Multiple amino acid changes are responsible for the shift of tuning breadth along the evolutionary trajectory of a moth pheromone receptor.

Sex pheromone recognition is essential for mating in many insects and plays a major role in maintaining reproductive barriers. A previous study from our lab reported the evolutionary history of the pheromone receptor OR5 in Spodoptera moths. Using heterologous expression in Xenopus oocytes and site-directed mutagenesis, we found that eight amino acid substitutions were sufficient to recapitulate the evolution from an ancestral broadly-tuned to a highly specific receptor. Here, we confirmed this result using expression in Drosophila olfactory neurons. This further confirmed that multiple amino acid changes explain the shift in tuning breadth of Spodoptera OR5 during evolution.