Abstract :
[en] The Pomacentridae family, or damselfishes, includes more than 330 species living mainly in a coral reef environment. They have a complex life cycle involving a pelagic dispersion period of larvae and a juvenile and adult benthic life period associated to reef. The colonisation is associated with a metamorphosis allowing the fish to adapt to their new environment. Our study focused on morphological modifications, as skeletal shape changes, occurring during the development from settling larvae to juvenile and leading to diversification of adult species.
To test allometry and to examine diversification in shapes, geometric morphometrics were used. This method, which allows description and statistical analysis of form, is applied to define ontogenetic shape changes and to compare allometries responsible for species diversification. It is applied here for skull structures involved in food capture as neurocranium, suspensorium, opercle, premaxillary bone and mandible. Six species were studied: Chromis viridis, Dascyllus aruanus, Dascyllus carneus, Pomacentrus pavo, Chrysiptera glauca and Stegastes nigricans.
At the end of larval stage, structures in fishes are rather similar. None of the species has an isometric growth. Ontogenetic allometries concern each skeletal unit. The two species of Dascyllus are the lone to have a common ontogenetic transformation, and it appears that allometries giving the shapes’diversification correspond to ecological adaptations of each species. From a functional point of view, the general trend in skeletal shape changes corresponds to an optimisation of the suction feeding apparatus (for example: development in height and length of the suspensorium and opercle, shortening of the mandible).
