CAREER: Macroevolutionary Biomechanics: Integrating Morphology, Mechanical Models, and Phylogenetic Comparative Methods to Understand the Evolution of Swimming Performance in Frogs

Biomechanics has contributed a rich understanding of the physical principles that dictate organismal form and function, but the field has been slow to incorporate study of the evolution of mechanical diversity. In this CAREER project, the principal investigator (PI) will combine experiments on live organisms, computer modeling, and statistical analyses of the evolution of species differences to understand the evolution of diversity of body form and movement. The project will focus on (1) how different body structures scale with body size; (2) how the size of these structures and different behavioral strategies affect aquatic locomotion (i.e. swimming); (3) how sensitive swimming performance is to variation in such variables; and (4) how these relationships between form and function have affected long-term evolutionary change in swimming performance across >140 species of frogs and toads around the world. The key intellectual contribution of the project will be to develop an evolutionarily explicit approach to studies of form, function, and their diversity across species. The project will also more broadly support scientific capacity in the USA by (1) training secondary science teachers in research methods, evolutionary concepts, and integration of research into their classrooms; (2) training undergraduate students in the study of animal movement and research methods through in-class research projects; and (3) training young researchers in biomechanics to more directly incorporate evolutionary analysis methods into their projects. This project integrates biomechanical modeling, kinematics from high-speed videos, and phylogenetic comparative methods to understand the evolution of form-function relationships and their impact on macroevolution of morphology and swimming performance in anurans. The project has three key aims. In Aim 1 the PI will examine the evolution of allometry in locomotor morphology, highlighting how to leverage phylogenetic comparative methods to best estimate interspecific allometric scaling exponents. In Aim 2, he will address the mechanics and scaling of swimming in anurans. He will develop and empirically test a mathematical model of the complete swimming stroke in frogs, then use the model and phylogenetic comparative methods to explain the scaling between peak swimming velocity and body mass. In Aim 3, the PI will examine the sensitivity of swimming performance to different morphological variables through both mathematical and statistical modeling, and he will test the tempo and mode of morphological and swimming performance evolution as a function of mechanical sensitivity. The intellectual merit of the project primarily stems from integrating disparate methods (experiments, mathematical modeling, phylogenetic analyses) and providing an evolutionary comparative framework for testing general physical principles and their influence on the macroevolution of form and function. The broader impacts of the project will result from developing secondary education in scientific research and evolutionary concepts in the PI's state, integrating research training into undergraduate laboratories, and training young researchers in biomechanics in phylogenetic comparative methods workshops. This project is jointly funded by the Physiological Mechanisms and Biomechanics Program of BIO-Integrative Organismal Systems and the Established Program to Support Competitive Research (EPSCoR). This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.