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On the climatic determination of scale size in a lizard.

abstract1 (full description below): Systematic Zoology 21:97-105.
Climactic Scale Size Lizard. PDF/Acrobat file     On the climatic determination of scale size in a lizard.

Abstract The relation between climate and scale size was studied in the two northern groups of Sceloporus grociosus. In the western section, an area of intense summer drought, 84 percent of the geographic variation in the number of mid-dorsal scales was explained in a multiple regression model by August rainfall and annual pan evaporation. Desiccation is probably the relevant selective factor. In the eastern section where the summer drought is variably ameliorated by the summer Sonoran monsoon rains, especially in the south, winter maximum temperatures and August rainfall, in that order of importance, account for 83 percent of the geographic variation. It is hypothesized that scale size, by partially determining cutaneous surface area, is an important component of both thermoregulatory and water balance systems in this animal. [Scale size; lizards; Sceloporus; multiple regression.]