The work described in this thesis has been carried out over the period 1958-1965, having been begun during the tenure of a residency at the University of Colorado, Denver, U.S.A. At this time, surgery for the closure of septal defects was being actively carried out, and interest was aroused, in two clinical features which were apparent from close contact with this programme. The first was the nature of the chest deformities associated with septal defects; the second, the striking alleviation of symptoms which followed successful closure of these defects. The reasons for these phenomena were by no means clear and the subsequent work has been concerned with an attempt to understand them.

Ectotherms regulate body temperature (Tb) primarily through behavioral interactions with their environment. These animals also have limited aerobic scopes and must rely on anaerobic metabolism to support intense activity; lactate byproduct and glycogen depletion are two consequences of anaerobic metabolism that must be dealt with during exercise recovery. It has been suggested that, in many ectothermic species, Tb may affect the rate of lactate clearance and glycogen repletion during recovery from intense exercise. This study investigated thermoregulatory behavior in Western Fence Lizards (Sceloporus occidentalis) to determine preferred Tb during exercise recovery. I hypothesized that animals would select higher Tb’sduring the recovery period on the basis that biochemical processes occur at faster rates at high temperatures, which may facilitate a more rapid reduction of lactate and replenishment of glycogen stores. However, it was found that control animals maintained a constant Tb of 33°C, while exercised animals cooled Tb to 30°C 20 minutes after exercising, and eventually warmed to 32°C by the 2 hour mark. Animals were found to be able to cool Tb by a maximum of 0.175°C/min given the available temperatures, which negated possible effects of temperature variation on Tb during exercise trials and transport. My results suggest a benefit of lowered Tb to facilitate exercise recovery in these animals. Behavioral hypothermia in S. occidentalis may be caused by physiological triggers associated with intense activity such as hypoxia, hypercapnia, or elevated blood lactate concentration. However, these speculations must be confirmed by further research.

Thesis (Ph. D.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains xii, 278 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references.

Thesis (Ph. D.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains xiv, 155 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references.

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