Evolution of directional hearing in moths via conversion of bat detection devices to asymmetric pressure gradient receivers

Small animals typically localize sound sources by means of complex internal connections and baffles that effectively increase time or intensity differences between the 2 ears. But some miniature acoustic species achieve directional hearing without such devices, indicating that other mechanisms have evolved. Using 3D laser vibrometry to measure tympanum deflection, we show that female lesser waxmoths (Achroia grisella) can orient toward the 100-kHz male song because each ear functions independently as an asymmetric pressure gradient receiver that responds sharply to high-frequency sound arriving from an azimuth angle 30° contralateral to the animal's midline. We found that females presented with a song stimulus while running on a locomotion compensation sphere follow a trajectory 20° - 40° to the left or right of the stimulus heading but not directly toward it, movement consistent with the tympanum deflections and suggestive of a monaural mechanism of auditory tracking. Moreover, females losing their track typically regain it by auditory scanning – sudden, wide deviations in their heading – and females initially facing away from the stimulus quickly change their general heading toward it, orientation indicating superior ability to resolve the front-rear ambiguity in source location. X-ray CT scans of the moths did not reveal any internal coupling between the 2 ears, confirming for the first time that an acoustic insect can localize a sound source based solely on the distinct features of each ear

Impact of anthropogenic noise on the survival and development of meagre (Argyrosomus regius) early life stages

The growth of human populations has been driving an unprecedent and widespread increase in marine traffic, posing a real threat to marine biodiversity. Even though we are now aware of the negative effects of shipping noise exposure on fish, information about the impact on their early life stages continues to lack. Meagre (Argyrosomus regius) is a vocal fish that uses estuaries with high levels of anthropogenic noise pollution as both breeding areas and nurseries. Here, the effects of boat noise exposure on the development and survival of meagre larvae were studied. Embryos and larvae were exposed to either noise (boat noise playback) or control treatments (coils producing a similar electric field to the speakers) and hatching rate, survival rate, morphometric traits and stress-related biomarkers, at hatching and at 2 days-post-hatching (dph) were analyzed. Results showed no conclusive effects of the impact of boat noise playback, even though there was an increased lipid droplet consumption and a decrease in body depth at 2dph larvae under this stressor. The assessment of oxidative stress and energy metabolism-related biomarkers at hatching showed a marginal decrease in superoxide dismutase (SOD) activity and no changes in DNA damage or electron transport system activity (ETS), although it cannot be disregarded that those effects could only be visible at later stages of larval development. Whether these morphological and developmental results have implications in later stages remains to be investigated. Further studies with longer exposure and wild meagre could help deepen this knowledge and provide a better understanding of how anthropogenic noise can impact meagre early stagesFundação para a Ciência e Tecnologia - FCTinfo:eu-repo/semantics/publishedVersio

Potentialité de la bioacoustique comme outil de dénombrement d'espèces difficiles d'accès : cas du Lagopède alpin (Lagopus muta)

