Academic literature on the topic 'Multimodal Duetting'

This review represents complex mechanisms and processes of multimodal communication in stink bugs. During reproductive behavior the airborne and substrate-borne signals enable mate recognition, mediate directionality of movement, eliminate rivals and motivate partners for copulation. Species specific characteristics prevent hybridization at various levels of mating behavior. Male sex and/or aggregation pheromones as uni- or multicomponent signals attract mates to land on the same plant and there, trigger females to call males by vibratory signals, transmitted through the plant. Communication during courtship runs at short distance with visual, airborne, substrate-borne and contact chemical and mechanical signals. Abdomen vibrations produce the main repertoire of female and male calling, courtship and rival vibratory signals. To increase their informational value, stink bugs tune signal frequency, amplitude and temporal characteristics with mechanical properties of plants. The airborne component of species non-specific and high amplitude signals, produced by body tremulation and wing buzzing enables communication contact between mates standing on mechanically isolated plants. Female vibratory signals increase the amount of male emitted pheromone and the latter keeps female calling. Interaction, synergy and characteristics of visual, contact chemical and vibratory signals, exchanged during courtship remain under-investigated. Female and male competition for access to copulation in imbalanced sex conditions is characterized by duetting with rival song vibratory signals. Different receptors in and on different parts of the body are able to detect with high sensitivity multimodal airborne and substrate-borne communication signals. The relevance of the multimodal communication for the reproductive success of stink bugs is discussed.

Duetting is a behaviour observed in some animal species, in which both males and females participate in signalling to find mates. It may have evolved as an adaptation to reduce the costs associated with mate-finding behaviours, such as predation risk. Duetting systems allow estimation of sex-specific predation risks of signalling and searching in the same species, giving insights into the selective forces acting on these behaviours. Using an acoustic–vibratory duetting katydid, Onomarchus uninotatus , and its bat predator, Megaderma spasma , we estimated the sex-specific predation costs of different mate-finding behaviours, such as walking, flying and signalling, by conducting experiments with untethered live katydids and bats. We found that acoustic–vibratory duetting benefits both the sexes as a low-risk mate-finding strategy.

The evolution of human language is a topic that has received undiminished attention. Numerous hypotheses for the origin of human language have been proposed, including gestural communication found specifically among apes. This study advances the hypothesis that human evolution, including human language development, is three-pronged: prosocial, cognitive, and collaborative. Duetting and turn-taking in primates are used as pivotal examples of how bonding leads to joint action and collaboration. It points out that such vocal behavior itself may be a crucial precursor of language evolution in the sense that it is explicitly focused on a conspecific. Some current hypotheses have acknowledged duetting as an important perceptual and behavioral example of synchronicity. Some forms of synchronized behavior, as found in duetting, synchronized dance, or even shared song, were perhaps crucial evolutionary steps preceding the evolution of human language. Duetting signifies more than that, however, because it is an observable and significant cognitive investment that signals attention toward a partner. This study also advances the hypothesis that affect and cognition would have needed to precede any form of duetting or signs of affiliation such as grooming. Hence, this study, asking what duetting in primates signifies in evolutionary terms, takes a multidisciplinary and multimodal approach to suggest important affective and cognitive steps in the evolution of human language and speech, the chief of which is prosociality. Prosociality, as an attitude and awareness of another, be this as a friend or partner for whom one can do favors or whom one can help, is a model for collaboration and cooperation, and also increased cognition.

The spatial distribution of cooperating individuals plays a strategic role in territorial interactions of many group-living animals, and can indicate group cohesion. Vocalizations are commonly used to judge the distribution of signallers, but the spatial resolution of sounds is poor. Many species therefore accompany calls with movement; however, little is known about the role of audio-visual perception in natural interactions. We studied the effect of angular separation on the efficacy of multimodal duets in the Australian magpie-lark, Grallina cyanoleuca . We tested specifically whether conspicuous wing movements, which typically accompany duets, affect responses to auditory angular separation. Multimodal playbacks of duets using robotic models and speakers showed that birds relied primarily on acoustic cues when visual and auditory angular separations were congruent, but used both modalities to judge separation between the signallers when modalities were spatially incongruent. The visual component modified the effect of acoustic separation: robotic models that were apart weakened the response when speakers were together, while models that were together strengthened responses when speakers were apart. Our results show that responses are stronger when signallers are together, and suggest that males were are able to bind information cross-modally on the senders' spatial location, which is consistent with a multisensory illusion.

