Choosing between a rock and a hard place： Camouflage in the round-tailed horned lizard Phrynosoma modestum  

作　　者：William E. COOPER, Jr. Wade C. SHERBROOKE 

机构地区：[1]Department of Biology, Indiana University Purdue University Fort Wayne, Fort Wayne, IN 46805, USA [2]Southwestern Research Station, American Museum of Natural History, PO Box 16553, Portal, AZ 85632, USA

出　　处：《Current Zoology》2012年第4期541-548,共8页动物学报（英文版）

摘　　要：The round-tailed homed lizard Phrynosoma modestum is cryptically colored and resembles a small stone when it draws legs close to its body and elevates its back. We investigated effectiveness of camouflage in P. modestum and its dependence on stones by placing a lizard in one of two microhabitats （uniform sand or sand with surface rocks approximately the same size as lizards）. An observer who knew which microhabitat contained the lizard was asked to locate the lizard visually. Latency to detec- tion was longer and probability of no detection within 60 s was higher for lizards on rock background than on bare sand. In arenas where lizards could choose to occupy rock or bare sand, much higher proportions selected rocky backgrounds throughout the day; at night all lizards slept among stones. A unique posture gives P modestum a rounded appearance similar to many natural stones. Lizards occasionally adopted the posture, but none did so in response to a nearby experimenter. Stimuli that elicit the posture are unknown. That P. modestum is better camouflaged among rocks than on bare sand and prefers to occupy rocky areas suggests that special resemblance to rocks （masquerade） enhances camouflage attributable to coloration and immobility.

关 键 词：Animal defense Background matching CAMOUFLAGE CRYPSIS MASQUERADE SQUAMATA 

分 类 号：Q959.62[生物学—动物学] V261.933[航空宇航科学与技术—航空宇航制造工程]