Dissertation Research: Evolution, development and functional morphology of damselfish oral jaws.
Mark W. Westneat and W. James Cooper The Field Museum of Natural History and The University of Chicago
The evolution of new anatomical arrangements and novel functional abilities involves alterations in how physical structures form during development. Understanding the evolution of vertebrate feeding therefore requires examination of the developmental changes that have produced skulls with different biomechanical abilities. For marine fishes such as damselfishes (Pomacentridae: Labroidei), evolutionary changes in skull development have functional consequences for feeding larvae and juveniles. This research will employ a combination of shape analyses, gene expression studies and biomechanical modeling to describe developmental changes in the shape and function of the skulls of damselfishes, a numerically dominant component of coral reef fish faunas. A detailed examination of adult skulls from all damselfish genera will provide the initial framework for determining how developmental changes have contributed to damselfish morphological and functional evolution. By combining the results of shape analyses with computer models capable of predicting the biomechanical abilities of fish jaws (e.g. bite force, biting speed, degree of jaw protrusion) we will be able to describe the connection between skull shape diversity and oral jaw functional diversity within this fish family. Several damselfish species will then be bred in captivity so that their embryos may be collected for developmental study. Examination of embryonic gene expression patterns will permit testing of the hypothesis that differences in the location and timing of expression of selected regulatory genes are correlated with differences in adult damselfish jaw morphology and functional abilities. Embryos of the false clown anemonefish (Amphiprion ocellaris), the spine-cheek anemonefish (Premnas biaculeatus) and the Garibaldi (Hypsypops rubicunda) have already been collected for this purpose. Hatched larvae of these species (and potentially other species as well) will also be reared through successive larval and juvenile stages in order to track changes in skull shape and biomechanical ability throughout development. Aspects of the proposed research have been, and will continue to be, incorporated into public school courses through collaboration with a local teacher.
