Innate releasing mechanisms and fixed action patterns: basic ethological concepts as drivers for neuroethological studies on acoustic communication in Orthoptera

Abstract

This review addresses the history of neuroethological studies on acoustic communication in insects. One objective is to reveal how basic ethological concepts developed in the 1930s, such as innate releasing mechanisms and fixed action patterns, have influenced the experimental and theoretical approaches to studying acoustic communication systems in Orthopteran insects. The idea of innateness of behaviors has directly fostered the search for central pattern generators that govern the stridulation patterns of crickets, katydids or grasshoppers. A central question pervading 50 years of research is how the essential match between signal features and receiver characteristics has evolved and is maintained during evolution. As in other disciplines, the tight interplay between technological developments and experimental and theoretical advances becomes evident throughout this review. While early neuroethological studies focused primarily on proximate questions such as the implementation of feature detectors or central pattern generators, later the interest shifted more towards ultimate questions. Orthoptera offer the advantage that both proximate and ultimate questions can be tackled in the same system. An important advance was the transition from laboratory studies under well-defined acoustic conditions to field studies that allowed to measure costs and benefits of acoustic signaling as well as constraints on song evolution.

Modular timer networks: abdominal interneurons controlling the chirp and pulse pattern in a cricket calling song

“…The elaborate acoustic and/or vibratory signals of drosophilids (Mazzoni et al 2013 ; Herrnández and Fabre 2016 ), hemiptera such as cicadas and bugs (Claridge 1985 ; Fonseca 1991 ; Virant-Doberlet and Cokl 2004 ), and orthopteran insects such as acridid grasshoppers (Otte 1970 ; Bull 1979 ; Vedenina and von Helversen 2003 ) and crickets (Alexander 1962 ; Otte 1992 ) are crucial for species-specific recognition during mating behaviour. Their evolution has been shaped by sexual selection (Zahavi 1980 ; Huber and Gerhardt 2002 ; Ronacher 2019 ) to produce reliable and species-specific communication signals, which can be stereotypic signal sequences like in a Morse code. The timing of the signalling events is crucial for the receiver’s recognition process (Hennig et al 2014 ).…”

Reticulate Evolutionary History in a Recent Radiation of Montane Grasshoppers Revealed by Genomic Data

“…3 and Supplementary Tables S1-4 available on Dryad). Forewings are involved in courtship acoustic behavior in grasshoppers (Von Helversen et al 2004; Vedenina and Mugue 2011; Ronacher 2019), a character directly implicated in mate attraction and subjected to sexual selection (Oh and Shaw 2013; Outomuro et al 2016). Traits under sexual selection can evolve rapidly, accelerating speciation when other forces as ecological adaptations are not so evident or absent (Anderson 1994; Mendelson and Shaw 2005; Rundell and Price 2009).…”

Neurophysiology goes wild: from exploring sensory coding in sound proof rooms to natural environments

“…Thus, neurophysiological studies and neural network models (Phelps 2007 ) have strongly contributed to our understanding of hidden preferences in receivers and the preferences they express in behavioural trials, although the preferences for acoustic signals can be examined without any knowledge of the underlying sensory system. Similarly, the different behavioural paradigms applied in studies of grasshoppers, crickets, and katydids have shown that the innate releasing mechanism for species recognition is based primarily on the temporal pattern of songs (von Helversen 1972 ; Stumpner and von Helversen 2001 ; Gerhardt and Huber 2002 ; Hennig et al 2004 ; Ronacher 2019 ). The search for the underlying neuronal network of the innate releasing mechanism in crickets has been long and difficult.…”

“…The search for the underlying neuronal network of the innate releasing mechanism in crickets has been long and difficult. During this time, a shift in the different concepts has been observed (reviewed in Ronacher 2019 ). Still, the picture that is currently emerging (Kostarakos and Hedwig 2015 ; Schöneich et al 2015 ; Hedwig 2016 ) classically illustrates the fruitful interaction between behaviour and physiology in the field of neuroethology.…”