@article {57944, title = {Sensory evolution of hearing in tettigoniids with differing communication systems}, journal = {Journal of Evolutionary Biology}, volume = {27}, year = {2014}, month = {Jan-01-2014}, pages = {200 - 213}, abstract = {

In Tettigoniidae (Orthoptera: Ensifera), hearing organs are essential in mate detection. Male tettigoniids usually produce calling songs by tegminal stridu- lation, whereas females approach the males phonotactically. This unidirec- tional communication system is the most common one among tettigoniids. In several tettigoniid lineages, females have evolved acoustic replies to the male calling song which constitutes a bidirectional communication system. The genus Poecilimon (Tettigoniidae: Phaneropterinae) is of special interest because the ancestral state of bidirectional communication, with calling males and responding females, has been reversed repeatedly to unidirec- tional communication. Acoustic communication is mediated by hearing organs that are adapted to the conspecific signals. Therefore, we analyse the auditory system in the Tettigoniidae genus Poecilimon for functional adapta- tions in three characteristics: (i) dimension of sound-receiving structures (tympanum and acoustic spiracle), (ii) number of auditory sensilla and (iii) hearing sensitivity. Profound differences in the auditory system correlate with uni- or bidirectional communication. Among the sound-receiving structures, the tympana scale with body size, whereas the acoustic spiracle, the major sound input structure, was drastically reduced in unidirectional communicating species. In the unidirectional P. ampliatus group, auditory sensilla are severely reduced in numbers, but not in the unidirectional P. propinquus group. Within the P. ampliatus group, the number of auditory sensilla is further reduced in P. intermedius which lost acoustic signalling due to parthenogenesis. The auditory sensitivity correlated with the size of the acoustic spiracle, as hearing sensitivity was better with larger spiracles, espe- cially in the ultrasonic range. Our results show a significant reduction in auditory structures, shaped by the differing sex roles during mate detection.

}, keywords = {animal communication, insect hearing, regressive evolution, sensory ecology, sensory evolution, tympanal organ}, doi = {10.1111/jeb.2014.27.issue-110.1111/jeb.12294}, url = {http://doi.wiley.com/10.1111/jeb.2014.27.issue-1}, author = {Strau{\ss}, J. and Lehmann, A. W. and Gerlind U.C. Lehmann} } @article {20904, title = {Evolutionary diversification of the auditory organ sensilla in Neoconocephalus katydids (Orthoptera: Tettigoniidae) correlates with acoustic signal diversification over phylogenetic relatedness and life history}, journal = {Journal of Evolutionary Biology}, year = {2017}, month = {Jan-03-2017}, abstract = {

Neoconocephalus tettigoniids are a model for the evolution of acoustic signals as male calls have diversified in temporal structure during the radiation of the genus. Tettigoniidae have hearing organs in the forelegs with species-specific numbers of auditory sensilla in a linear crista acustica. We investigated changes of the hearing organs during an evolutionary radiation with divergence of intraspecific acoustic signals. We compared the neuroanatomy of the crista acustica from 9 Neoconocephalus species with different temporal call features, life histories, and from different phylogenetic positions. Average numbers of auditory sensilla were species-specific, ranging between 32\–35 sensilla. It is likely under sexual selection for detection of male calls and natural selection for detection of bat calls. We found statistically significant differences in sensillum numbers among species, but no relationship of crista acustica length or sensillum number with phylogenetic position or life history. Statistically significant correlations existed with call patterns: species with slow pulse rates had significantly higher numbers of auditory sensilla and a longer crista acustica. Further, species with a derived double-pulsed calls had longer cristae, and continuous callers had a higher number of auditory sensilla. Correlations with crista length were stronger than with the number of auditory sensilla. The hearing organs show considerable diversity between species despite their recent divergence and morphological and ecological similarities. Thus, they have the potential to respond to various selective pressures, including divergence of temporal and spectral signal properties. Phylogenetic constraints are unlikely to limit the evolutionary change of the auditory systems.

}, keywords = {hearing organ, insects, radiation, sensory evolution, sexual selection, signal evolution, tympanal organ}, doi = {10.1111/jeb.13066}, url = {http://doi.wiley.com/10.1111/jeb.13066}, author = {Strau{\ss}, Johannes and Alt, Joscha A. and Ekschmitt, Klemens and Schul, Johannes and Lakes-Harlan, Reinhard} }