Evolution's Rainbow. Joan Roughgarden

the phrase “male mimicry” is not introduced. Females are not seen as deceiving males. If this was a case of male mimicry, the males who do try to mate with green females would have to be mistaking the females as males and soliciting a same-sex courtship, something not (yet?) described in this species.

      A comparable lizard species in western Ecuador, Microlophus occipitalis, also has females that display a special color when unreceptive to courtship.⁸ Hatchlings of both sexes have red throats and chins for about a month. Then males lose the red pigment, while females retain some of the red in skin folds on the side of the neck. The males develop black markings on their back and grow larger than the females.

      During the reproductive season, some females develop bright red pigmentation covering the throat and chin similar to that of juveniles. Imagine painting Texas-red on your chin and neck, all the way down to your breastbone: you’ll get noticed. Females wear red on their chin and neck when carrying undeveloped eggs in their oviducts or after laying eggs. Males were found to make more courtship approaches to nonred females and pursue the courtship with them more ardently. Conversely, red females rejected courtship advances more than nonred females did. Out of thirty-eight matings observed during three years of study, thirty-three involved either unpigmented females or ones with but a small trace of red, whereas only five involved fully red-throated females.

      Thus females in both Spanish and Ecuadorian lizards signal when they are not receptive. In the Spanish species, the signal (green on the back) is a color that males coincidentally also have on their backs, whereas in the Ecuadorian species the signal (red on the chin and neck) is distinctive from the color that males have on their chins and necks. Bright colors have been described in the females of more than thirty species of lizards so far, and in eighteen of these, the bright colors are expressed when the females are carrying oviductal eggs.⁹ Thus females using color to signal to males to back off is apparently quite general in lizards.