Seasonal variation in the frequency response of the ear: Implications for communication

Abstract

Seasonal variation in vocal‐acoustic behavior is well known among nonmammalian vertebrates; however, studies of the neural mechanisms underlying such seasonal variation have focused mainly on the anatomical rather than the neurophysiological correlates of seasonal reproductive periodicity. In this talk, I present the neurophysiological evidence for seasonal variation in the frequency response of the ear in the plainfin midshipman fish (Porichthys notatus). Vocal communication is essential to the reproductive success of the seasonally breeding midshipman fish, which migrates during the late spring and summer from deep ocean sites into the shallow intertidal zone to breed. Female midshipman fish use the auditory sense to detect and locate males that are singing from their nests. The seasonal onset of male mate calling in the midshipman fish coincides with a dramatic increase in the range of frequency sensitivity of the female’s saccule, the midshipman’s main organ of hearing, thus leading to increased encoding of the male’s mate call. I will present evidence for a steroid‐dependent mechanism that leads to this form of auditory plasticity and discuss why this plasticity of peripheral auditory frequency sensitivity may represent an adaptation to enhance the acquisition of auditory information needed for mate identification and localization during the breeding season.