02304nas a2200181   4500008004100000245008200041210006900123520165300192653002701845653001601872653001201888653002401900653002001924100002501944700001401969700001901983856012002002       2011                        eng d00aHigh background noise shapes selective auditory filters in a tropical cricket0 aHigh background noise shapes selective auditory filters in a tro3 a<p>Because of call frequency overlap and masking interference, the airborne sound channel represents a limited resource for communication in a species-rich cricket community like the tropical rainforest. Here we studied the frequency tuning of an auditory neuron mediating phonotaxis in the rainforest cricket Paroecanthus podagrosus, suffering from strong competition, in comparison with the same homologous neuron in two species of European field crickets, where such competition does not exist. As predicted, the rainforest species exhibited a more selective tuning compared with the European counterparts. The filter reduced background nocturnal noise levels by 26 dB, compared with only 16 and 10 dB in the two European species. We also quantified the performance of the sensory filter under the different filter regimes by examining the representation of the species-specific amplitude modulation of the male calling song, when embedded in background noise. Again, the filter of the rainforest cricket performed significantly better in terms of representing this important signal parameter. The neuronal representation of the calling song pattern within receivers was maintained for a wide range of signal-to-noise ratios because of the more sharply tuned sensory system and selective attention mechanisms. Finally, the rainforest cricket also showed an almost perfect match between the filter for sensitivity and the peripheral filter for directional hearing, in contrast to its European counterparts. We discuss the consequences of these adaptations for intraspecific acoustic communication and reproductive isolation between species.</p>
10aacoustic communication10acompetition10acricket10adirectional hearing10aMatched filters1 aSchmidt, Arne, K. D.1 aRiede, K.1 aRömer, Heiner  uhttp://jeb.biologists.org/cgi/doi/10.1242/jeb.053819https://syndication.highwire.org/content/doi/10.1242/jeb.05381902436nas a2200229   4500008004100000022001400041245008800055210006900143260001600212300001600228490000800244520157900252653002701831653001901858653002701877653002901904653002001933653002301953100002501976700001902001856018602020       2016                        eng d  a0022-094900aFunctional relevance of acoustic tracheal design in directional hearing in crickets0 aFunctional relevance of acoustic tracheal design in directional   cMar-10-2017  a3294 - 33000 v2193 a<p>Internally coupled ears (ICEs) allow small animals to reliably determine the direction of a sound source. ICEs are found in a variety of taxa, but crickets have evolved the most complex arrangement of coupled ears: an acoustic tracheal system composed of a large cross-body trachea that connects two entry points for sound in the thorax with the leg trachea of both ears. The key structure that allows for the tuned directionality of the ear is a tracheal inflation (acoustic vesicle) in the midline of the cross-body trachea holding a thin membrane (septum). Crickets are known to display a wide variety of acoustic tracheal morphologies, most importantly with respect to the presence of a single or double acoustic vesicle. However, the functional relevance of this variation is still not known. In this study, we investigated the peripheral directionality of three co-occurring, closely related cricket species of the subfamily Gryllinae. No support could be found for the hypothesis that a double vesicle should be regarded as an evolutionary innovation to (1) increase interaural directional cues, (2) increase the selectivity of the directional filter or (3) provide a better match between directional and sensitivity tuning. Nonetheless, by manipulating the double acoustic vesicle in the rainforest cricket Paroecanthus podagrosus, selectively eliminating the sound-transmitting pathways, we revealed that these pathways contribute almost equally to the total amount of interaural intensity differences, emphasizing their functional relevance in the system.</p>
10aacoustic communication10ainsect hearing10aInternally coupled ear10alaser Doppler vibrometry10aMatched filters10aSound localization1 aSchmidt, Arne, K. D.1 aRömer, Heiner  uhttp://jeb.biologists.org/lookup/doi/10.1242/jeb.145524https://syndication.highwire.org/content/doi/10.1242/jeb.145524https://syndication.highwire.org/content/doi/10.1242/jeb.145524