Population censuses of male rock ptarmigans (Lagopus muta) are conducted by point count protocol in spring (late May - early June). Several observers are placed at given points within the area and spend an hour listening to singing males to try to deduce an estimate of their number. The counting conditions are diffcult and cast doubt on the good representativeness of this protocol.The first objective of this thesis was to quantify the counting biases. The thesis then focused on finding ways to develop new counting methods to compensate for the biases of traditional counting. The acoustic signals emitted by animals carry several levels of information, such as the identity of the transmitter. The second part of my thesis showed that bioacoustic techniques based on acoustic differences in vocalizations were suitable to ptarmigan and that it was possible to determine the number of males in an area using the sounds they produce. The third part of the thesis is a generalization of the method on longterm recordings under real field conditions. It was not only possible to obtain the number of males but also the time of presence of each male and to assess his reproductive status.In conclusion, I showed the interest of the bioacoustic tool to monitor ptarmigan’s populations. My thesis opens up perspectives for futur large scale temporal and spatial monitoring of ptarmigan’s populations.Les recensements de populations de lagopèdes alpin (Lagopus muta) mâles se font par points d’écoute au printemps (fin mai – début juin). Plusieurs observateurs se placent à des points donnés au sein de la zone à recenser et passent une heure à écouter les mâles chanteurs pour essayer d’en déduire une estimation. Les conditions de comptages sont difficiles et font douter de la bonne représentativité de ce protocole. Le premier objectif de la thèse a été de quantifier les biais du comptage. La thèse s’est donc ensuite attachée à trouver des pistes pour développer de nouvelles méthodes de comptages pour compenser les biais du comptage traditionnel. Les signaux acoustiques émis par les animaux portent plusieurs niveaux d’informations, tel que l’identité de l’émetteur. La deuxième partie de ma thèse a montré que les techniques de bioacoustique basées sur les différences acoustiques des vocalisations étaient applicables au lagopède et qu’il était ainsi possible de déterminer le nombre de mâles dans une zone à l’aide des sons qu’ils produisent. La troisième partie de la thèse est une généralisation de la méthode sur des enregistrements à long terme en conditions de terrains réelles.Il a été non seulement possible d’obtenir le nombre de mâles mais également le temps de présence de chaque mâle et d’y relier son statut reproducteur. En conclusion, j’ai montré l’intérêt de l’outil bioacoustique comme outils de suivi des populations de lagopèdes alpins. Ma thèse ouvre des perspectives futures pour un suivi à larges échelles temporelles et spatiales des populations de lagopèdes

Bioacoustics potential as a tool for counting diffcult-to-access species : The case of the rock ptarmigan (Lagopus muta)

Les recensements de populations de lagopèdes alpin (Lagopus muta) mâles se font par points d’écoute au printemps (fin mai – début juin). Plusieurs observateurs se placent à des points donnés au sein de la zone à recenser et passent une heure à écouter les mâles chanteurs pour essayer d’en déduire une estimation. Les conditions de comptages sont difficiles et font douter de la bonne représentativité de ce protocole. Le premier objectif de la thèse a été de quantifier les biais du comptage. La thèse s’est donc ensuite attachée à trouver des pistes pour développer de nouvelles méthodes de comptages pour compenser les biais du comptage traditionnel. Les signaux acoustiques émis par les animaux portent plusieurs niveaux d’informations, tel que l’identité de l’émetteur. La deuxième partie de ma thèse a montré que les techniques de bioacoustique basées sur les différences acoustiques des vocalisations étaient applicables au lagopède et qu’il était ainsi possible de déterminer le nombre de mâles dans une zone à l’aide des sons qu’ils produisent. La troisième partie de la thèse est une généralisation de la méthode sur des enregistrements à long terme en conditions de terrains réelles.Il a été non seulement possible d’obtenir le nombre de mâles mais également le temps de présence de chaque mâle et d’y relier son statut reproducteur. En conclusion, j’ai montré l’intérêt de l’outil bioacoustique comme outils de suivi des populations de lagopèdes alpins. Ma thèse ouvre des perspectives futures pour un suivi à larges échelles temporelles et spatiales des populations de lagopèdes.Population censuses of male rock ptarmigans (Lagopus muta) are conducted by point count protocol in spring (late May - early June). Several observers are placed at given points within the area and spend an hour listening to singing males to try to deduce an estimate of their number. The counting conditions are diffcult and cast doubt on the good representativeness of this protocol.The first objective of this thesis was to quantify the counting biases. The thesis then focused on finding ways to develop new counting methods to compensate for the biases of traditional counting. The acoustic signals emitted by animals carry several levels of information, such as the identity of the transmitter. The second part of my thesis showed that bioacoustic techniques based on acoustic differences in vocalizations were suitable to ptarmigan and that it was possible to determine the number of males in an area using the sounds they produce. The third part of the thesis is a generalization of the method on longterm recordings under real field conditions. It was not only possible to obtain the number of males but also the time of presence of each male and to assess his reproductive status.In conclusion, I showed the interest of the bioacoustic tool to monitor ptarmigan’s populations. My thesis opens up perspectives for futur large scale temporal and spatial monitoring of ptarmigan’s populations

