Interspecific variation of warning calls in piranhas: a comparative analysis

Fish sounds are known to be species-specific, possessing unique temporal and spectral features. We have recorded and compared sounds in eight piranha species to evaluate the potential role of acoustic communication as a driving force in clade diversification. All piranha species showed the same kind of sound-producing mechanism: sonic muscles originate on vertebrae and attach to a tendon surrounding the bladder ventrally. Contractions of the sound-producing muscles force swimbladder vibration and dictate the fundamental frequency. It results the calling features of the eight piranha species logically share many common characteristics. In all the species, the calls are harmonic sounds composed of multiple continuous cycles. However, the sounds of Serrasalmus elongatus (higher number of cycles and high fundamental frequency) and S. manueli (long cycle periods and low fundamental frequency) are clearly distinguishable from the other species. The sonic mechanism being largely conserved throughout piranha evolution, acoustic communication can hardly be considered as the main driving force in the diversification process. However, sounds of some species are clearly distinguishable despite the short space for variations supporting the need for specific communication. Behavioural studies are needed to clearly understand the eventual role of the calls during spawning events

Interspecific variation of warning calls in piranhas: comparative analysis

Fish sounds are often considered as species-specific with unique temporal and spectral features. Differences between acoustic signals of closely related species could be considered as pre-zygotic barrier and could be related to the evolutionary history of the species. In the present study, sounds were recorded and compared in eight piranha species (Serrasalmus elongatus, Serrasalmus marginatus, Serrasalmus compressus, Serrasalmus manueli, Serrasalmus spilopleura, Serrasalmus rhombeus, Serrasalmus eigenmanni and Pygocentrus nattereri) in order to evaluate the potential role of acoustic communication as a driving force in the clade diversification. The same kind of sound-producing mechanism was found in all the species: sonic muscles originate on vertebrae and attach to a tendon surrounding ventrally the bladder. Contractions of the sound-producing muscles force swimbladder vibration. Having the same kind of sound-producing mechanism, the calling features of the eight piranha species show logically many common characteristics. In all the species, the calls are harmonic sounds composed of several pulses without inter-pulse interval. It was possible to discern species-specific sounds, but the differences among species could be, in part, explained by the size. Only the sounds of S. elongatus and S. manueli are really distinguishable from the other species. Serrasalmus elongatus differed by having a higher number of pulses and high-pitched fundamental frequency, whereas S. manueli differed by having long pulse periods and a low fundamental frequency. In the framework of this study, acoustic communication cannot be considered as the main driving force in the diversification process of piranhas. Behavioral studies are however needed to clearly understand the eventual role of the calls during the spawning events

Neurones histaminergiques et cycle veille-sommeil (approche expérimentale pluridisciplinaire chez les rongeurs)

Par l'étude des souris knockout (KO) sans synthèse d'histamine (HA), nous avons montré l'importance des neurones à HA dans les mécanismes permissifs du sommeil paradoxal, les aspects qualitatifs de l'éveil (Ev) et le maintien du cerveau en Ev face à des défis comportementaux, en plus de leur importance dans l'Ev spontané. L'étude des souris KO sans le récepteur H1 ou H2 a montré que le rôle clé joué par les neurones à HA est assuré largement par les récepteurs H1 et qu'une augmentation de la transmission cholinergique expliquerait un taux journalier d'éveil proche de la normale observable chez les souris KO H1. Les connexions entre les systèmes à HA et cholinergique ont été confirmées par une étude anatomique combinant l'hybridation in situ des ARNm des récepteurs histaminergiques et l'immunohistochimie dirigée contre le système cholinergique. L'ensemble de nos données montre l'importance des neurones à histamine et de leurs projections dans la régulation de l'éveil chez les rongeurs.LYON1-BU.Sciences (692662101) / SudocSudocFranceF

Working and Reference Memory Tasks Trigger Opposed Long-Term Synaptic Changes in the Rat Dentate Gyrus

International audienc

Birth and Evolution of Acoustic Communication in Piranhas (Serrasalmidae)

