Substrate-borne vibrations used during acoustic communication and the existence of courtship songs in some species of the genus Anaxipha (Saussure) (Orthoptera: Trigonidiidae: Trigonidiinae)

Anaxipha (Saussure, 1874) are small, swordtail crickets found in much of eastern North America. Many species within the genus Anaxipha were only recently described and their calling songs characterized. However, little is known about their courtship songs or use of substrate-borne communication (drumming). This study is the first documentation of the existence of courtship songs and substrate-borne vibrational communication in the genus. Courtship songs and substrate-borne vibrational communication were first detected in the following species: Anaxipha exigua (Say, 1825), A. tinnulacita Walker & Funk, 2014, A. tinnulenta Walker & Funk, 2014, and A. thomasi Walker & Funk, 2014. When in the presence of a conspecific female, males of all four species perform courtship songs that are distinctly different in pattern of echeme delivery and syllable details compared to their respective calling songs. Additionally, males of all four species exhibited drumming behavior during courtship singing and variably during calling songs. Examination of video recordings of males drumming during courtship singing showed that they are apparently using the sclerotized portion of their mandibles to impact the substrate on which they are perched to create vibrations. Courtship song and drumming bout characteristics were statistically different among the four species studied here, although A. tinnulacita and A. tinnulenta were similar in some measurements. Drumming during calling songs was common only in A. tinnulacita, where drumming occurs predominately during the first forty percent and last twenty percent of the long echemes of calling songs. Additional study is needed to further explore the use of substrate-borne vibrational communication in this genus.

Songs and morphology in three species of the Chorthippus biguttulus group (Orthoptera, Acrididae, Gomphocerinae) in Russia and adjacent countries

Songs and morphology are compared between Chorthippus miramae (Vorontsovsky, 1928) that was previously named as C. porphyropterus and two other closely related species, C. brunneus (Thunberg, 1815) and C. maritimus Mistshenko, 1951. We compare them because the calling song of C. miramae was previously shown to have song elements similar to those of other two species. One morphological character, the length of stridulatory file, appeared to be the best character to distinguish between all three species. For C. maritimus and C. miramae, we present the morphological descriptions since they are absent in the literature. We also establish the synonymy C. maritimus = C. bornhalmi Harz, 1971, syn. n. = C. biguttulus eximius Mistshenko, 1951, syn. n. In the song analysis, we analyse not only the sound but also the leg-movement pattern, which is very helpful to find a homology between various song elements. We show that the calling song of C. miramae usually contains two elements, one element being similar to the C. brunneus calling song, and another – to the C. maritimus calling song. Despite some similarities, the calling song elements in C. miramae have some peculiarities. The courtship song of C. miramae is similar to the C. brunneus song, whereas the rivalry songs of C. miramae comprise both the maritimus-like elements and the unique ones. C. miramae generally demonstrates a richer song repertoire than the other two species.

Quadratic and adaptive computations yield an efficient representation of song in Drosophila auditory receptor neurons

Sensory neurons encode information using multiple nonlinear and dynamical transformations. For instance, auditory receptor neurons in Drosophila adapt to the mean and the intensity of the stimulus, change their frequency tuning with sound intensity, and employ a quadratic nonlinearity. While these computations are considered advantageous in isolation, their combination can lead to a highly ambiguous and complex code that is hard to decode. Combining electrophysiological recordings and computational modelling, we investigate how the different computations found in auditory receptor neurons in Drosophila combine to encode behaviorally-relevant acoustic signals like the courtship song. The computational model consists of a quadratic filter followed by a divisive normalization stage and reproduces population neural responses to artificial and natural sounds. For general classes of sounds, like band-limited noise, the representation resulting from these highly nonlinear computations is highly ambiguous and does not allow for a recovery of information about the frequency content and amplitude pattern. However, for courtship song, the code is simple and efficient: The quadratic filter improves the representation of the song envelope while preserving information about the song's fine structure across intensities. Divisive normalization renders the presentation of the song envelope robust to the relatively slow fluctuations in intensity that arise during social interactions, while preserving information about the species-specific fast fluctuations of the envelope. Overall, we demonstrate how a sensory system can benefit from adaptive and nonlinear computations while minimizing concomitant costs arising from ambiguity and complexity of readouts by adapting the code for behaviorally-relevant signals.