Evolution of synchronies in insect choruses

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Espace acoustique perceptif des bruits de pneus

Le bruit du trafic routier représente la part majoritaire du bruit environnemental urbain perçu et a d’importantes conséquences sur la santé. Les bruit de roulement des pneus des véhicules contribue grandement aux sons routiers perçus. Les sculptures des pneus de véhicules légers sont déjà conçues pour minimiser les bruits émis depuis une dizaine d'années. Ce n’est pas encore le cas des poids lourds. Le projet européen LEON-T a pour but de minimiser les nuisances des pneumatiques de poids lourds, notamment sonore. En préalable à une étude des effets du bruit de pneumatique sur le sommeil, une expérience a été menée pour déterminer les paramètres du timbre de tels bruits. Le jeu de données utilisés a été obtenu par une série d'enregistrements sur une piste normalisée en utilisant des pneus de tailles variées. Ces stimuli ont été présentés au casque, dans une tâche de tri libre. La présentation montrera les résultats de cette expérience, notamment les corrélations entre paramètres acoustiques et structure de l'espace perceptif déterminés à partir des groupes formés par les participants

Phylogeographic structure without pre-mating barriers: Do habitat fragmentation and low mobility preserve song and chorus diversity in a European bushcricket?

International audienc

Group synchrony and alternation as an emergent property:elaborate chorus structure in a bushcricket is an incidentalby-product of female preference for leading calls: Group synchrony and alternation as an emergent property: elaborate chorus structure in a bushcricket is an incidental by-product of female preference for leading calls

International audienceMany acoustic animals exhibit temporally structuredchorusing, and in some cases, groups of calling malesdisplay elaborate forms of synchrony and/or alternation. Suchtemporal structure has traditionally been explained as an adaptationby which chorusing males preserve critical call features,maximize the attractiveness of their local group to females,or improve their ability to detect, evaluate, and/orevade rival males or predators. However, an alternative possibilityis that synchrony and alternation simply emerge as incidentalby-products of basic pairwise signal interactions betweenmale neighbors. Thus, females may not be influencedby synchrony and alternation, and males may not benefit perse from the very chorus that they collectively produce. Westudied chorusing in the bushcricket Ephippiger diurnus, aspecies that sings in both synchrony and alternation, by presentingnatural and modified chorus stimuli to females in aseries of playback tests. We found that females respondedreadily to the various stimuli, but we did not observe an elevatedresponse to the natural chorus stimuli in any experimentor in any of the several E. diurnus populations tested. Ourresults demonstrate for the first time how elaborate forms ofsynchrony and alternation can represent emergent propertiesof choruses as opposed to specialized group displays that affordparticular advantages to the individual singers

Evolution of communication signals and information during species radiation

Communicating species identity is a key component of many animal signals. However, whether selection for species recognition systematically increases signal diversity during clade radiation remains debated. Here we show that in woodpecker drumming, a rhythmic signal used during mating and territorial defense, the amount of species identity information encoded remained stable during woodpeckers’ radiation. Acoustic analyses and evolutionary reconstructions show interchange among six main drumming types despite strong phylogenetic contingencies, suggesting evolutionary tinkering of drumming structure within a constrained acoustic space. Playback experiments and quantification of species discriminability demonstrate sufficient signal differentiation to support species recognition in local communities. Finally, we only find character displacement in the rare cases where sympatric species are also closely related. Overall, our results illustrate how historical contingencies and ecological interactions can promote conservatism in signals during a clade radiation without impairing the effectiveness of information transfer relevant to inter-specific discrimination

Age-related changes in intra-sexual interactions in the black redstart Phoenicurus ochruros

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