Desert Lizard Diversity: Additional Comments and Some Data

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Abstract
A complex mega-hypothesis invoking multiple causality was recently proposed to explain the high diversity of lizards in arid Australia (Morton and James 1988). Putative causal links in its intricate scheme are evaluated, and some data are presented that can be brought to bear on the problem. Although many links in the causal network appear fairly well established, some are weak. Evidence that Australian soils are infertile is less than compelling. Chenopod-shrub sites do not necessarily support impoverished termite faunas, as had been predicted; a chenopod site in the Kalahari had the highest termite diversity of 10 study areas. Moreover, termites dominate the diets of Kalahari lizards and appear to be more abundant in the Kalahari semi-desert than in Australian deserts. A greater percentage of lizard species specialize on termites in the Kalahari than in Australia. A fire-succession cycle is quite important in spinifex habitats in Australia, generating a mosaic of habitats with differing degrees of openness at various post-fire ages; this greatly enhances lizard diversity. Fires may reticulate more in inland Australia than in grassland regions in other parts of the world. Satellite imagery can be used to examine and quantify fire geometry. Fires, and fire-generated spatial heterogeneity, should be added to the list of physical factors driving the desert-lizard system. Historical and biogeographic phenomena must be better integrated into attempts to explain differences in diversity between geographical regions.