Inter-sexual multimodal communication during mating in wild geladas: the leading role of females

Female primates can emit vocalizations associated with mating that can function as honest signals of fertility. Here, we investigated the role of mating calls and visual signals in female geladas Theropithecus gelada. Since females have a central role in the gelada society and seem to solicit sexual interactions, we answered whether they emit vocalizations in conjunction with gazing to increase mating success probability. Before and during copulations, females can emit pre-copulation calls and copulation calls. For the first time, we identified a new female vocalization emitted at the final stage of copulations (end-copulation call), possibly marking the occurrence of ejaculation. We found that longer pre-copulation call sequences were followed by both prolonged copulations and the presence of end-copulation calls thus suggesting that females use pre-copulation calls to ensure successful copula completion. Moreover, we found that different combinations of female vocal types and gazing had different effects on male vocal behavior and motivation to complete the copula. The analysis of the vocal and visual signals revealed a complex inter-sexual multimodal chattering with the leading role of females in the signal exchange. Such chattering, led by females, modulates male sexual arousal, thus increasing the probability of the copula success.

Not only a listener: female frog-biting midges (Corethrellidae) also distinguish the shape of frogs

It is well known that female adults of frog-biting midges (Corethrellidae) are attracted by anuran mating calls. However, the role of host-emitted cues other than mating calls in determining the level of attraction remains poorly understood. Here, we performed field playback experiments to test how the host-seeking behaviour of Corethrella Coquillett is influenced by different sound stimuli: mating call of a tree frog, cricket call, and no sound. Then, after long-distance host detection, we evaluated if Corethrella can distinguish landing sites by using at short distance the colour and/or shape of anurans. For that, we placed artificial models of frogs with different colours (light green and dark brown) and an artificial caterpillar model (light green colour) on the top of speakers. We found that only frog mating calls presented with the visual cue of an artificial frog were attacked by Corethrella, suggesting that frog shape, regardless of colour, is an important cue for the identification of its hosts. This is the first study providing evidence that after flying long distances guided by frog calls, Corethrella can identify their hosts using visual cues at short distances.

Effect of temperature on life-history traits and mating calls of a field cricket, Acanthogryllus asiaticus

Ectotherms are sensitive to the changes in ambient temperature with respect to their physiology and development. To compensate for the effects of variation in temperature, ectotherms exhibit physiological plasticity which can be for short or long term. An extensive body of literature exists towards understanding these effects and the solutions ectotherms have evolved. However, to what extent rearing temperature during early life stages impacts the behaviour expressed in adulthood is less clearly understood. In the present study, we aimed to examine the effect of developmental temperature on life-history traits and mating call features in a tropical field cricket, Acanthogryllus asiaticus. We raised A. asiaticus at two different developmental conditions: 25°C and 30°C. We found developmental time and adult lifespan of individuals reared at 30°C to be shorter than those at 25°C. Increased developmental temperature influenced various body size parameters differentially. Males raised at 30°C were found to be larger and heavier than those raised at 25°C, making A. asiaticus an exception to the temperature-size rule. We found a significant effect of the change in immediate ambient temperature on different call features of both field-caught and lab-bred individuals. In addition, developmental temperature also affected mating call features as individuals raised at higher temperature produced faster calls with a higher peak frequency compared to those raised at lower temperature. However, the interaction of both developmental and immediate temperature on mating calls showed differential effects. Our study highlights the importance of understanding how environmental temperature shapes life-history and sexual communication in crickets.

Female toads engaging in adaptive hybridization prefer high-quality heterospecifics as mates

Hybridization—interbreeding between species—is generally thought to occur randomly between members of two species. Contrary to expectation, female plains spadefoot toads (Spea bombifrons) can increase their evolutionary fitness by preferentially mating with high-quality males of another species, the Mexican spadefoot toad (Spea multiplicata). Aspects of Mexican spadefoot males’ mating calls predict their hybrid offspring’s fitness, and plains spadefoot females prefer Mexican spadefoot males on the basis of these attributes, but only in populations and ecological conditions where hybridization is adaptive. By selecting fitness-enhancing mates of another species, females increase hybridization’s benefits and exert sexual selection across species. Nonrandom mating between species can thereby increase the potential for adaptive gene flow between species so that adaptive introgression is not simply happenstance.

TrackUSF, a novel methodology for automated analysis of ultrasonic vocalizations, reveals modified social communication in a rat model of autism

Rodents emit various social ultrasonic vocalizations (USVs), which reflect their emotional state and mediate social interaction. USVs are usually analyzed by manual or semi-automated methodologies categorizing discrete USVs according to their structure in the frequency-time domains. This laborious analysis hinders effective use of USVs for screening animal models of human pathologies associated with modified social behavior, such as autism spectrum disorder (ASD). Here we present a novel, automated methodology for analyzing USVs, termed TrackUSF. To validate TrackUSF, we analyzed a dataset of mouse mating calls and compared the results with a manual analysis by a trained observer. We found that TrackUSF was capable of detecting most USVs, with less than 1% of false-positive detections. We then employed TrackUSF to social vocalizations in Shank3-deficient rats, a rat model of ASD and found, for the first time, that these vocalizations exhibit a spectrum of deviations from pro-social calls towards aggressive calls.