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Pregnant Lizards Exposed to Rapid Environmental Warming
Lopez-Alcaide, S., Nakamura, M., Macip-Rios, R. and Martinez-Meyer, E. 2014. Does behavioral thermoregulation help pregnant Sceloporus adleri lizards in dealing with fast environmental temperature rise? Herpetological Journal 24: 41-47.

The authors write that "in closely related species of reptiles, basic biological and ecological mechanisms such as feeding, water balance and breeding usually occur at similar ranges of field body temperature (Tb) regardless of deviating ambient temperatures" in a phenomenon known as conservative thermal physiology, which has been well described over a period of several decades by Bogert (1949), Bowker (1993), Seebacher and Shine (2004) and Glanville and Seebacher (2006).

What was done
In order "to test the idea that pregnant lizards adjust their thermoregulatory behavior to rising temperatures," in the words of Lopez-Alcaide et al., they "set up an experiment with 40 pregnant Sceloporus adleri and measured daily activity and basking time at different treatments (22, 24, 26, and 28°C) for six consecutive days."

What was learned
The four Mexican researchers found that (1) "basking time significantly decreased with increasing temperature," that (2) "lizards were more active in the earliest two time periods of the day (0800-1030 and 1030-1300 hours) when compared to later hours (1530-1800) for all treatments," that (3) "pregnant females of S. adleri showed similar preferred body temperature across thermal treatments," and that (4) "Tb was almost identical to the temperature recorded in the field for other viviparous Sceloporus species," as had been seen in the earlier studies of Beuchat (1988) and Mathies and Andrews (1997).

What it means
Lopez-Alcaide et al. conclude their study by saying their results suggest that "pregnant S. adleri females achieved their preferred body temperature through behavioral thermoregulation even when temperatures rose by 6°C (as observed by Hertz, 1981; Stevenson, 1985; van Damme et al., 1987; Adolph, 1990; Bauwens et al., 1996; Diaz, 1997)." And they add that their study also suggests that "pregnant S. adleri females are able to adjust their behavioral thermoregulation to different thermal environments in a short enough period of time to maintain an adequate body temperature for key physiological processes such as development and growth of their offspring."

Adolph, S.C. 1990. Influence of behavioral thermoregulation on microhabitat use by two Sceloporus lizards. Ecology 71: 315-327.

Bauwens, D.P., Hertz, H. and Castilla, A.M. 1996. Thermoregulation in lacertid lizard: The relative contributions of distinct behavioral mechanisms. Ecology 77: 1818-1830.

Beuchat, C.A. 1988. Temperature effects during gestation in a viviparous lizard. Journal of Thermal Biology 13: 135-142.

Bogert, C.M. 1949. Thermoregulation in reptiles, a factor in evolution. Evolution 3: 195-211.

Bowker, R.G. 1993. The thermoregulation of the lizards Chenimodophours exsanguis and C. velox: Some consequences of high body temperature. In: Wright, J.W. and Vitt, L.J. (Eds.). Biology of the Whiptail Lizards (Genus Cnemidophorus). Oklahoma University Press, Norman, Oklahoma, USA, pp. 117-132.

Diaz, J.A. 1997. Ecological correlates of the thermal quality of an ectotherm's habitat: a comparison between two temperate lizard populations. Functional Ecology 11: 79-89.

Glanville, E.J. and Seebacher, F. 2006. Compensation for environmental change by complementary shifts of thermal sensitivity and thermoregulatory behavior in an ectotherm. Journal of Experimental Biology 209: 4869-4877.

Hertz, P.E. 1981. Adaptation to altitude in two West Indian anoles (Reptilia. Iguanidae): field thermal biology and physiological ecology. Journal of Zoology 195: 25-37.

Mathies, T. and Andrews, R.M. 1997. Influence of pregnancy on the thermal biology of the lizard, Sceloporus jarrovi: why do pregnant females exhibit low body temperatures? Functional Ecology 11: 498-507.

Seebacher, F. and Shine, R. 2004. Evaluating thermoregulation in reptiles: the fallacy of the inappropriately applied method. Physiological and Biochemical Zoology 77: 688-695.

Stevenson, R.D. 1985. The relative importance of behavioral and physiological adjustments controlling body temperature in terrestrial ectotherms. American Naturalist 126: 362-386.

Van Damme, R., Bauwens, D. and Verheyen, R.F. 1987. Thermoregulatory responses to environmental seasonality by the lizard Lacerta vivipara. Herpetologica 43: 405-415.

Reviewed 23 July 2014