The vocal sac increases call rate in the Tungara frog Physalaemus pustulosus.

Full Abstract

In most anurans, the production of advertisement calls is accompanied by the inflation of a vocal sac. Current functions of the vocal sac, however, are not fully understood, although several hypotheses have been proposed. One hypothesis suggests that the vocal sac decreases the intercall interval (i.e., increases call rate) by reinflating the lungs more rapidly than is possible with the buccal pump. We investigate this hypothesis by analyzing audio and video recordings of calling tungara frogs. We compare the first two call bouts emitted by an originally uninflated male. The first call bout requires lung inflation via buccal pumping, but in the second, the male is already inflated because of capture of air and reinflation of the lungs by the vocal sac. Lung inflation to typical field levels requires 26-51 buccal pumps, which takes at least 4.4 s. This estimate is more than 2.5 times the typical intercall interval with lung reinflation via a vocal sac (ca. 1.7 s). Evidence from phonotaxis tests demonstrates that these differences in intercall intervals are salient to females and that female Physalaemus pustulosus prefer the shorter intercall interval/higher call rate. Acoustic analyses demonstrate that the first call of bout 1, which requires buccal pumping, is usually shorter, of lower amplitude, and spans a smaller frequency range than the first call of bout 2, which does not require buccal pumping. Because females prefer longer, more intense calls, these results suggest that the vocal sac not only increases call rate but also allows males to produce more calls of increased attractiveness to females.

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Author information

Author/s: Pauly, Gregory B (GB); Bernal, Ximena E (XE); Rand, A Stanley (AS); Ryan, Michael J (MJ);

Affiliation: Section of Integrative Biology, University of Texas, Austin, 78712, USA. gbpauly(-atsign-)mail.utexas.edu

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.

Journal: Physiological and biochemical zoology : PBZ (Physiol Biochem Zool), published in United States. (Language: eng)

Reference: -2006 Jul-Aug; vol 79 (issue 4) : pp 708-19

Dates: Created 2006/07/07; Completed 2006/09/13; Revised 2006/11/15;

PMID: 16826497, status: MEDLINE (last retrieval date: 12/26/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Acoustics
Animals
Male

Male
Ranidae - anatomy & histology; physiology
Vocalization, Animal - physiology

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