Morphological variation and diet in two Liolaemus elongatus Koslowsky, 1896 (Iguania : Tropiduridae) populations from northwestern Patagonia

Morphology and diet of two Liolaemus elongatus populations from northwester n Patagonia, consisting of a steppe and a forested patch, and 30 km apart f rom each other, were studied. The variation between populations and sexes o f the coloration and design pattern, the most relevant metrical parameters, and that of composition and diversity of the digestive contents was examin ed in 22 steppe and 25 forest adult specimens. Populations differed in colo ration, design pattern and average body size, with individuals from steppe being larger. Variation in color could be related to either genetic or sele ctive factors. The lower altitude of the steppe zone might account for the bigger size of individuals therein. No sexual dimorphism was detected eithe r in coloration or body size in individuals of both populations. Regarding diet, individuals from both populations appeared to feed mainly on ants (Fo rmicidae). Nonetheless, plant material was frequent, which contradicts prev ious opinions that considered the species as being exclusively insectivorou s. Availability of plants could therefore be a major influence on the tende ncy of this species towards omnivory. Differences in diet between the two p opulations could be related to different ecological parameters and/or to in trinsic characteristics of the populations.