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PhD-Position "Evolution of directional hearing in crickets" Prof.Römer

Starting September 2013, a PhD-position for three years will be available in my group, dealing with the evolution of directional hearing in crickets. The applicant should have interest in a project combining various approaches (morphology, neurophysiology, laser-vibrometry, acoustic biophysics and modelling). The summary of the project funded by the Austrian Science Foundation (FWF) is given below. For further information please contact:






Prof. Dr. Heiner RÖMER
Institut für Zoologie
KARL-FRANZENS-UNIVERSITÄT GRAZ
8010 Graz, Universitätsplatz 2
phone:++43/ 0316/380/5596,
Fax:++43/ 0316/380/9875
Email: heinrich.roemer@uni-graz.at

Summary
Sound localization in small insects can be a challenging task due to imposed physical constrains in deriving sufficiently large intensity differences between both ears (IIDs). In crickets, sound source localization is based on a complicated biophysical mechanism using a modified tracheal system connecting the tympana of both ears with an external sound entrance. These acoustic trachea form the basis of a pressure difference receiver; it responds to the interaction of three different sound components at the site of the tympanum, with the result of a directionality of the ear despite an unfavorable relationship between the wavelength of sound and body size.
In a previous survey on different cricket species predominantly of the tropical rainforest, we found large morphological differences of the acoustic tracheal apparatus subserving directionality.  What are the factors, the biophysical and environmental constraints accounting for these differences, and how did the pressure difference receiver in crickets evolve at all? What have been the evolutionary precursors of the system, and what are the modifications which provide highest directionality of the system? The current proposal aims to investigate its evolution using anatomical, neurophysiological, biophysical and modelling approaches. We will compare anatomical variation in the acoustic tracheal system of primary non-hearing species with those using elaborate acoustic signalling, and species with secondary loss of sound communication

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