The structure of the limb is fundamental to a mammal's feeding, movement, and behavioral adaptations. For example, the wings of bats enable powered flight, the flippers of whales an aquatic lifestyle, and the one-toed hooves of horses rapid movement on land. Species differences in mammalian limb structure have arisen primarily through evolutionary fine-tuning of the limb's basic structures (upper arm/leg, lower arm/leg, hand/foot) that form during late gestation. However, it is possible that this diversity initiates much earlier during embryonic development. This study focuses on defining the morphological and molecular differences of the embryonic limbs between diverse mammalian species, including bat, opossum, and mouse. Modern molecular biology and computational methods will be used in these studies. This project represents the first comprehensive, multi-species comparison of mammalian limb development, and therefore has the potential to yield transformative insights into the fundamental mechanisms controlling limb development and how they have impacted mammalian limb evolution. Furthermore, since humans are mammals, these studies will directly advance an understanding of the mechanisms that have shaped human evolutionary history. This collaborative project with Dr. Karen Sears (University of Illinois) and Dr. Chris Cretekos (Idaho State University) exploits the collective expertise of this group in mammalian embryology, molecular biology, paleontology, evolutionary biology, and laboratory and field biology to synergistically approach this biological topic in an innovative manner. This evolutionary developmental biology study emphasizes research using mammalian models that are understudied, i.e. the bat and the marsupial opossum. The broader impact of these studies on biological research will be to expand knowledge and training beyond the more typically studied rodents like the mouse for a holistic understanding of limb diversity and evolution.
