A single residue confers selective loss of sugar sensing in wrynecks

Sensory receptors evolve, and changes to their response profiles can directly impact sensory perception and affect diverse behaviors, from mate choice to foraging decisions. Although receptor sensitivities can be highly contingent on changes occurring early in a lineage’s evolutionary history, subsequent shifts in a species’ behavior and ecology may exert selective pressure to modify and even reverse sensory receptor capabilities. Neither the extent to which sensory reversion occurs, nor the mechanisms underlying such shifts is well understood. Using receptor profiling and behavioral tests, we uncover both an early gain and an unexpected subsequent loss of sugar sensing in woodpeckers and wrynecks, members of the primarily insectivorous Picidae family of landbirds. Our analyses show that, similar to hummingbirds and songbirds, the ancestors of woodpeckers repurposed their T1R1-T1R3 savory receptor to detect sugars.  Importantly, whereas woodpeckers seem to have broadly retained this abi...