Meeting Abstract

12.5  Jan. 4  Between the Devil and the Deep Blue Sea: Conspicuousness of Dickerson�s Collared Lizard (Crotaphytus dickersonae) Through the Eyes of Conspecifics and Predators MACEDONIA, J.M.*; LAPPIN, A.K.; LOEW, E.R.; MCGUIRE, J.A.; HAMILTON, P.S.; PLASMAN, M.; BRANDT, Y.; LEMOS-ESPINAL, J.A.; Arizona State University, Tempe; Northern Arizona University, Flagstaff; Cornell University, Ithaca, NY; University of California, Berkeley; Arizona State University, Tempe; Utrecht University, The Netherlands; University of Toronto, Ontario, Canada; University Nacional Autonoma de Mexico, Tlalnepantla Joseph.Macedonia@asu.edu

Collared lizards (Crotaphytus) are rock-dwelling reptiles endemic to the western USA and Mexico. Most Crotaphytus species exhibit dull coloration to avoid detection by predators and by potential lizard prey, but adult male Dickerson�s collared lizards (Crotaphytus dickersonae) � a species restricted to Isla Tiburon in the Sea of Cortez and adjacent coastal mountains in Sonora, Mexico � are bright blue (females are largely brown). We used visual modeling to investigate the differential conspicuousness of C. dickersonae to conspecifics and to snake and bird predators. Predation pressure and saurophagy (lizard eating) also were assessed. Disparity analysis of contrast between lizard color patterns and their visual backgrounds revealed that C. dickersonae males were more conspicuous in coloration than females in all visual models, and with one exception both sexes were more conspicuous to their own visual system than to snake or avian visual systems. Although males were highly conspicuous against rocks, they were relatively inconspicuous against the background of the sea, especially to avian predators. Comparisons with males from two �blue� Crotaphytus collaris populations suggested that natural selection may have fine-tuned blue body coloration in C. dickersonae males to reduce detection by predators (the �devil�) when viewed against the prominent visual background of the sea.