Huey R.B.

behavioral thermoregulation in lizards: importance of associated costs

Raymond B. Huey
Behavioral Thermoregulation in Lizards: Importance of Associated Costs
Science 31 May 1974:
Vol. 184 no. 4140 pp. 1001-1003
DOI: 10.1126/science.184.4140.1001

The Puerto Rican lizard Anolis cristatellus behaviorally regulates body temperature in an open habitat but passively tolerates lower and more variable temperatures in an adjacent forest where basking sites are few and distant. Thermoregulation may be adaptive only when costs resulting from associated losses of time and energy are low.

Thermal Biology of Anolis Lizards in a Complex Fauna: The Christatellus Group on Puerto Rico

Thermal Biology of Anolis Lizards in a Complex Fauna: The Christatellus Group on Puerto Rico
Raymond B. Huey and T. Preston Webster
Vol. 57, No. 5 (Late Summer, 1976), pp. 985-994

To describe the thermal biology of the three trunk-ground species of the Anolis cristatellus group on Puerto Rico, an island with 10 species of Anolis, we obtained samples of air and body temperatures of A. gundlachi (shady perches, montane forests), A. cristatellus (shady or sunny perches in open or closed forests, lowlands to mid-elevations), and A. cooki (sunny perches in open, xeric lowlands). Average body temperatures parallel altitudinal and habitat association (lowest for A gundlachi, highest for A. cooki). Within a species, body temperatures are strongly correlated with air temperatures and thus vary with altitude, time of day, habitat, and weather. Observed differences between sympatric species in body temperatures and habitat probably reflect physiological requirements, but may be magnified by competition. Relative thermal niche breadth of individuals of these species is approximated and compared with data on species from simple anole faunas to evaluate hypotheses on the evaluation of thermal niche breadth. Extent of basking behavior is inversely related to associated costs for these species. In closed forests where costs of raising body temperatures are high, A. gundlachi and A. cristatellus rarely bask and seemingly are routinely passive to ambient conditions. In open habitats where costs are low, A. cristatellus and A. cooki frequently bask.

Why tropical forest lizards are vulnerable to climate warming

Huey, R.B. et al. (2009) Why tropical forest lizards are vulnerable to
climate warming. Proc. R. Soc. Lond., B, Biol. Sci. 276, 1939–1948

Biological impacts of climate warming are predicted to increase with latitude, paralleling increases in warming. However, the magnitude of impacts depends not only on the degree of warming but also on the number of species at risk, their physiological sensitivity to warming and their options for behavioural and physiological compensation. Lizards are useful for evaluating risks of warming because their thermal biology is well studied.We conducted macrophysiological analyses of diurnal lizards from diverse latitudes plus focal species analyses of Puerto Rican Anolis and Sphaerodactyus. Although tropical lowland lizards live in environments that are warm all year, macrophysiological analyses indicate that some tropical lineages (thermoconformers that live in forests) are active at low body temperature and are intolerant of warm temperatures. Focal species analyses show that some tropical forest lizards were already experiencing stressful body temperatures in summer when studied several decades ago. Simulations suggest that warming will not only further depress their physiological performance in summer, but will also enable warm-adapted, open-habitat competitors and predators to invade forests. Forest lizards are key components of tropical ecosystems, but appear vulnerable to the cascading physiological and ecological effects of climate warming, even though rates of tropical warming may be relatively low.
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