Bitter Taste Receptor Evolution in Primates

Bitter taste receptors are important for detecting toxins in the environment, particularly in the leaves of plants. To explore the selection pressures on bitter taste receptor genes, Wooding sequences the TASR38 gene from 40 phylogenetically disparate primate taxa. He found considerable variation (more than expected), but still an overall theme of purifying selection. Notably, signatures of selection were variable based on domain; for instance, the second external loop of the receptor (extracellular region) underwent strong positive selection indicating changes in ligand targeting. Cool stuff!