We use an integrative approach leveraging the deer mouse (Peromyscus maniculatus) system to uncover the neural basis of ecologically relevant motor behavior and to understand how nervous systems evolve to support behavioral adaptation. When glaciers receded from North America ten thousand years ago, some deer mice moved into newly available forests, whereas others continued to live in prairie habitats. Over time, these populations diverged, giving rise to forest-adapted deer mouse subspecies that exhibit dexterous motor abilities, including climbing, and prairie-adapted subspecies that do not. This adaptation to forest habitats occurred repeatedly in multiple forests across the continent, resulting in independent "evolutionary replicates”, i.e., multiple forest-adapted deer mouse subspecies with similar dexterous behaviors. 

We capitalize on the natural variation in behavior, neural circuitry, and genetics resulting from this evolutionary history to uncover the mechanistic bases of ecologically relevant dexterity. We have identified several neural populations that have increased in number in forest compared to prairie deer mice, including corticospinal neurons, which reside in cortex and send axons to the spinal cord. Questions we’re excited to address include: (1) What are the developmental and genetic bases of the neural and behavioral differences between forest and prairie mice? (2) How do differences in neuron number impact circuit function and behavior? (3) Did dexterity evolve via different behavioral, neural, or genetic mechanisms in different evolutionary replicates?