Bat species are numerous and diverse, and are found in nearly every corner of the globe. Therefore, they serve as a valuable system to study the evolution of mammalian traits. Dr. Alexa Sadier collected field and museum samples from over 50 species of bats to ask how color vision evolved in this unique group of mammals. By looking at gene expression at multiple levels - DNA, RNA, and protein - Sadier determined that different bat species have color vision capabilities adapted to their diets, and UV vision has been lost independently in multiple species through regulation of all levels of gene expression. By “catching” evolution in action, Sadier’s research has revealed important insights into the mechanisms of evolution through trait loss.