9407367 Gatesy Species of animals can differ in the number, arrangement and function of their muscles. This research seeks to understand the relationship between muscle form and function and how this can change with time. The PI will study a group of muscles in the thigh of birds called the deep dorsal thigh muscles. During embryonic development, a mass of cells breaks up, or cleaves, to form the individual muscles present in adults. Some birds, such as the chicken or guineafowl, have four separate deep dorsal thigh muscles. However, in other birds, the deep dorsal muscle mass may not cleave completely, yielding less than four adult muscles. For example, the pigeon and the duck only have three deep dorsals, while a roadrunner has only two. The PI is interested in knowing what effect this variation in number and position has on the function of these muscles. Using fine wires as electrodes, the PI will record electrical changes that reveal when a muscle is contracting. Previous studies have shown that as a guineafowl walks or runs, deep dorsal thigh muscles are active at different times in the stride. When will the deep dorsals be active in birds with fewer than four muscles? Do new muscles evolve to perform new functions or movements? How does the nervous system change when muscle anatomy changes? Through questions such as these, the PI hopes to gain a better understanding of animal design and the evolution of vertebrate diversity. ***
