Meeting Abstract
The Pomacanthidae is an iconic reef fish family of about 88 species. They occupy a diverse range of trophic niches (e.g. spongivory, algivory, zooplanktivory) and show habitat partitioning (e.g. cryptic, pelagic species). The pomacanthids reach disparate body form, with large body sized species (e.g. 30-45 cm of Total Length – Pomacanthus spp) and a paraphyletic group of 34 pygmy angelfishes (e.g. 7-12 cm TL – Centropyge spp). To the best of our knowledge, the hypothesis that size variation in Pomacanthidae is adaptive and the potential correlation between size and overall body shape optima has never been tested in a quantitative evolutionary framework. Here, we tested these hypotheses using a novel time-calibrated phylogeny, eco-morphological data and phylogenetic comparative methods. The method SURFACE allowed the detection of three adaptive peaks in the body size space, one of them referring directly to the pygmy angelfishes (θpygmy = 11 cm TL). Firstly, we found no evidence of evolutionary allometry across angelfishes (PGLS analysis; P-value = 0.12). Secondly, in order to detect the major driving force of overall body shape in angelfishes, we compared the fit of Brownian motion (BM) and Ornstein-Uhlenbeck (OU) models that allow for different optimal shapes according to size, diet and habitat partitioning. Counter to our simple prediction of size and ecological determinants of body shape, a single-optimum OU model produced the best fit. Overall, our results show that the drivers of size diversity may differ from the ones of body shape.
