Tree shrews violate mammal rules!

Tree shrews, a species closely related to primates, seems to violate the mammal rules as they tolerate spices unlike other members of their species.

Spicy foods elicit a pungent or hot and painful sensation that repels most mammals.

The researchers at Chinese Academy of Science observed tree shrews directly and their activeness while consuming chili peppers, despite the deep geographic isolation between the animal and the food.

They performed genomic and functional analyses on the tree shrew and its TRPV1.

The research revealed that a single point mutation in the tree shrew's transient receptor potential vanilloid type-1 (TRPV1, a polymodal nociceptor) ion channel (tsV1) lowers its sensitivity to capsaicinoids, thus enabling tree shrews' unique feeding behavior regarding pungent plants.

The experimental evidence suggests that strong selection for this residue in tsV1 might be driven by Piper Boehmeria folium. It is a spicy plant that geographically overlaps with the tree shrew and produces Cap2, a capsaicin analog, in abundance.

Therefore, researchers concluded that feeding adaptation to Piper Boehmeria folium is the most likely explanation for the fixation of this mutation by positive selection, thus allowing the tree shrew's diet to expand.

The findings appeared in the Journal of PLOS Biology.