. Advances in herpetology and evolutionary biology : essays in honor of Ernest E. Williams. Williams, Ernest E. (Ernest Edward); Herpetology; Evolution. 488 Advances in Herpetology and Evolutionary Biology Nevertheless, the actual diurnal variation in Tb in nature (Fig. 1) seems to be suffi- ciently large to affect sprint abilities of A. cristatellus. Whether this pattern is valid for other species and for other physio- logical activities of A. cristatellus re- mains to be determined. Data on thermal niche breadth are also relevant to an hypothesis (Tracy, 1979) concerning the relative degree
. Advances in herpetology and evolutionary biology : essays in honor of Ernest E. Williams. Williams, Ernest E. (Ernest Edward); Herpetology; Evolution. 488 Advances in Herpetology and Evolutionary Biology Nevertheless, the actual diurnal variation in Tb in nature (Fig. 1) seems to be suffi- ciently large to affect sprint abilities of A. cristatellus. Whether this pattern is valid for other species and for other physio- logical activities of A. cristatellus re- mains to be determined. Data on thermal niche breadth are also relevant to an hypothesis (Tracy, 1979) concerning the relative degree of physio- logical specialization for temperature in frogs versus lizards. Because high rates of evaporative water loss hinder the ability of many frogs to control T^ by basking (Tracy, 1976), selection might have favored a relatively temperature- independent physiology in frogs. Indeed, data on the thermal performance breadths (80% level) for Rana clamitans (Huey and Stevenson, 1979) and for Anolis cristatellus (° and °C, respectively), are in accord with Tracy's (1979) prediction. Interestingly, even though the thermal performance breadths of Rana and Anolis differ strikingly (), the tolerance ranges for these two species are similar {Rana = °C, Anolis = °C). This observation supports the argument that selection for tolerance range may be independent of that for thermal perform- ance breadth (Huey and Stevenson, 1979; Huey, 1982). DISCUSSION If the preferred temperatures of lizards reflect underlying physiological per- formance (Dawson, 1975), then A. crist- atellus in open habitats might have a physiological advantage over "forest" lizards in the morning; but "forest" liz- ards might have an advantage at midday. On the other hand, if some aspects of physiology are relatively independent of T^^ near the thermal preferendum (see Bennett, 1980), then the observed varia- tions in T^ (Fig. 1) oi Anolis cristatellus might not be of suffi
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Keywords: ., bookauthorharvarduniver, bookcentury1900, booksubjectherpetology
