Meeting Abstract
A major aim in evolutionary biology is to explain the origin of morphological diversity. Many studies attribute morphological diversity to adaptations for particular ecological niches, with divergent selection enhancing adaptive differences. While natural selection may occur throughout the life history of an organism or at specific stages, few studies focus on ontogeny of morphological diversity and its role in adaptive divergence. In this study I investigated the ontogeny of wrasse functional morphology within a group that demonstrates diverse and novel adult feeding: the Thalassoma and Gomphosus clade within the Labridae. We utilized museum collections to compile morphometric data on an ontogenetic series of nine wrasse species. Dissections were performed on the right side of the head to expose the adductor mandibulae complex and record 20 functionally relevant, homologous landmarks. Geometric morphometric analyses and a phylomorphospace approach reveal patterns of divergence and convergence in skull shape across the phylogeny of Thalassoma, and show that the novel biomechanics of Gomphosus correlate with occupation of novel morphospace. Biomechanical modeling using the apps MandibLever 3.2 and JawsModel 4.0 was used to investigate differences in feeding kinetics throughout ontogeny and phylogeny, revealing that novel mechanics in Gomphosus are associated with changes in jaw levers while leaving the anterior jaws four-bar linkage static. High-speed video of feeding reveals an unusual two-stage biting strategy in these fishes that is also highly divergent in Gomphosus, reflecting these morphometric changes. These results shed light on rapid evolution of jaw mechanics at the interspecific level as well as important stages of selective pressure that may occur throughout the complex life cycle of wrasses, and its role in adaptive divergence of this diverse group. Supported by NSF DEB-1112763 and IOS-1425049.
