Molecular evidence for the loss of three basic tastes in penguins.

Sensing its biotic and abiotic environmental cues is critical to the survival and reproduction of any organism. Of the five traditionally recognized senses of vertebrates, taste is dedicated to the differentiation between nutritious and harmful foods, triggering either appetitive or rejective behaviors. Vertebrates typically can detect five basic taste qualities: sweet, umami, bitter, sour and salty. Remarkable progress in understanding the molecular basis of taste has opened the door to inferring taste abilities from genetic data. Based on genome and relevant gene sequences, we infer that the sweet, umami, and bitter tastes have been lost in all penguins, an order of aquatic flightless birds originating and still occupying the coldest ecological niche on Earth, the Antarctic.