Biophysical Ecology and Pattern Recognition
This study was undertaken to investigate behavioral adaptations of a lizard, Lacertilia, to its environment. Twelve peeps, representing the lizards, were placed in a habitat with two microhabitats of different temperatures. Six peeps were placed in one microhabitat, and six in the other. The internal temperature of these “lizards” was measured over a period of 20 minutes to see if their body temperatures matched that of their environment and to make inferences about the behavioral adaptations the organism might acquire to maintain its body temperature. One microhabitat was on a tree and under the branches; the other was at the base of the tree. We hypothesized that the microhabitat in the branches of the tree would be cooler, and at the base of the tree would be warmer. The average body temperature was higher in the warmer microhabitat, and lower in the cooler microhabitat, which supports our hypothesis. Under the tree branches, the peeps were exposed to increased convection and decreased radiation. At the base of the tree, the peeps were exposed to increased radiation and conduction. Introduction:
Habitat temperature differences are a major focus in ecology because it impacts the organism’s ability to perform tasks. Biophysical ecology involves the behavior and morphologies of organisms and how that might alter the temperature of their bodies. Understanding mechanisms that control body temperatures of ectotherms is an important part of population ecology. Body temperature determines sprint speeds of snakes and lizards, flying abilities of insects, survival rates of interdal organisms, and rates of water loss in plants (Course Material). Ectotherms are organisms that resemble their environment in terms of body temperature, and unlike endotherms, do not use metabolic processes to control their body temperature. Ectotherms’ body temperature depends on their surrounding thermal environment and the relationship between their body temperature and environmental inputs and outputs is easier to manipulate. Organisms have behavioral adaptations to their environment in order to reduce physiological costs, and these adaptations depend on the thermal environment that the organism is located. Organisms change their behavior according to which habitat or microhabitat it chooses to inhabit and this affects its body temperature without changing its morphology. The heat budget of an organism shows how heat is gained or lost when these adaptations are incorporated. The heat budget equation is: Change in heat content = metabolism – evaporation +/- convection +/- conduction +/- radiation. Radiation is the absorption of radiative energy. Convection is the transfer of heat to or from a moving fluid. Conduction is the transfer of heat to or from a solid surface, and evaporation is the transfer of heat to the conversion of water from liquid to gas phase (Course Material). In this study, the internal temperature of an organism was measured over a period of time in two different habitats to investigate behavioral adaptations of the organism to its environment. We expected that our organism would go up in the tree (our first microhabitat) to get cool, and go to the base of the tree (our second microhabitat) to get warmer. When the lizard wants to be warm, it sees that the base of the tree is directly in the sunlight, and conduction between the already warm ground and the lizards body will make the lizard warm. If it becomes too hot, the lizard will retreat up into the tree under the branches where it knows there is shade and convection from the wind at that elevation. Materials and Methods:
Planning the experiment in the field
A bag of lab materials was obtained from the TA which included scissors, string, tape, and materials that could be used to manipulate each habitat and place the organisms in each habitat. Groups then decided on two habitats that each included two microhabitats to...
Cited: Gunderson, AR., Leal, M. 2012. Geographic variation in vulnerability to climate warming in a tropical Caribbean lizard. Functional Ecology. Volume: 26. Pages 783-793.
Kearney, M., Porter, WP. 2004. Mapping the fundamental niche: Physiology, climate, and the distribution of a nocturnal lizard. Ecology. Volume: 85. Pages 3119-3131.
Course Material. Thermal Environments: Pattern Recognition and Experimental Design. Fall 2012.
Microsoft Excel. Mac 2012
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