Acoustic communication, reproduction and hormone modulation in the Catonotus darters

Abstract

Acoustic communication is an essential part of life for a variety of living beings. Acoustic communication is known to be essential to reproduction in mammals, birds, amphibians, insects and fish. Recently there have been many papers published that bring to light the extensive acoustic repertoire of freshwater fishes. However, studies of how this method of communication is used with the environment and the details of the physiological responses to this communication modality are somewhat less common. This dissertation will attempt to answer these questions using two species of darters in the sub-genus Catonotus. This will be the first documentation of vocalizations in Etheostoma neopterum and the first to make a direct comparison of the temporal and spectral components of vocalizations recorded in the laboratory and those recorded in the field. In addition, the hearing sensitivities of these fish and the acoustics of their freshwater stream environment will be examined. This dissertation will also be the first documentation of allopaternal care and the costs of reproduction in male E. neopterum. Finally this dissertation will examine the physiological endocrine response of male and female E. crossopterum to playbacks of male and female vocalizations. This will be done by using a non-invasive protocol which isolates free estradiol, testosterone, cortisol and 11-ketotestoerone from the holding water of fishes. These collections will be done before and after exposure to conspecific courtship or aggressive vocalizations. These investigates will help to form a clearer picture of how acoustics are used in concert with reproductive behaviors in Catonotus darters.