Evolution of Brain Development in Birds

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The principal aim of the proposed research is to determine what evolutionary changes in developmental mechanisms have caused parrots and songbirds to evolve disproportionately large forebrains. This work is important because disproportionately large forebrains evolved several times independently (e.g., parrots, songbirds, primates, dolphins and whales) and seem to make their bearer's "smart" in a variety of ways. Yet almost nothing is known about how evolution creates enlarged forebrains. Developmental biologists can make genetically modified animals that have unusually large brains because they vary in some aspect of brain development, such as having reduced levels of neuronal cell death. However, these mutant animals tend to die as embryos and never become "smarter". The approach in the proposed work is to inquire of Nature how it manipulated brain development to create "smarter" animals with enlarged forebrains. Specifically, brain development will be compared in a parakeet, a zebra finch and a quail, asking which cellular or molecular mechanisms differ between these species. If Nature used the same mechanism to produce enlarged forebrains in parrots and songbirds, then this suggests the existence of a constraint that must be satisfied in order to obtain well-functioning enlarged forebrains. Knowledge of this constraint would, in turn, inform future attempts to mimic some aspects of brain evolution in laboratory experiments. It would also improve understanding of the mechanisms that underlie the evolution of increased forebrain size and increased intelligence within the human lineage. The proposed work will support the training of two PhD students and at least four undergraduate students who do independent research. The PI is committed to broadening participation of students at all levels and is involved in community outreach programs and monthly series for K-12 students.