Geographic divergence and colour change in response to visual backgrounds and illumination intensity in bearded dragons.

Animals may improve camouflage by both dynamic colour change and local evolutionary adaptation of colour but we have little understanding of their relative importance in colour-changing species. We tested for differences in colour change in response to background colour and light intensity in two populations of central bearded dragon lizards () representing the extremes in body coloration and geographical range. We found that bearded dragons change colour in response to various backgrounds and that colour change is affected by illumination intensity.

Color Change for Thermoregulation versus Camouflage in Free-Ranging Lizards.

Animal coloration has multiple functions including thermoregulation, camouflage, and social signaling, and the requirements of each function may sometimes conflict. Many terrestrial ectotherms accommodate the multiple functions of color through color change. However, the relative importance of these functions and how color-changing species accommodate them when they do conflict are poorly understood because we lack data on color change in the wild.

Seasonal reproductive endothermy in tegu lizards.

With some notable exceptions, small ectothermic vertebrates are incapable of endogenously sustaining a body temperature substantially above ambient temperature. This view was challenged by our observations of nighttime body temperatures sustained well above ambient (up to 10°C) during the reproductive season in tegu lizards (~2 kg). This led us to hypothesize that tegus have an enhanced capacity to augment heat production and heat conservation.

Cyclic colour change in the bearded dragon Pogona vitticeps under different photoperiods.

The ability to change colour rapidly is widespread among ectotherms and has various functions including camouflage, communication and thermoregulation. The process of colour change can occur as an aperiodic event or be rhythmic, induced by cyclic environmental factors or regulated by internal oscillators. Despite the importance of colour change in reptile ecology, few studies have investigated the occurrence of a circadian rhythm in lizard pigmentation.

Evaporative respiratory cooling augments pit organ thermal detection in rattlesnakes.

Rattlesnakes use their facial pit organs to sense external thermal fluctuations. A temperature decrease in the heat-sensing membrane of the pit organ has the potential to enhance heat flux between their endothermic prey and the thermal sensors, affect the optimal functioning of thermal sensors in the pit membrane and reduce the formation of thermal "afterimages", improving thermal detection. We examined the potential for respiratory cooling to improve strike behaviour, capture, and consumption of endothermic prey in the South American rattlesnake, as behavioural indicators of thermal detection.

Heat loss may explain bill size differences between birds occupying different habitats.

Background: Research on variation in bill morphology has focused on the role of diet. Bills have other functions, however, including a role in heat and water balance. The role of the bill in heat loss may be particularly important in birds where water is limiting.

The effect of thermal quality on the thermoregulatory behavior of the bearded dragon Pogona vitticeps: influences of methodological assessment.

Metabolic functions are generally optimized within a narrow range of body temperatures (T(b)'s), conferring thermoregulation great importance to the survival and fitness of an animal. In lizards, T(b) regulation is mainly behavioral, and the metabolic costs associated with behavioral thermoregulation are primarily locomotory. In reptiles, however, it has been proposed that they thermoregulate less precisely when the associated costs, metabolic or otherwise, are high.

Decreased precision contributes to the hypoxic thermoregulatory response in lizards.

The decrease in body temperature (T(b)) observed in most vertebrate classes in response to hypoxia has been attributed to a regulated decrease in set-point, protecting organs against tissue death due to oxygen depletion. Hypoxia, however, imparts particular challenges to metabolic function which may, in turn, affect thermoregulation. In ectotherms, where thermoregulation is mainly behavioural, stressors that influence the propensity to move and respond to temperature gradients are expected to have an impact on thermoregulatory control.

Body temperature depression and peripheral heat loss accompany the metabolic and ventilatory responses to hypoxia in low and high altitude birds.

The objectives of this study were to compare the thermoregulatory, metabolic and ventilatory responses to hypoxia of the high altitude bar-headed goose with low altitude waterfowl. All birds were found to reduce body temperature (T(b)) during hypoxia, by up to 1-1.5 degrees C in severe hypoxia.

Respiratory cooling and thermoregulatory coupling in reptiles.

Comparative physiological research on reptiles has focused primarily on the understanding of mechanisms of the control of breathing as they relate to respiratory gases or temperature itself. Comparatively less research has been done on the possible link between breathing and thermoregulation. Reptiles possess remarkable thermoregulatory capabilities, making use of behavioural and physiological mechanisms to regulate body temperature.