Has the evolution of complexity in the amphibian papilla influenced anuran speciation rates?

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72375/1/j.1420-9101.2006.01079.x.pd

Biogéographie de Madagascar = Biogeography of Madagascar

Les cris mâles du #Boophis madagascariensis) (#Rhacophoridae) ont été enregistrés dans son milieu naturel, la forêt tropicale humide de l'est de Madagascar. Nous les avons classés ensuite en 28 types différents. Bien que tous les cris "iambiques" soient considérés comme les variantes d'un même type, cette espèce en compte 8 à son actif, ce qui représente le plus large répertoire jamais réalisé pour les grenouilles. Des extraits de la bande témoin ont été utilisés comme stimuli afin d'établir la signification fonctionnelle de quelques types. Une séquence de la bande témoin a pour effet d'accélérer la vitesse d'émission des cris mâles ; une autre, de les suspendre alors que d'autres extraits ne modifient pas le son d'origine. La signification fonctionnelle d'un répertoire élargi des cris est discutée. (Résumé d'auteur

The phase response of primary auditory afferents in a songbird (Sturnus vulgaris L.)

The effects of stimulus frequency and intensity on phase-locking characteristics of cochlear ganglion cells were studied in the starling. All cells showed phase-locking to tone stimuli within their response area. Phase-locking at CF is found on average 9 dB below discharge rate threshold. Phase-locking is best at 0.4 kHz and deteriorates with increasing frequency almost independently of CF. No phase-locking was evident for test frequencies above 3–4 kHz. Phase-locking in cells with CFs above 1.0 kHz is better below CF than at CF. For constant sound pressure, an increase in stimulus frequency always produced an increase in phase lag of the neural response. The phase vs. frequency data obtained at constant sound pressure can be reasonably approximated by straight line functions. The slopes of these functions indicate the latency of the neural response, and are correlated with the CFs of the respective cells; the latency tends to be longer in low-CF cells and shorter in high-CF cells. The latency decreases by 0.04 ms per l dB sound pressure increase. The response phase at CF is nearly stimulus level-independent. Increasing stimulus intensity causes increasing phase lag below CF and decreasing phase lag above CF. These results are compared to findings in other vertebrates and demonstrate the similarities of phase-locking characteristics despite the substantial anatomical differences among the vertebrate groups

Anthropogenic substrate-borne vibrations impact anuran calling

Anthropogenic disturbance is a major cause of the biodiversity crisis. Nevertheless, the role of anthropogenic substrate vibrations in disrupting animal behavior is poorly understood. Amphibians comprise the terrestrial vertebrates most sensitive to vibrations, and since communication is crucial to their survival and reproduction, they are a suitable model for investigating this timely subject. Playback tests were used to assess the effects of substrate vibrations produced by two sources of anthropogenic activity– road traffic and wind turbines– on the calling activity of a naïve population of terrestrial toads. In their natural habitat, a buried tactile sound transducer was used to emit simulated traffic and wind turbine vibrations, and changes in the toads’ acoustic responses were analyzed by measuring parameters important for reproductive success: call rate, call duration and dominant frequency. Our results showed a significant call rate reduction by males of Alytes obstetricans in response to both seismic sources, whereas other parameters remained stable. Since females of several species prefer males with higher call rates, our results suggest that anthropogenically derived substrate-borne vibrations could reduce individual reproductive success. Our study demonstrates a clear negative effect of anthropogenic vibrations on anuran communication, and the urgent need for further investigation in this are