@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 {48153, title = {Cues for acoustic detection of prey: insect rustling sounds and the influence of walking substrate}, journal = {Journal of Experimental Biology}, volume = {211}, year = {2008}, month = {Jan-09-2008}, pages = {2799 - 2806}, abstract = {

When insects walk, they generally produce sounds. These can reveal the walkers\&$\#$39; presence and location to potential predators such as owls, bats and nocturnal primates. Additionally, predators might extract information on taxon, palatability, size or profitability from the rustling sounds. In contrast to ear morphology, hearing physiology and psychoacoustics of acoustically oriented predators, little attention has hitherto been paid to the acoustic structure and information content of prey sounds. An important element in the ecology of acoustic prey detection remained virtually unexplored: the influence of the substrate type on rustling sounds. In this study, we analysed amplitude and frequency parameters from insects walking on various natural substrates, in both Germany (Carabus beetles) and Madagascar (various beetles and cockroaches). The data show that rustling sound amplitude and frequency content depend on substrate type. On moist substrates arthropods produced less intense and less broadband rustling sounds than on dry substrates. Sound pressure level was reduced by about 6 dB, halving the detection range for the predator. For a given insect, rustling sound amplitude increased with walking speed. Finally, we found that the previously established correlation of arthropod size and rustling amplitude holds across multiple substrates. Based on these data, we provide for the first time estimates of realistic detection distances in the field. These distances range from below 1 m to over 13 m, depending on the substrate, insect mass, walking speed and background noise level. These estimates are crucial for an understanding of the foraging ecology, foraging efficiency and sensory ecology of acoustic predators.

}, keywords = {auditory, detection distance, foraging, hearing, prey detection, sensory ecology}, issn = {0022-0949}, doi = {10.1242/jeb.019596}, url = {http://jeb.biologists.org/cgi/doi/10.1242/jeb.019596https://syndication.highwire.org/content/doi/10.1242/jeb.019596}, author = {Goerlitz, H. R. and Greif, S. and Siemers, B. M.} } @article {48150, title = {The simple ears of noctuoid moths are tuned to the calls of their sympatric bat community}, journal = {Journal of Experimental Biology}, volume = {216}, year = {2013}, month = {Feb-04-20132149}, pages = {3954 - 3962}, abstract = {

nsects with bat-detecting ears are ideal animals for investigating sensory system adaptations to predator cues. Noctuid moths have two auditory receptors (A1 and A2) sensitive to the ultrasonic echolocation calls of insectivorous bats. Larger moths are detected at greater distances by bats than smaller moths. Larger moths also have lower A1 best thresholds, allowing them to detect bats at greater distances and possibly compensating for their increased conspicuousness. Interestingly, the sound frequency at the lowest threshold is lower in larger than in smaller moths, suggesting that the relationship between threshold and size might vary across frequencies used by different bat species. Here, we demonstrate that the relationships between threshold and size in moths were only significant at some frequencies, and these frequencies differed between three locations (UK, Canada and Denmark). The relationships were more likely to be significant at call frequencies used by proportionately more bat species in the moths\&$\#$39; specific bat community, suggesting an association between the tuning of moth ears and the cues provided by sympatric predators. Additionally, we found that the best threshold and best frequency of the less sensitive A2 receptor are also related to size, and that these relationships hold when controlling for evolutionary relationships. The slopes of best threshold versus size differ, however, such that the difference in threshold between A1 and A2 is greater for larger than for smaller moths. The shorter time from A1 to A2 excitation in smaller than in larger moths could potentially compensate for shorter absolute detection distances in smaller moths.

}, keywords = {allotonic frequency hypothesis, constant-frequency echolocation, horseshoe bats, predator{\textendash}prey interactions, sensory ecology}, issn = {0022-0949}, doi = {10.1242/jeb.093294}, url = {http://jeb.biologists.org/cgi/doi/10.1242/jeb.093294https://syndication.highwire.org/content/doi/10.1242/jeb.093294}, author = {ter Hofstede, H. M. and Goerlitz, H. R. and Ratcliffe, J. M. and Holderied, M. W. and Surlykke, A.} } @article {48148, title = {Global warming alters sound transmission: differential impact on the prey detection ability of echolocating bats}, journal = {Journal of The Royal Society Interface}, volume = {11}, year = {2013}, month = {Feb-07-20132184}, abstract = {

Climate change impacts the biogeography and phenology of plants and ani- mals, yet the underlying mechanisms are little known. Here, we present a functional link between rising temperature and the prey detection ability of echolocating bats. The maximum distance for echo-based prey detection is physically determined by sound attenuation. Attenuation is more pronoun- ced for high-frequency sound, such as echolocation, and is a nonlinear function of both call frequency and ambient temperature. Hence, the prey detection ability, and thus possibly the foraging efficiency, of echolocating bats and susceptible to rising temperatures through climate change. Using present-day climate data and projected temperature rises, we modelled this effect for the entire range of bat call frequencies and climate zones around the globe. We show that depending on call frequency, the prey detection volume of bats will either decrease or increase: species calling above a cross- over frequency will lose and species emitting lower frequencies will gain prey detection volume, with crossover frequency and magnitude depending on the local climatic conditions. Within local species assemblages, this may cause a change in community composition. Global warming can thus directly affect the prey detection ability of individual bats and indirectly their interspecific interactions with competitors and prey.

}, keywords = {echolocation, foraging, global warming, sensory ecology, species interactions}, issn = {1742-5689}, doi = {10.1098/rsif.2013.0961}, url = {http://rsif.royalsocietypublishing.org/cgi/doi/10.1098/rsif.2013.0961https://syndication.highwire.org/content/doi/10.1098/rsif.2013.0961}, author = {Luo, J. and Koselj, K. and Zsebok, S. and Siemers, B. M. and Goerlitz, H. R.} }