African striped mouseJ.F. BROEKHUIS Laboratory mice come in a variety of colors, thanks to selective breeding, but in the wild, most mice are brown, according to biologist Ricardo Mallarino. The wild African striped mouse is a drab color too, but its coat also has a distinctive feature: alternating dark and light stripes down the middle of its back. Mallarino, a postdoc in the Harvard University lab of Hopi Hoekstra, and colleagues have now found that these stripes develop through a newly identified mechanism of varying pigmentation. Further, the African striped mouse (Rhabdomys pumilio) shares both the stripes and the mechanism with the Eastern chipmunk (Tamias striatus), the researchers report today (November 2) in Nature.
Hoekstra is interested in how pigment patterns—like stripes—confer fitness advantages for mammals, as well as how these patterns evolved. Unlike lab mice, both African mice and chipmunks are active during the day. For that reason, “they’re really subject to predators that hunt visually as opposed to things that, you know, scurry around at night,” Hoekstra told The Scientist. Some scientists have suggested that stripes may help animals escape these keen-eyed predators, perhaps by making it more difficult for them to see where the animals begin and end, Hoekstra noted.
In an attempt to understand not only why, but how striped rodents acquire these auspicious patterns, Hoekstra and colleagues compared the pigments and cell types present, as well as gene expression, within the tissues that make ...
