Cicada ear geometry: species and sex effects |
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Authors: | JÉRÔME SUEUR SOLÈNE JANIQUE CAROLINE SIMONIS JAMES F. C. WINDMILL MICHEL BAYLAC |
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Affiliation: | 1. Muséum national d'Histoire naturelle, Département Systématique et Evolution CNRS UMR 7205 OSEB, 45 rue Buffon, 75005 Paris, France;2. Current address, Department of Biology, Faculty of Science, Mahidol University, Rama VI Road, 10400, Bangkok, Thailand.;3. Muséum national d'Histoire naturelle, Département Ecologie et Gestion de la Biodiversité, CNRS UMR 7179, 57 rue Buffon, 75005 Paris, France;4. Centre for Ultrasonic Engineering, Department of Electronic and Electrical Engineering, University of Strathclyde, Royal College Building, 204 George Street, Glasgow, G1 1XW, UK;5. Muséum national d'Histoire naturelle, CNRS, UMS 2700, Plate‐forme Morphométrie, 45 rue Buffon, 75005 Paris, France |
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Abstract: | Many insect species rely on their sense of audition to find a mate, to localize prey or to escape from a predator. Cicadas are particularly known for their loud call and the conspicuous tympanal hearing system located in their abdomen. The vibration pattern of the tympanal membrane (TM) has been investigated recently revealing mechanical properties specific to species and sex. Although TM size and shape is likely to affect these patterns, the geometry of the cicada ear has never been examined per se. Focusing on three Mediterranean cicada species, namely Cicadatra atra, Cicada orni and Lyristes plebejus, we investigated the structure of TM shape variation at two levels, within and across species. Applying an elliptic Fourier analysis to the outlines of both male and female TMs, we estimated sexual dimorphism and species effects. Cicadatra atra showed a large TM compared with its small size, probably as a result of selective constraints related to the role of the TM in sound production. Sexual dimorphism seemed to be greater than interspecific variation, indicating that constraints operating on sex might be more selective than those acting on species identification. In addition, C. orni appeared to be significantly different from the two other species. This morphological peculiarity could be related to the unique vibrational pattern of its membrane. This would establish for the first time a direct link between the shape and mechanism of a hearing organ. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 922–934. |
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Keywords: | audition cicada elliptical Fourier analysis geometric morphometrics tympanum |
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