OEB Seminar Series

Hopi Hoekstra
Harvard University, Department of Organismic and Evolutionary Biology
"How the mouse got its stripes"

Abstract:  Color patterns are among the most conspicuous traits found in nature and can have a profound impact on fitness. However, little is known about the mechanisms underlying their formation and subsequent evolution, especially in mammals. In this talk, I will show that, in the African striped mouse (Rhabdomys pumilio), their dorsal stripes result from underlying differences in pigment cell maturation, which gives rise to spatial variation in hair color. Next, we identify a transcription factor (TF) that regulates this process. In the dorsal skin of embryos, patterned expression of this TF foreshadows pigment stripes, and acts to directly repress the master regulator of melanocyte differentiation, giving rise to light-colored hair. Moreover, this same TF is also upregulated in the light stripes of chipmunks, which have independently evolved a similar pattern of dorsal striping. Our results reveal a previously unappreciated mechanism for modulating spatial variation in pigmentation, and provide new insight into the ways in which phenotypic novelty evolves.