Within piranhas, sound production is known in carnivorous species whereas herbivorous species were thought to be mute. As these carnivorous sonic species have a complex sonic apparatus, we hypothesise that transitional forms could be found in some serrasalmid species. We investigate sound production in different species covering all the Serrasalmidae phylogenetic tree to understand the evolution of the sonic mechanism in this family. The results highlight the evolutionary transition from a simple sound-producing mechanism without specialised sonic structures in the herbivorous species (Piaractus and Myloplus) to a sonic mechanism involving large, fast-contracting sonic muscles vibrating the swimbladder in the genera Pygocentrus and Serrasalmus. Hypaxial muscles in herbivores primarily serve locomotion, but some bundles caused sound production during swimming accelerations, meaning these muscles have gained a dual function. Sound production therefore seems to have been acquired through an exaptation event, i.e. the development of a new function (sound production) in existing structures initially shaped for a different purpose (locomotion). In further evolutionary stages (Catoprion and Pygopristis), some bundles are distinguishable from other hypaxial muscles and insert directly on the swimbladder. At this stage, the primary function (locomotion) is lost in favour of the secondary function (sound production). In the last stage (Pygocentrus and Serrasalmus), the muscles and insertion sites are larger and the innervation involves more spinal nerves, improving calling abilities. The comparison of sounds and sonic mechanisms shows the evolution of acoustic communication corresponds to a trajectory where the initial exaptation event is then subject to adaptations

Evaluation of thermo-mechanical stresses of a power module dedicated to high temperature applications

HITEN 2005 - International Conference on High Temperature Electronics, Paris, FRANCE, 06-/09/2005 - 08/09/2005In avionic area, the trend is to a growing use of power electronics systems. In this context, we will present results concerning test vehicles (power modules) in order to improve a device assembly technology dedicated to be located on the engine, in harsh operating conditions with thermal cycling from -50°C to 200°C in the worst case. The paper focuses on failure modes observed under high operating temperature and high temperature cycles, especially ceramic cracks, conchoidal fracture under the copper lead-frame and solder crack initiation. Numerical thermo-mechanical simulations of the assembly allow to understand the origin of the failures and to improve the assembly lifetime under such severe operating conditions. The objectives of the study are to assess the lifetime behaviour of these modules towards both high temperature and thermal cycling effects

Electrical Characterizations and evaluation of thermo-mechanical stresses of a power module dedicated to high temperature applications

EPE 2005 - 11th European Conférence on Power Electronics and Applications, Dresde, ALLEMAGNE, 11-/09/2005 - 14/09/2005In avionic area, the trend is to a growing use of power electronics systems. In this context, we will present results concerning test vehicles (power modules) in order to improve a device assembly technology dedicated to be located on the engine, in harsh operating conditions with thermal cycling from -50°C to 200°C in the worst case. The paper focuses on failure modes observed under high operating temperature and high temperature cycles, especially ceramic cracks, conchoidal fracture under the copper lead-frame and solder crack initiation. Numerical thermo-mechanical simulations of the assembly allow to understand the origin of the failures and to improve the assembly lifetime under such severe operating conditions. The objectives of the study are to assess the lifetime behaviour of these modules towards both high temperature and thermal cycling effects

Evaluation of thermo-mechanical stresses of a power module dedicated to high temperature applications

HITEN 2005 - International Conference on High Temperature Electronics, Paris, FRANCE, 06-/09/2005 - 08/09/2005In avionic area, the trend is to a growing use of power electronics systems. In this context, we will present results concerning test vehicles (power modules) in order to improve a device assembly technology dedicated to be located on the engine, in harsh operating conditions with thermal cycling from -50°C to 200°C in the worst case. The paper focuses on failure modes observed under high operating temperature and high temperature cycles, especially ceramic cracks, conchoidal fracture under the copper lead-frame and solder crack initiation. Numerical thermo-mechanical simulations of the assembly allow to understand the origin of the failures and to improve the assembly lifetime under such severe operating conditions. The objectives of the study are to assess the lifetime behaviour of these modules towards both high temperature and thermal cycling effects