Body Size and Habitat Utilization in Whiptail Lizards (Cnemidophorus)

In certain groups of the teiid lizard genus Cnemidophorus, the larger species tend to be restricted to habitats that are shaded, relative to the open habitats of smaller species. Body size affects the rate of heat exchange with the environment, and plays a relatively direct role in determining the thermospatial niche of these lizards. Field and laboratory studies show that larger lizards bask less and spend more of their activity period in the shade than do smaller lizards with the same thermal preferenda and tolerance limits. Variation of body size in Cnemidophorus may reflect adaptation to differences in the structure of vegetation, relatively larger lizards being more successful in relatively shaded habitats.