Female Color Change in the Keeled Earless Lizard, Holbrookia propinqua: Relationship to the Reproductive Cycle

The orange and yellow coloration of female Holbrookia propinqua appears to be closely associated with ovarian events, intensifying rapidly during the final stages of vitellogenesis and reaching maximum brightness prior to ovulation. All females having recent corpora lutea or bearing oviducal eggs retained bright colors. Females with the dullest colors lacked orange and yellow pigmentation, had relatively small follicles, and were at early stages of the reproductive cycle. Further studies are needed to determine the course of chromatic variation between successive reproductive cycles and to evaluate the turn-on and turn-off hypotheses of the adaptive value of the female reproductive coloration.