Thermoregulation in Desert Lizards Essay Example | Topics and Well Written Essays - 1000 words

Thermoregulation in Desert Lizards - Essay Example Among ectotherms, lizards inhabiting tropical regions are most likely to be affected since biodiversity in their habitats are most affected (Meek 1). Change in temperatures affects lizards in terms of thermoregulation mechanisms, energy expenditure, as well as biological activity. Investigation on how temperature changes, caused by global warming, are affecting lizards is of utmost importance especially considering that lizards are at a high risk of extinction. According to Huey et al, â€Å"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† (Huey et al 1939-1940). This paper explores the effect of global warming on thermoregulation mechanisms of lizards. Strategies to Thermoregulation of Desert Lizard According to theories of evolution, thermoregulatory mechanisms in many species especially reptiles has evolved wit h time in response to changing climatic conditions (Huey et al 1939-1942). Changes in climatic conditions cause increase in temperature variations forcing lizards to adopt both biological and behavioral temperature regulation mechanisms in order to cope with changing weather conditions. According to Meek, â€Å"The evolution of thermoregulatory behavior in reptiles almost certainly arose because environments are not usually thermally stable but fluctuate both on a daily or seasonal basis or because of uneven heat distributions within environments† (Meek 1). Meek hypothesized that any thermoregulation mechanism adopted by lizards comes at costs and benefits. For instance, lguanid lizard inhabiting high altitudes where temperatures are extremely low use ground vegetation for insulation. It was observed that the lizards could raise their body temperature to approximately 35degrees by basking on the sun for two hours. They could then return to their shelters and maintain their bo dy temperature for the whole afternoon. However, such a thermoregulatory mechanism comes at a cost since the lizards remain inactive, minimal habitat utilization, and increased basking (Meek 1). These findings correlate with findings by Kearney et al â€Å"Warmer environments also may increase maintenance energy costs while simultaneously constraining activity time, putting pressure on mass, and energy budgets† (Kearney et al 1). One of behavioral mechanisms adopted by lizard is change of body color in relation to surrounding environment temperatures. According to Bradshaw, this type of behavior enables the desert lizard to maintain its body temperature in a normal range. As the temperature goes down the lizard turns into black. Black color is a good absorber of heat and hence it is able to absorb heat faster from the environment. Once the environmental temperature rises, light color becomes prominent. This turns the heat away and enables the lizard to cool its body. This exp lains why desert lizards are light in color as compared to lizards in cold regions (Bradshaw 90). Besides being a thermoregulatory mechanism, a study by Bujes and Verrastro found out that color change was also found to be a camouflage mechanism (Bujes and Verrastro 1). Activity of the Lizard in Different Seasons The most important factor in behavioral regulation of temperature in desert lizards is use of burrows. Indeed, different studies have pointed to the same fact that desert lizards spend almost 75% of their lifetime in burrows throughout annual season. These burrows offer temporary rescue or long-term survival mechanism. Lizards either dig their own burrows or use already existing ones (Bradshaw 166). Similar findings were found by â€Å"The activity of