Luminosity of C. columbae after four years of experimental evolution on rock pigeons, compared to (A) C. masoni from a dark‐colored host species, the Australian chestnut‐quilled pigeon (Petrophassa rufipennis), and (G) C. wolffhuegeli from a light colored host species, the Australian pied imperial pigeon (also shown in Fig. 1A). Images of experimentally evolved lice in B–F are: (B) one of the darkest C. columbae from a black rock pigeon, (C) average C. columbae from a black rock pigeon, (D) average C. columbae from a gray rock pigeon, (E) average C. columbae from a white rock pigeon, and (F) one of the lightest C. columbae from a white rock pigeon. Whisker plots show means (diamonds), medians (vertical lines), 1st and 3rd quartiles (boxes), and 1.5 interquartile ranges (whiskers). Letters above whisker plots indicate the luminosity of corresponding photographs. Sample sizes: 7 C. masoni, 18 C. wolffhuegeli, and 74, 36, and 50 C. columbae from black, gray, and white rock pigeons, respectively. Photos of lice by JCA and SMV.