Sex Steroid-Dependent Modulation of Acoustic Communication Systems in Fishes

Abstract

Acoustic communication is widespread among fishes, the largest extant group of vertebrates, and in many vocal teleost species it is essential for their reproductive and social behaviors. Recent evidence suggests that a fish’s internal hormonal state can profoundly influence its ability to produce and perceive social acoustic signals. Here, we review the current knowledge of how sex steroids can influence the auditory capabilities and vocal motor production of acoustic social signals in two incipient model teleosts, the plainfin midshipman fish Porichthys notatus and the African cichlid Astatotilapia burtoni. Studies of these model systems show that steroid-mediated improvements in vocal-acoustic processing are typically associated with reproductive readiness. This especially holds true for species that rely heavily on acoustic signaling during seasonal breeding such as the midshipman fish, as well as non-seasonally breeding species like cichlids that appear to use sound production as one component of a more complex multimodal courtship repertoire. Evidence for reproductive-state dependent plasticity in midshipman and cichlids is supported by changes in gonadal state, circulating sex-steroids (testosterone, 11-ketotestosterone, and estradiol), and steroid receptor expression in peripheral and central auditory structures that are concurrent with changes in auditory sensitivity and vocal motor production. This form of steroid-dependent vocal-acoustic plasticity is proposed to be an evolutionary labile solution for enhancing the detection and production of social acoustic signals. The abundance and diversity of vocal fish present unique future opportunities to explore how this solution may have shaped sexual selection and the evolution of acoustic communication systems in fishes.