Discipline: Ecology Environmental and Earth Sciences
Subcategory: Ecology
Bryan Juarez - Iowa State University
Co-Author(s): Lauren C. Sallan, University of Pennsylvania, Philadelphia, PA
Patterns of vertebrate cranial/post-cranial trait diversification are not well-understood. These patterns of trait diversification between species are important in understanding how ecology results in the morphological and functional diversity of organisms. Two ecological hypotheses, the ‘head-first’ model and the ‘stages’ model, predict the ordered decoupling of cranial/post-cranial ecomorphological diversification. Rate (tempo) analyses and macroevolutionary model-fitting (mode) analyses are often used to test whether cranial traits or post-cranial traits diversify earlier in vertebrates. Here we reconstructed the tempo of cranial/post-cranial trait evolution in lobe-finned fishes (Sarcopterygii), a group containing coelacanths, lungfishes, and tetrapodomorph fishes, to test for differences in the timing of vertebrate cranial/post-cranial trait diversification. We hypothesize, primarily based on previous research of aquatic vertebrates, that we will observe a ‘head-first’ cranial pattern of skeletal diversification. We collected full-skeletal geometric morphometric coordinate and PC-reduced data for ~100 species of aquatic and semi-aquatic lobe-fins since the Paleozoic and performed rate and raw disparity through time analyses using both coordinate data and principal component-reduced data. We conclude that cranial ‘head-first’ ecomorphological diversification drove the early Paleozoic radiation of aquatic and semi-aquatic lobe-fins, but more research may be needed to understand conflicting patterns in the Mesozoic when taxonomic diversity was substantially lower among “living fossils”.
Not SubmittedFunder Acknowledgement(s): NSF, Frontiers Master's Program at University of Michigan, University of Michigan EEB Program, University of Michigan Museum of Zoology, Rackham Graduate School
Faculty Advisor: Lauren C. Sallan, laurensallan@gmail.com