Meeting Abstract
The ecomorphology of fish feeding is an intensely studied area of functional morphology and comparative biology. This body of work has identified jaw protrusion as an innovation that has promoted massive diversification in multiple lineages. Two of these, the Acanthomorpha and Cypriniformes, account for approximately one third of living vertebrates. We performed phylogenetic comparative analyses of jaw protrusion kinematics and cranial morphology in species-rich families from each clade and found jaw protrusion to have undergone extensive evolution in both. Alterations in protrusion ability were significantly related to shifts in feeding niche and protrusion performance is predominantly determined by upper jaw morphology, particularly the length of the ascending arm on the premaxilla, which is an anatomical structure that has evolved convergently in both lineages. To better understand the development of protrusion mechanics we performed kinematic and morphological studies of the orange clownfish (Pomacentridae; Acanthomorpha) and the zebrafish (Cyprinidae; Cypriniformes) using extensive developmental series of each. Our results show that protrusion ability manifests late in development and is strongly associated with metamorphosis and remodeling of the skull during the larval to juvenile transition. This work indicates that studies of skull metamorphosis have the potential to illuminate the developmental underpinnings of evolutionary success in an extensive portion of the vertebrata.