Male courtship song drives escape responses that are suppressed for successful mating

Persuasion is a crucial component of the courtship ritual needed to overcome contact aversion. In fruit flies, it is well established that the male courtship song prompts receptivity in female flies, in part by causing sexually mature females to slow down and pause, allowing copulation. Whether the above receptivity behaviours require the suppression of contact avoidance or escape remains unknown. Here we show, through genetic manipulation of neurons we identified as required for female receptivity, that male song induces avoidance/escape responses that are suppressed in wild type flies. First, we show that silencing 70A09 neurons leads to an increase in escape, as females increase their walking speed during courtship together with an increase in jumping and a reduction in pausing. The increase in escape response is specific to courtship, as escape to a looming threat is not intensified. Activation of 70A09 neurons leads to pausing, confirming the role of these neurons in escape modulation. Finally, we show that the escape displays by the female result from the presence of a courting male and more specifically from the song produced by a courting male. Our results suggest that courtship song has a dual role, promoting both escape and pause in females and that escape is suppressed by the activity of 70A09 neurons, allowing mating to occur.

Fast and accurate annotation of acoustic signals with deep neural networks

Acoustic signals serve communication within and across species throughout the animal kingdom. Studying the genetics, evolution, and neurobiology of acoustic communication requires annotating acoustic signals: segmenting and identifying individual acoustic elements like syllables or sound pulses. To be useful, annotations need to be accurate, robust to noise, fast. We introduce DeepSS, a method that annotates acoustic signals across species based on a deep-learning derived hierarchical presentation of sound. We demonstrate the accuracy, robustness, and speed of DeepSS using acoustic signals with diverse characteristics: courtship song from flies, ultrasonic vocalizations of mice, and syllables with complex spectrotemporal structure from birds. DeepSS comes with a graphical user interface for annotating song, training the network, and for generating and proofreading annotations (available at https://janclemenslab.org/deepss). The method can be trained to annotate signals from new species with little manual annotation and can be combined with unsupervised methods to discover novel signal types. DeepSS annotates song with high throughput and low latency, allowing realtime annotations for closed-loop experimental interventions.

Contributions to the study of the grasshopper (Orthoptera: Acrididae: Gomphocerinae) courtship songs from Kazakhstan and adjacent territories

Male courtship songs of 9 grasshopper species of Gomphocerinae from Kazakhstan and Orenburg region and Altai Republic of Russia were studied. We analyzed not only the sound, but also the stridulatory movements of the hind legs to more entirely describe the songs. We also analyze the frequency spectra of the songs and the whole visual display during courtship. The courtship songs of three species, Stenobothrus miramae, Chorthippus dubius and Ch. angulatus, were studied for the first time. In four species, Omocestus haemorrhoidalis, O. petraeus, Myrmeleotettix pallidus, Ch.karelini, we found certain differences in temporal pattern of the courtship songs in comparison with the previous data on the respective species from other regions. In five species, O. viridulus, S. miramae, M. pallidus, Ch. dubius and Ch. karelini, various parts of elaborate courtship songs differed in the carrier frequency. In four species, O. haemorrhoidalis, O. petraeus, M. pallidus and Ch. dubius, the dominant frequencies of the courtship song were shown to lie in the range higher than 20 kHz. The conspicuous movements of antennae and legs during courtship were studied in M. pallidus, S. miramae and Gomphocerus sibiricus.

Neural Network Organization for Courtship Song Feature Detection in Drosophila

ABSTRACTAnimals communicate using sounds in a wide range of contexts, and auditory systems must encode behaviorally relevant acoustic features to drive appropriate reactions. How feature detection emerges along auditory pathways has been difficult to solve due to both challenges in comprehensively mapping the underlying circuits, particularly in large brains, and in characterizing tuning for behaviorally relevant features. Here, we take advantage of the small size, genetic tools, and connectomic resources for the Drosophila melanogaster brain to investigate feature selectivity for the two main modes of fly courtship song, sinusoids and pulse trains. By building a large collection of genetic enhancer lines, we identify 24 new cell types of the intermediate layers of the auditory pathway. Using a new connectomic resource, FlyWire, we map connections among these cell types, in addition to connections to known early and higher-order auditory neurons. We characterize auditory responses throughout this pathway, and find that the newly discovered neurons show diverse preferences for courtship song modes. However, rather than being sorted into separate streams, neurons with different preferences are highly interconnected. Among this population, frequency tuning is centered on frequencies present in song, whereas rate tuning is biased towards rates below those present in song, suggesting that these neurons form a basis set for the generation of pulse feature tuning downstream. Our study provides new insights into the organization of auditory coding within the Drosophila brain.