02531nas a2200133 4500008004100000245007900041210006900120520206600189100002902255700002302284700001902307700001802326856005302344 2008 eng d00aMatched Filters, Mate Choice and the Evolution of Sexually Selected Traits0 aMatched Filters Mate Choice and the Evolution of Sexually Select3 a

Background: Fundamental for understanding the evolution of communication systems is both the variation in a signal and how this affects the behavior of receivers, as well as variation in preference functions of receivers, and how this affects the variability of the signal. However, individual differences in female preference functions and their proximate causation have rarely been studied.

Methodology/Principal Findings: Calling songs of male field crickets represent secondary sexual characters and are subject to sexual selection by female choice. Following predictions from the ‘‘matched filter hypothesis’’ we studied the tuning of an identified interneuron in a field cricket, known for its function in phonotaxis, and correlated this with the preference of the same females in two-choice trials. Females vary in their neuronal frequency tuning, which strongly predicts the preference in a choice situation between two songs differing in carrier frequency. A second ‘‘matched filter’’ exists in directional hearing, where reliable cues for sound localization occur only in a narrow frequency range. There is a strong correlation between the directional tuning and the behavioural preference in no-choice tests. This second ‘‘matched filter’’ also varies widely in females, and surprisingly, differs on average by 400 Hz from the neuronal frequency tuning.

Conclusions/Significance: Our findings on the mismatch of the two ‘‘matched filters’’ would suggest that the difference in these two filters appears to be caused by their evolutionary history, and the different trade-offs which exist between sound emission, transmission and detection, as well as directional hearing under specific ecological settings. The mismatched filter situation may ultimately explain the maintenance of considerable variation in the carrier frequency of the male signal despite stabilizing selection.

1 aKostarakos, Konstantinos1 aHartbauer, Manfred1 aRömer, Heiner1 aTregenza, Tom uhttps://dx.plos.org/10.1371/journal.pone.000300502062nas a2200205 4500008004100000022001400041245013900055210006900194260001600263300001400279490000800293520137200301653002401673653001201697653002101709653002101730653002101751100002901772856005501801 2018 eng d a0340-759400aEvolutionarily conserved coding properties favour the neuronal representation of heterospecific signals of a sympatric katydid species0 aEvolutionarily conserved coding properties favour the neuronal r cJan-10-2018 a859 - 8720 v2043 a

To function as a mechanism in premating isolation, the divergent and species-specific calling songs of acoustic insects must be reliably processed by the afferent auditory pathway of receivers. Here, we analysed the responses of interneurons in a katydid species that uses long-lasting acoustic trills and compared these with previously reported data for homologous interneurons of a sympatric species that uses short chirps as acoustic signals. Some interneurons of the trilling species respond exclusively to the heterospecific chirp due to selective, low-frequency tuning and “novelty detection”. These properties have been considered as evolutionary adaptations in the sensory system of the chirper, which allow it to detect signals effectively during the simultaneous calling of the sympatric sibling species. We propose that these two mechanisms, shared by the interneurons of both species, did not evolve in the chirper to guarantee its ability to detect the chirp under masking conditions. Instead we suggest that chirpers evolved an additional, 2-kHz component in their song and exploited pre-existing neuronal properties for detecting their song under masking noise. The failure of some interneurons to respond to the conspecific song in trillers does not prevent intraspecific communication, as other interneurons respond to the trill.

10aAuditory processing10ainsects10aSelective coding10asignal detection10asignal evolution1 aKostarakos, Konstantinos uhttp://link.springer.com/10.1007/s00359-018-1282-0