The spectacular diversity in the pair-formation strategies among animal groups has attracted the attention of many over the years. The roots of this diversity lie in the diversity of challenges that males and females face in finding a potential mate. Successful localisation of mates requires effective information flow between the sexes regarding location, availability and, in some cases, quality. To this end, animals have evolved different kinds of signals, signalling and search strategies to counter the various challenges and facilitate encounter. A major factor affecting the information flow between the sexes is the spatio-temporal distribution of the sexes, as signals and sensory physiologies are constrained spatio-temporally. The spatio-temporal distribution of males and females is in turn a function of two major factors: resource distribution and parental investment of the sexes. Depending on whether the resource distribution is patchy or uniform, individuals can be clumped in space or evenly dispersed, influencing their pair-formation strategies. Parental investment can further alter the relative distribution of males and females by affecting the time that males and females can be sexually receptive. Higher parental investment of a particular sex can lead to these individuals being out of the mating pool longer, causing a bias in the ratio of sexually receptive males to females (Operational Sex Ratio) at any given point in time, consequently impacting pair-formation strategies. Orthopterans are well known models for studies on acoustic communication owing to the diversity in signals and pair-formation strategies. Conventionally, males function as the static signalling sex and use long-range acoustic signals to direct the phonotactic response of silent females. There are deviations observed, with females responding to calling males via acoustic signals, with males (or both males and females) performing localisation. Onomarchus uninotatus, a canopy inhabiting paleotropical false-leaf katydid, presents a unique departure, wherein the two sexes employ signals that function at different spatial scales. Males broadcast long- range acoustic signals and the females respond via vibratory signals that are then used by males to localise females. Laboratory experiments have established vibratory signals to be an immediate response to male calls even at the threshold of female hearing. Being a canopy species, relying on short-range vibratory signals for localisation across trees and at larger distances appears paradoxical. In my thesis, I therefore investigated the localisation strategies of Onomarchus uninotatus across two spatial scales, i.e. within and between trees, and aimed to understand if the roles played by the sexes are reflected in their relative parental investment. For the across-tree scale, I studied the spatial structure of calling males and their preferred calling sites (Artocarpus spp.) in their natural habitat. Using the information on male spacing, call transmission and hearing thresholds, I computed the perceptual spaces of male signals to understand the acoustic environment of calling males and females. It was found that both calling males and females could hear calls of males from neighbouring trees with a probability of 0.76 and 0.59 respectively. Although males were found to be dispersed, significant overlap was seen in their acoustic ranges. I then investigated female flight responses to male acoustic signals in laboratory experiments, wherein male acoustic signals were played back from loudspeakers that were not connected to the substrate on which the females were placed. Females typically tremulated first, followed sometimes by initiation of flight, suggesting that females may perform flight phonotaxis to locate calling males on a different tree. Using the information gathered from these studies, I then used a simulation framework to elucidate optimal mate encounter strategies at the across-tree spatial scale. The across-tree spatial distribution of the sexes was varied in the simulations and the encounter efficiencies quantified for different movement patterns of both males and females, using the data on spatio- acoustic patterning of callers in this system. Stationary calling males with localising females was found to be the optimal strategy across all spatial distributions. To understand pair-formation strategies at the within-tree spatial scale, field experiments were conducted in a semi-natural setup to observe interactions between a calling male and a responsive female at two different distances on a branch. Interestingly, females always tremulated first, irrespective of their distance from the caller. At larger distances, some females were found to perform phonotaxis, but only after a bout of tremulation. Finally, I examined the relative parental investment of the sexes using re-signalling intervals as a proxy. Given that both males and females invest in localisation, parental investments of the sexes were predicted to be comparable. Preliminary results from re-signalling intervals indicate that the sexes have comparable parental investment in this species.