Sensing in Nature

Emily R. Liman

Sensory organs provide key, and in many cases species-specific, information that allows animals to effectively forage, find mates and avoid hazards. The primary sensors for the vertebrate senses of vision, taste and smell are G-protein-coupled receptors (GPCRs) expressed by sensory receptor cells that initiate intracellular signal transduction cascades in response to activation by appropriate stimuli. The identification of sensory GPCRs and their related downstream transduction components from a variety of species has provided an essential tool for understanding the molecular evolution of sensory systems. Expansion of the number of genes encoding sensory GPCRs has, in some cases, expanded the repertoire of signals that animals detect, allowing them to occupy new niches, while in other cases evolution has favored a reduction in the repertoire of receptors and their cognate signal transduction components when these signals no longer provide a selective advantage. This review will focus on recent studies that have identified molecular changes in smell, taste and pheromone detection during primate evolution.