A major goal of biology is to identify the processes that shape the evolution of form and structure. To pursue this important goal, this project will take an innovative, comparative approach to investigate how evolutionary changes during limb development (the process by which the limb forms) contribute to the generation of the divergent limbs of three mammals: bats, opossums, and mice. The mammal limb is an ideal system with which to pursue this goal because the way that a mammal feeds, moves and behaves is dependent upon the form of its limbs. As such, from the wings of bats to the flippers of whales to the hooves of horses, the diversification of the mammal limb has been crucial to the ecological and evolutionary success of the group. Through use of traditional and next generation genetic analyses, this project will identify the specific changes in gene expression (e.g., when genes are turned on and off, and at what levels) that initiate and drive the divergence of limb form among mammalian species. This knowledge will vertically advance our understanding of how the process of development constrains and facilitates the evolution of certain limb forms, and thereby impacts mammalian evolution. Furthermore, as humans are mammals, this project will directly advance our understanding of the processes that have shaped our own evolutionary history.
