https://popups.lib.uliege.be/2984-0317/index.php?id=524 Entrées d’index fr 0 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 https://popups.lib.uliege.be/2984-0317/index.php?id=521 Monogamy is very rare in mammals but frequent in birds. That is why the author proposes to investigate more closely some mating structures in birds, a zoological class in which monogamy is predominant. Having shown that modern ethologists emphasize individual strategies and gene based selection rather than group selection, having shown some important differences between polygamous and monogamous birds as sexual dimorphism and differencies in mate choice, the author studies the two mechanisms which allow male birds to be sure of their fatherhood : mate guarding of the fecond female and frequent copulations. Based on some recent publications, and particularly the most detailed study of the dunnock by Nick Davies, the demonstration shows that male and female reproductive strategies are not the same, and that speaking of a conflict between the sexes is unavoidable. The mutual recognition of the necessity of reproduction and the conflict about the divergent individual strategies in order to attain an optimal reproduction are the basis of a continuum among family structures. This continuum includes a spectrum of mating patterns from simultaneous polygyny to simultaneous polyandry. To look on human family organizations as structures of a continuum could lead to a better understanding of the reality we observe. Given the frequent convergencies of avian and human mating behaviour and family structures, it seems plausible that the socioethology of birds could contribute to an outline of human nature. L'éthologie lorenzienne a dressé le tableau d'un comportement animal qui, rétrospectivement, frappe par une certaine idéalisation de l'animal. Depuis les années septante, sous l'impact de la sociobiologie surtout, toute la biologie évolutionniste a rejeté la thèse de la sélection de groupe et l'idée que le comportement animal viserait l'intérêt de l'espèce. L'accent a été mis sur les stratégies de survie et de reproduction individuelles, voire sur les gènes, ce qui a eu un effet de désillusion. Il s'avère, en effet, que, même dans la monogamie, les tactiques reproductives mâles et femelles ne se recouvrent pas aussi parfaitement qu'on le pensait, d'où un conflit entre les sexes plus ou moins prononcé. Comme la plupart des humains vivent en famille biparentale, cette structure sociale mérite un intérêt tout particulier. Mais la monogamie est rare chez les mammifères. Pourquoi alors ne pas regarder de plus près une classe zoologique dans laquelle la monogamie constitue l'organisation sociale de base ? Est-ce que l'étude des oiseaux nous permet de mieux comprendre notre monogamie humaine, et ceci malgré la spécificité de cette dernière ? L'étude de différentes espèces d'oiseaux dont les stratégies de reproduction sont bien connues fait apparaître la monogamie comme un compromis acceptable pour les deux sexes si ces derniers n'arrivent pas à imposer l'organisation familiale qui leur assure le meilleur succès reproductif. Ce que l'on observe dans la réalité, c'est un continuum d'organisations, allant de la polygynie simultanée d'un côté, à la polyandrie simultanée de l'autre. Aussi bien les différents types de parades que les critères du choix du partenaire présentent des convergences avec des comportements humains. Il en va de même pour les efforts déployés par les mâles pour garantir leur certitude de paternité. Vu l'intérêt des nombreuses convergences entre les structures sociales des oiseaux et les nôtres, il semblerait que la socio-éthologie comparée des oiseaux apporterait une contribution valable à une esquisse de [a nature sociale de l'Homme. Dans ce contexte, l'élaboration de modèles qui expliquent les seuils de passage d'une structure à une autre est particulièrement souhaitable et prometteuse. Fri, 26 Jan 2024 13:31:19 +0100 Fri, 26 Jan 2024 13:31:46 +0100 https://popups.lib.uliege.be/2984-0317/index.php?id=521