BRC-BIO: How the evolution of duck foot shape relates to swimming ability - from morphology to robophysical models

Webbed feet have evolved multiple times in swimming animals, including the well-known webbed "triangles” of duck feet. However, from pond dabblers to deep-sea divers, duck swimming ability varies considerably among species, and how foot anatomy contributes to this variation has yet to be investigated. This project will quantify duck foot shape by looking at both the skeleton and foot webbing. Then physical models of duck feet will be robotically actuated to directly measure how aspects of foot shape and paddling behavior influence swimming force production. The findings of this study will apply to numerous fields by inspiring designs of industrial, commercial, and robotic paddles (e.g., hydroelectric turbines, boat sails, scuba flippers). Further, by helping explain ecological and evolutionary patterns in birds, our results have the potential to inform conservation initiatives and paleontology research. In addition to the direct impact of these findings, a major goal of this project is to promote diverse future STEM researchers by supporting undergraduate biology students through their first research experience. Funding from this project will establish a professional development program (PDP) for 10 undergraduates per year. Each annual PDP will meet weekly over the summer of the first research experience and during the subsequent fall semester to build a supportive community for students while providing workshops that develop advantageous skills for future graduate studies or science careers.More specifically, the first half of this project aims to identify evolutionary patterns in duck foot shape by measuring bone dimensions and toe splay broadly across duck species. Undergraduate students will analyze foot bones using CT-scans of duck specimens, including a visit to the Natural History Museums of LA County to choose specimens and learn about museum collections. Foot bone data will be coupled with shape analysis of webbed feet through photography and 3D scanning of collected specimens. Together, these morphological data will provide the basis for phylogenetic analyses to identify evolutionary patterns among species. The second half of this project aims to directly relate anatomical variation in foot shape to swimming performance. Informed from the measurements in the first section, students will construct 2D and 3D physical models of duck feet that vary in shape. These models will be robotically-actuated in a water flume while directly measuring hydrodynamic forces using force sensors and visualizing flow patterns using Particle Image Velocimetry. The project will initiate a productive collaboration capable of extending investigation into webbing material properties, complex paddling kinematics, and webbed foot diversity among non-bird paddling animals (e.g., frogs, aquatic mammals). The results will reveal a critical component of avian evolutionary history and provide a crucial framework for analyzing fossils of extinct dinosaur and bird species.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.