185. Pianka, E. R. 1966. Convexity, desert lizards, and spatial 

 heterogeneity. ECOLOGY ^7(6): 1055-1059. 



Ten flatland desert sites were studied from southern Idaho to 

 southern Arizona. The number of lizard species present in each area 

 was correlated with horizontal and vertical components of spatial he- 

 terogeneity (vegetation and possibly substrate). Each area had from 

 ^ to 10 species, increasing from north to south, out of a possible 

 total of 12. Convexity is defined as the sum total of variables re- 

 garding food preferences, substrate characteristics, and foraging be- 

 havior. Cnemidophorus tigris is the only teiid represented; it ex- 

 ploits the environment by constantly moving from cover to cover, paus- 

 ing occasionally to dig or climb for prey. It is the only widely fo- 

 raging diurnal species in this system, and is thus the most "convex". 



186. — . 1967. On lizard species diversity: North American flatland 

 deserts. ECOLOGY 48(3): 333-351. 



This study encompassed the Great Basin, Mojave and Sonoran 

 deserts; Cnemidophorus tigris was the only teiid present. Eight 

 mechanisms for the determination of species diversity using lizards 

 are examined. It is concluded that ecological time, spatial hetero- 

 geneity, length of growing season, and amount of warm season produc- 

 tivity are all pertinent factors, but that the most important single 

 factor is spatial heterogeneity (mainly vegetative) of the environment. 

 It is suggested that climatic variability allows the coexistence of 

 many different plant life forms, the variety of which in turn controls 

 the number of lizard species present. This study spotlights the lack 

 of same in New Mexico where lizards, particularily the genus Cnemido - 

 phorus , are very diverse in desert environments (opinion of this re- 

 viewer). 



187. — . 1970. Comparative autecology of the lizard Cnemidophorus 

 tigris in different parts of its geographic range. ECOLOGY 51: 703-20. 



The subspecies tigris , gracilis and aethiops were studied from 

 southern Idaho through northern Sonora. Lizards in the north emerge in 

 May and aestivate during midsummer months; those in the south are ac- 

 tive from April through late August. Daily activity periods are simi- 

 lar for all populations studied, although time of emergence tends to be 

 later in the north. Daily patterns are bimodal with much more activity 

 in the morning than the afternoon. There is a significant positive 

 correlation between estimated lizard abundances and total precipitation 

 during the previous 5 years, suggesting that abundance is correlated 

 with food supply. There is a latitudinal cline exhibited in mean body 

 temperature of active lizards; lizards of northern populations are ac- 



