Meeting Abstract
Filling evo-devo’s developmental gap: metamorphosis, integration and functional evolution Animal Evo-Devo has focused almost exclusively on embryonic stages, but most evolutionary morphological studies examine adult characters. Adults and embryos are very different. Adult morphology is the product of extensive developmental remodeling of embryonic structures. We lack an understanding of how changes in remodeling mechanisms have facilitated the evolutionary diversification of adult form. Most animals undergo a physical metamorphosis (extensive anatomical remodeling) that coincides with a shift in habitat. Furthermore, many species possess complex biomechanical abilities that arise during metamorphosis. The functional integration of complex structures requires the morphological integration of their sub-components. Metamorphosis may therefore: 1) play a significantly larger role in determining adult form and ecology than embryogenesis, and 2) represent an important developmental mechanism for establishing integration. Since integration is a critical feature in shaping diversification, metamorphosis may be of strong importance to determining evolutionary potential. The developmental mechanisms that direct integration are only poorly known. Thyroid hormone (TH) signaling is the predominant determinant of animal metamorphosis and represents an important target for Evo-Devo research. Here we present data which indicate that TH signaling is important for establishing the morphological and functional integration of zebrafish jaws. Comparative analyses of the functional morphology of feeding in closely related species suggest that modulation of TH signaling may have played an important role in the diversification of fish feeding mechanisms.
