Climate, Competition, and the Structure of Temperate Zone Lizard Communities

The roles of climate and competition in relation to the structure of temperate zone lizard communities were investigated. Lizard species richness was positively related to mean January temperature, but negatively related to warm—season precipitation and mean July temperature. Generic groups showed little overlap in morphological factor space but considerable overlap in habitat use. Species that were similar in either morphology or habitat use were dissimilar in the alternative factor space. A canonical correlation analysis revealed a significant relationship between lizard morphology and habitat use. In general, large bulky lizards were associated with extensive vegetative cover while small slenderbodied lizards were found in open desert or grassland conditions. No significant relationship was found between community size and measures of niche overlap or species packing in either morphological or ecological space. A comparison of species packing between the field communities and randomly generated null communities revealed no significant overdispersion of the natural communities in either habitat use or morphology, thus providing no evidence to support the limiting—similarity hypothesis.