![]() ![]() La compétition inter-espèces, et les spécialisations de niche qui en découlent, semblent être un facteur évolutif clé de leurs répertoires. ![]() Nous avons d'abord abordé cette question chez deux cercopithèques sympatriques, le singe Diane et la mone de Campbell. Des approches intégratives comparant des espèces phylogénétiquement proches, et mettant en évidence la relation possible entre les caractéristiques de leurs systèmes sociaux, leurs niches écologiques et les systèmes de communication vocale associés, sont nécessaires pour approfondir notre compréhension de ce puzzle évolutif. Cependant, les mesures utilisées classiquement pour aborder cette question (c'est-à-dire le nombre de types de cris et la taille du groupe) ne permettent pas de comprendre toutes les subtilités de l'évolution des systèmes de communication. L'hypothèse selon laquelle vivre dans un système social complexe nécessite des capacités de communication complexes a gagné du terrain. Au-delà de l'habitat, la vie sociale constitue probablement une importante pression de sélection. Il ne fait aucun doute que différents facteurs déterminent la trajectoire évolutive des capacités de communication d'une espèce. Even if primate vocal repertoires change slowly over evolutionary time, making them good phylogenetic indicators, socio-ecological niches may induce considerable local divergence at different levels: vocal repertoire composition, acoustic structure and contextual use of calls, and vocal interaction patterns. Vocal turn-taking predominated in the most tolerant species (bonobo and gorilla). ![]() Chimpanzee, the most competitive species displayed a high proportion of overlapping vocalisations. Orang-utan, the most solitary species, preferentially used repeated and isolated calls apparently outside of any vocal interactions. However, close call interaction patterns differed in line with the nature of societies. We found no relationship between classical social (group size, interaction rates) and vocal (repertoire size, call rates) complexity metrics. Lastly, because the core of communication is represented not only by what is expressed by an isolated caller, but also by the way vocal interactions are structured, we explored ‘conversational rules’ in apes. We found that tolerant (Tonkean and crested) macaques displayed higher levels of vocal diversity (number of vocal units) and flexibility (degree of gradation) than intolerant (Japanese and rhesus) macaques in agonistic and affiliative (but not neutral) contexts. Secondly, we compared the acoustic structures in macaques belonging to four species with contrasting social styles. This was linked to differences in group size and degree of exposition to predators. While most of their vocal units were shared, we found a diversification of alarm calls and socially meaningful vocal combinations, as well as a differential use of inconspicuous (less detectable) call structures. Interspecies competition, and the niche specialisations this creates, appeared to be a key evolutionary driver of their repertoires. We first addressed this topic in two sympatric guenons, Diana monkeys and Campbell’s monkeys. Integrative approaches comparing closely related species to highlight the possible relationship between the characteristics of their social systems, their ecological niche and associated vocal communication systems are required to further our understanding of this evolutionary puzzle. ![]() number of call types and group size) fail to capture some of the subtleties of the evolution of communication systems. However, the measures used classically to tackle this question (i.e. The hypothesis positing that living in a complex social system requires complex communication skills has gained ground. Beyond habitat, social life is likely a selection pressure. There is no doubt that different factors determine the evolutionary trajectory of a species' communication abilities. ![]()
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