https://popups.lib.uliege.be/2984-0317/index.php?id=912 Publications de Auteurs Marc Y. Ylieff fr 0 https://popups.lib.uliege.be/2984-0317/index.php?id=1441 Cette recherche in situ consiste en une étude des comportements agressifs envers des mollusques gastéropodes chez le mâle territorial nidificateur de Symphodus ocellatus, comportements impliqués dans la défense du nid et des œufs. Quatre questions impliquant Symphodus ocellatus et des mollusques gastéropodes ont été examinées. Les questions concernaient : (1) le nettoyage sélectif du nid en fonction du danger potentiel de prédation des mollusques sur les oeufs, (2) la reconnaissance visuelle d'un mollusque naturel d'un leurre coloré artificiellement, (3) les capacités de discrimination des couleurs par le système visuel et, plus généralement (4) l'importance de l'investissement du mâle territorial dans la défense du nid, rôle qui assurerait le succès reproducteur de l'espèce. Nos observations et nos expérimentations (leurres colorés) permettent de conclure que chez Symphodus ocellatus, les mâles territoriaux nidificateurs nettoient constamment leur nid quelle que soit l'espèce de mollusque gastéropode introduite ; qu'ils ont une connaissance de leur environnement biologique habituel suffisante pour pouvoir discriminer un mollusque gastéropode d'un leurre ; que le canal perceptif utilisé pour la reconnaissance sociale est le canal visuel constitué d'un système neuronal capable de percevoir finement les couleurs, particularité qui supporte la théorie relative à l'importance d'une couleur spécifique (le rouge ici) pour la communication optique ; que la protection du frai apportée par le mâle territorial, tâche guidée par ses moyens visuels, est nécessaire face aux dangers que représentent certains mollusques gastéropodes partageant son habitat. This field research examines aggressive behaviour towards gasteropod molluscs in nesting territorial male of Symphodus ocellatus. This behaviour is useful for brood and nest defense. Four questions involving Symphodus ocellatus towards gasteropod molluscs were investigated. Questions of interest were : (1) selective cleaning of the nest according to possible predation of molluscs on the eggs, (2) visual recognition of natural mollusc from artificially coloured dummies, (3) colours discriminating abilities by the visual system and, more generally (4) the importance of territorial male investment in nest defence ; this role could ensure a successful reproduction of the species. Our observations and experimentations (coloured dummies) allow us to conclude that in Symphodus ocellatus, nesting territorial males clean every time their nest, any gasteropod mollusc species whatever ; that they have sufficient knowledge of their usual biological environment to be able to discriminate a gasteropod mollusc from a dummy ; that the organ of perception used for social recognition is the visual channel constituted by a neural system competent to perceive colours finely, a special quality which support the theory about the use of one specific colour (red for S. ocellalus) for visual communication ; that fry protection insured by territorial male, a task guided by his visual system, is necessary considering dangers from some gasteropod molluscs living in his habitat. Thu, 01 Feb 2024 16:14:38 +0100 Tue, 12 Mar 2024 16:37:17 +0100 https://popups.lib.uliege.be/2984-0317/index.php?id=1441 https://popups.lib.uliege.be/2984-0317/index.php?id=903 In contrast to tropical environments, Mediterranean fish assemblages have been exposed to greater seasonal fluctuations of climatic factors (water temperature, photoperiod), which have impacted more or less significantly on the biology of fish. The labrid fishes (wrasses) are good examples of how climatic changes influence behavioural strategies. The European wrasses differ mainly from the tropical ones by their particular reproductive behavioural patterns. In these wrasses, the variety of the reproductive strategies (hermaphroditism or gonochorism, spawning seasonality in open water or on substrates, degrees of parental care, etc.) make it possible to study the evolution of these srrategies. If in tropics, most of wrasses exhibit planktonic spawning, the Mediterranean ones adapted their behaviour, developing modes of reproduction unusual in the tropics : short periods of reproduction, spawning eggs on substrates or in elaborated nests, parental care. This evolution is dictated, in particular, by the pressure of climatic factors, such as water temperature, on the presence or the absence of parental care. Of the 21 Mediterranean species, almost all the species studied lay their eggs on substrates or in a nest built by the large territorial male. Only Coris julis, Thalassoma pavo and Xyrichthys novacula (protogynous hermaphroditism fish species) spawn in open water (planktonic spawning) as tropical species do. Moreover, the majority of Symphodus males have complex social structures where nesting territorial males, satellite and sneaker males can be recognized. These sneakers adopt reproductive behavioural patterns known as alternative reproductive behaviour. They can either steal the spawn (streaking) or steal the female (sneaking). Finally, the majority of these Symphodus give parental care throughout each nesting cycle (2 to 5 nests are elaborated during the reproductive season in spring), which always comprises three phases : nest building phase (construction with alive algae of a substrate for spawning or a true nest in form of cup), sexual activity phase (the very moment the females come to spawn in the nest), and fanning phase (oxygenation of eggs, by the beat of the pectoral fins, until hatching). The diversity of the biological and behavioural adaptations developed by numerous tropical and temperate species of labrid fishes allow us to consider the family as an ideal group to investigate various problems in behavioural ecology. Tue, 30 Jan 2024 16:03:56 +0100 Tue, 30 Jan 2024 16:04:04 +0100 https://popups.lib.uliege.be/2984-0317/index.php?id=903