Subterranean Fishes of the World

3252

2017

AIM 2017

Acoustic communication is an essential feature to exchange information related to social cohesion and coordination (i.e.: alarm calls, mother-youth interaction, sexual selection) and thus, survival, in many vertebrates. In fish, behaviours like territory defence, reproduction and speciation processes involve acoustic functions. However, little is known on how acoustic communication evolved. The physiological, morphological and behavioural adaptations reported in blind cavefish (CF) compared to its river-dwelling conspecific surface fish (SF), makes Astyanax mexicanus a good model to investigate the evolution of acoustic communication. We hypothesised that acoustic communication has evolved in CF, to compensate for the lack of visual modality in the dark. We first recorded and analysed SF and Pachón CF sounds in laboratory controlled conditions. We identified a panel or repertoire of 6 specific simple and complex sounds. Qualitative analyses of acoustic parameters showed that SF and CF share a common acoustic repertoire but, quantitative measures revealed a differential use of this repertoire in the two morphotypes, which also depends on the context. We are now investigating the "meaning" of these sounds in terms of communication in various contexts (i.e.: solo, duo or groups discovering new environments, after habituation period and with Astyanax-playback stimulations). Moreover, long acoustic and video recordings performed in Pachón, Subterráneo and Tinaja caves during field expeditions revealed similar sounds produced by CF in their natural environment. Altogether, the results of this work suggest that acoustic communication could play an important role in CF adaptation to survive after drastic environmental changes.

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