As vertebrates moved into new ecological spaces the skull diversified in size, shape, and became adorned with ornaments and weapons. It is no surprise, therefore, that the skull has fascinated researchers across the entirety of Biology over the past century. In more recent decades, understanding the developmental bases of craniofacial diversity has been a major goal of Evolutionary-developmental biology. However, a paucity of experimental systems among amniotes ? reptiles, birds, and mammals ? has made it difficult to create a synthetic understanding of how developmental patterning has changed during the remarkable diversification in skull form. In this research Dr. Sanger will dissect skull development in an emerging model lizard, Anolis sagrei. Sanger and his team will investigate the expression and function of three core signaling pathways known to be involved in skull development in other amniote species. Through this research they will discover whether the diversity in skull form is due to minor or major changes in craniofacial patterning. Capitalizing on the inherent interest in the vertebrate skull, Sanger will also team with a group of professional educators to develop "Getting Ahead in Life: Investigations into the Vertebrate Skull", cutting-edge, transdisciplinary learning modules targeted to upper level high school and undergraduate biology. Embedded within these modules will be interviews and real-world data from leaders in the field of craniofacial biology, especially people from groups underrepresented in STEM. Together, Sanger?s efforts will significantly advance the field of craniofacial development and help motivate the next generation of students to pursue education in STEM fields.
One of the most morphologically and developmentally complex anatomical systems is the vertebrate skull. Although there is coarse similarity in cranial embryology among these groups, there is growing, yet disparate, evidence to suggest that cranial patterning has evolved over both small and large evolutionary scales. To date, however, our understanding of facial development has primarily arisen from only a few experimentally accessible avian and mammalian species, making it difficult to make broad generalizations about the evolution of cranial development. Uncovering the function of key patterning genes in previously undescribed clades is a critical step towards polarizing the evolution of cranial patterning mechanisms and to help elucidate the ancestral character state of amniotes. In this research Sanger and his team will investigate the expression and function of three core signalizing pathways involved in craniofacial development: Hedgehog, Fibroblast growth Factor, and Bone morphogenetic protein. This team will use new tools to manipulate the expression of these pathways in embryos of Anolis sagrei, an emerging model system in Developmental Biology, but a historically important species in Ecology and Evolutionary Biology. With this baseline information in hand, Sanger will turn towards evolutionary patterns of skull diversity on a smaller scale, among Anolis lizards. Anolis lizards vary extensively in their facial length. Multiple lineages have independently converged on short-faced and long-faced morphologies. Sanger and his team will also determine the developmental bases of these convergent phenotypes. Combined, this research will determine how the processes regulating craniofacial development evolve over different evolutionary time scales.
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.
