The Computational Mechanisms of Mate Choice

A lateralized functional auditory network is involved in anuran sexual selection

Right ear advantage (REA) exists in many land vertebrates in which the right ear and left hemisphere preferentially process conspecific acoustic stimuli such as those related to sexual selection. Although ecological and neural mechanisms for sexual selection have been widely studied, the brain networks involved are still poorly understood. In this study we used multi-channel electroencephalographic data in combination with Granger causal connectivity analysis to demonstrate, for the first time, that auditory neural network interconnecting the left and right midbrain and forebrain function asymmetrically in the Emei music frog (Babina daunchina), an anuran species which exhibits REA. The results showed the network was lateralized. Ascending connections between the mesencephalon and telencephalon were stronger in the left side while descending ones were stronger in the right, which matched with the REA in this species and implied that inhibition from the forebrainmay induce REA partly. Connections from the telencephalon to ipsilateral mesencephalon in response to white noise were the highest in the non-reproductive stage while those to advertisement calls were the highest in reproductive stage, implying the attention resources and living strategy shift when entered the reproductive season. Finally, these connection changes were sexually dimorphic, revealing sex differences in reproductive roles.

Multimodality: a way to cope with road traffic noise? The case of European treefrog (Hyla arborea)

In the last decades, traffic noise has become a new challenge for efficient animal communication and several studies suggest that it is involved in population declines. Although poorly investigated in a traffic noise context, communication is generally multimodal, which can be viewed as a way to improve communication efficiency by allowing shift from a sensory modality to another when one modality suffers from noise. In the present study, we investigated multimodal shift in the European treefrog (Hyla arborea), a species using both acoustic and visual cues during male quality assessment task performed by females. Females were used in a discrimination task in two environmental conditions: with or without traffic noise. In traffic noise conditions, we showed that females' reliance on acoustic signal embedded in noise pollution did not decrease in favour of visual signals, therefore showing that females do not shift between modalities in response to traffic noise. Although, we did not evidence multimodal shift in our study, many species facing traffic noise present multimodal communication, and should be investigated to evaluate the importance of multimodal shift as a way to cope with traffic noise pollution.

Ten unanswered questions in multimodal communication

The study of multimodal communication has become an active and vibrant field. This special issue of Behavioral Ecology and Sociobiology brings together new developments in this rapidly expanding area. In this final contribution to the special issue, I look to the future and discuss ten questions in need of further work, touching on issues ranging from theoretical modeling and the evolution of behavior to molecular mechanisms and the development of behavior. In particular, I emphasize that the use of multimodal communication allows animals to switch between sensory channels when one channel becomes too noisy, and suggest that a better understanding of this process may help us both to understand the evolution of multisensory signaling and to predict the success of species facing environmental changes that affect signaling channels, such as urbanization and climate change. An expanded section is included on the effects of climate change on animal communication across sensory channels, urging researchers to pursue this topic due to the rapidity with which the environment is currently transforming.