Background Color-Matching In The Texas Horned Lizard (Phrynosoma Cornutum)

Abstract

Most of the literature on the basic ecology of Texas horned lizards cites "cryptic color pattern" as the first line of defense against predation in this taxon, and yet the degree to which horned lizards color-match their backgrounds has never been quantified. Several zoos and state wildlife agencies are releasing captive-bred and translocated lizards to parts of their former range; however, the new populations are not self-sustaining, with most releases lost to predation. Background color-matching may be important to consider when moving lizards into a new habitat where predation may be higher if they are not closely color-matched to the local soils. I quantify background color-matching in this taxon across its known range in the United States and in Mexico from in situ photos taken, as found, in the wild. I also present background color-matching variation and trends both within and between phenotypically and genetically diverse populations and ask whether lizards more closely match their local soil colors and sun-bleached plant stems than soils and stems from other areas. Finally, I suggest a method for zoos and wildlife agencies to score coloration in their captive populations of lizards, thus possibly enabling these institutions to objectively consider color-matching a priori as an applied conservation strategy to potentially increase the survival of reintroduced Texas horned lizards.