The purpose of our project is to understand the evolution of the hypothalamus across major vertebrate classes. The hypothalamus has been well conserved across evolution and regulates many physiological functions necessary for life across all vertebrates. However, different vertebrate classes evolved unique abilities to survive on Earth, eg. living underwater, endothermy, and shelled amnia, likely selecting for different cell types in the hypothalamus. In this project, we are establishing single-nucleus RNA sequencing landscapes of the hypothalamus of major vertebrate classes in response to unique environmental pressures.