Comparative Analysis of Spatial Organization of Desert Lizard Communities in Middle Asia and Mexico

We analyze the spatial organization of two lizard communities from the Turan (Bukhara) and Chihuahua (Mapimi) deserts by the use of canonical (discriminant function) analysis. Twenty-three variables of the environment (soil structure, vegetation) were considered. The number of species in both communities are similar (13 in Bukhara and 14 in Mapimi), but the mean densities of most populations in Mapimi are four times lower than in Bukhara. Half of Mapimi's species are rare (1-4 ind ha-1) and maximum densities are 18-27 ind ha-1. Mean densities of most Bukhara species are at the level of 20-40 ind ha-1 and densities of most abundant species are 80-120 ind ha-1. In spite of these differences the lizard community biomasses in both localities are similar. The ecological niches of lizards in both communities distribute along two main ecological axes. The first axis represents the gradient of soil structure from sand to clay; the second axis represents the gradient of protective conditions (percent of vegetation cover, number of rodent burrows). In the Mapimi community the distribution of niches is even, whereas there are two distinct spatial guilds in Bukhara consisting of psammophilous and sclerophilous species. The niche overlap in Mapimi is lower than in Bukhara. There is a negative correlation between the niche breadth and the distance from the center of the resource space. At the same time there are no correlations between species abundance, niche breadth and niche position in the resource space. We discuss the problem of elucidating the eco-equivalent species at the inter-continental comparison.