Rock-Ground Patchiness in a Simple Liolaemus Lizard Community (Reptilia, Lacertilia, Iguanidae)

Lizard communities in Chile and California have been shown (Fuentes, 1976) to exhibit rock versus ground microhabitat partitioning. In this paper we investigate two hypotheses explaining this phenomenon (1) zonation due to differences in food requirements by the species and (2) zonation due to different needs for hiding places from predators. Observations and collections of two species of Liolaemus (Iguanidae) lizards in a simple habitat suggests: (1) the two lizard species do not differ significantly in their food preferences and (2) morphological and behavioral differences between species can be related to different predation risks. In addition to reporting on lizard predators this paper shows that the species using rocks, presumably the more protected area, tends to be larger, more color and size dimorphic than the species foraging preferentially on the open ground. A natural experiment of decreased effective bird predation risk, further suggests predation is a likely factor in the explanation of rock-ground zonation in these lizards. The roles of interspecific competition and lizard predation are discussed in relation with the Liolaemus community we investigated.