Journal of Comparative Physiology A

, Volume 191, Issue 8, pp 707–714 | Cite as

Mid-frequency suppression in the green treefrog (Hyla cinerea): mechanisms and implications for the evolution of acoustic communication

  • H. Carl GerhardtEmail author
  • Gerlinde Höbel
Original Paper


Advertisement calls of green treefrogs (Hyla cinerea) have two spectral peaks centered at about 1 kHz and 3 kHz. Addition of a component of intermediate frequency (1.8 kHz) to a synthetic call reduced its attractiveness to females relative to an alternative lacking this component. This mid-frequency suppression occurred over a 20-dB range of playback levels. Addition of other intermediate frequencies had weak effects on preferences at some playback levels, in some localities, and at lower-than-normal temperatures. These effects correlate well with the response properties of a population of low-frequency-tuned auditory neurons innervating the amphibian papilla. Males of a closely related species (H. gratiosa) produce calls with emphasized frequencies within the range of suppression in H. cinerea; however, suppression also occurred in localities well outside the area of geographical overlap with this species. Thus, previous speculation that mid-frequency suppression evolved to enhance species discrimination is probably incorrect. This phenomenon is more likely to reflect a general sensory bias in anurans and other vertebrates, tone-on-tone inhibition. Such negative biases, and other inhibitory mechanisms, almost certainly play an important role in the evolution of communication systems but have received far less attention than positive biases that enhance signal attractiveness.


Acoustic communication Mid-frequency suppression Sensory bias Tone-on-tone inhibition Temperature effects Hyla cinerea 



We thank R. L. Rodriguez, F. Breden, S. Humfeld and J. Schul for comments on the manuscript. Supported by National Institutes of Health (R01 DC05760) and National Science Foundation (IBN 91973) grants to HCG and travel and dissertation grants from the German Academic Exchange Service and Graduiertenfoerderung des Landes Baden-Wuerttemberg, Germany to GH. The experiments comply with the “Principles of animal care”, publications No. 86–23, revised 1985 of the National Institute of Health, and with the current law in the United States.


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Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  1. 1.Division of Biological SciencesUniversity of MissouriColumbiaUSA

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