli. However, in two-choice tests where isolated vibratory cues were paired against visual or multimodal stimuli, test males responded with more courtship bouts and longer durations of courtship bouts to the multimodal and visual stimuli. Results of these experiments suggest that male wolf spiders may vary eavesdropping courtship behaviors to compensate for missing sensory information concerning the location and other distinguishing characteristics of the rival male and the whereabouts of the female. Significance statement Social eavesdropping is used to exploit information in signals of conspecifics, e.g., as a means of mate competition. Studies on Schizocosa ocreata wolf spiders have shown that males eavesdrop on visual courtship displays of other males and subsequently initiate multimodal courtship. We used video/vibration playback to examine responses of males to signals in different sensory modes (visual, vibration, both) and determine their relative importance for eavesdropping on courting male rivals. Results suggest that depending on sensory modes of their rivals' signals, males may vary their own courtship displays to compensate for missing information. For example, when signals are presented individually, eavesdropping male response patterns are distinctly different from when presented a choice between modes. Males show more displays with isolated vibratory signals, but given a choice, males more often increase their tapping when multimodal cues were present. Ultimately, eavesdroppers that adjust behaviors in response to available sensory cues would be able to "level the playing field" with rivals and potentially increase the probability of gaining attention of females.
Animal Behaviour, 1999
Male wolf spiders within the genus Schizocosa display considerable variation in foreleg ornamentation as well as in courtship communication. Multiple modes of male signaling have evolved in a number of species. Divergence in courtship signals among species within this genus may be directly associated with variation in the sensory sensitivities of conspecific females. We isolated the visual and vibratory courtship cues of four species of Schizocosa and recorded conspecific female receptivity to each isolated cue. We also examined female receptivity to complete multimodal courtship signals. We found that the sensory sensitivities of conspecific females were associated with the predominant modes of male courtship communication. Species in which females use mostly stridulatory cues in assessing conspecific males tended to have stridulation-based male courtship displays (S. duplex and S. uetzi) while the opposite was true for species in which females used more visual cues in male assessment (S. stridulans and S. crassipes). This study suggests coevolution between male signal design and female sensory design. We discuss possible scenarios that could be driving this coevolution, including hypotheses of sensory bias and environmental constraints.
Flexibility in the multi-modal courtship of a wolf spider, Schizocosa ocreata
Journal of Ethology, 2005
Male Schizocosa ocreata wolf spiders court females with synchronous visual and seismic displays. We tested whether male S. ocreata modify their courtship in relation to light environment, and associated utility of the visual components. Males were generally more active and more likely to perform the major courtship element ("jerky tapping") when in the light. One courtship element ("arching") was only observed in the light while another ("vertical leg-extend") was only observed in the dark. Courtship in the dark retained "visual" components, suggesting spiders cannot disengage these components of multi-modal display even when superfluous. Once initiated, there was no evidence that performance rate or time spent in each courtship element differed in the light and in the dark.
Eavesdropping and signal matching in visual courtship displays of spiders
Biology Letters, 2012
Eavesdropping on communication is widespread among animals, e.g. bystanders observing malemale contests, female mate choice copying and predator detection of prey cues. Some animals also exhibit signal matching, e.g. overlapping of competitors' acoustic signals in aggressive interactions. Fewer studies have examined male eavesdropping on conspecific courtship, although males could increase mating success by attending to others' behaviour and displaying whenever courtship is detected. In this study, we show that field-experienced male Schizocosa ocreata wolf spiders exhibit eavesdropping and signal matching when exposed to video playback of courting male conspecifics. Male spiders had longer bouts of interaction with a courting male stimulus, and more bouts of courtship signalling during and after the presence of a male on the video screen. Rates of courtship (leg tapping) displayed by individual focal males were correlated with the rates of the video exemplar to which they were exposed. These findings suggest male wolf spiders might gain information by eavesdropping on conspecific courtship and adjust performance to match that of rivals. This represents a novel finding, as these behaviours have previously been seen primarily among vertebrates.
Brain, Behavior and Evolution, 2002
Spiders perceive the world using multiple sensory modes, including vibration, vision, and chemical senses, for prey detection and communication. These sensory modes are used in many communication contexts, either individually or in multimodal signaling. Selection for effective signaler-receiver communication and species discrimination is especially strong for these predatory and potentially cannibalistic arthropods, resulting in the evolution of considerable diversity in signaling behaviors. In this paper, we review sensory mechanisms involved in spider signaling and present an overview of recent work done on wolf spiders (Lycosidae) that use multimodal communication (simultaneous visual and vibratory signals) in sexual signals during courtship. The relative importance of visual and vibratory signaling modes, and the use of multiple modes varies among closely related species in the genus Schizocosa, providing a model system for investigating multisensory guidance of complex behavior. Here we examine previous and current research on responses of female spiders to components of male courtship behavior, using several experimental techniques including cue isolation (single sensory modes), video/audio digitization and playback, and cueconflict (mixed conspecific/heterospecific components) to tease apart elements of multimodal signaling.
acta ethologica, 2006
Males of many animal species are reproductively limited by the difficulty and time costs of finding mates. Males of such species should be selected to take advantage of any cues that might reveal the location of prospective mates. Cues to female location are not restricted to those produced by females, but might also include the highly apparent courtship displays of males that have already found a female. By "eavesdropping" on these courting rivals, initiating sexual displays when courting rivals are detected (i.e., social facilitation of displays); males might effectively exploit the mate-searching efforts of their rivals. We tested the possibility that male Schizocosa ocreata wolf spiders exhibit social facilitation of courtship behaviors using a combination of live behavioral trials and video playback with single stimulus presentations. When exposed to visual cues from another male, male S. ocreata can discern the presence of another individual whether that individual is courting or not. However, we found no evidence of social facilitation of courtship or chemoexploratory behaviors in response to seismic or visual cues presented in isolation or combined. While complex, multimodal, male courtship signals are important in mate choice by female S. ocreata, males do not appear to use these cues to socially facilitate their own courtship.