Literaturdatenbank
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Edwards, A. (2005). Using painted turtles (chrysemys picta) to test the cost benefit model of thermoregulation. Unpublished thesis , University of Ottawa.
Added by: Sarina Wunderlich (25 Jan 2011 10:31:58 UTC) |
| Resource type: Thesis/Dissertation BibTeX citation key: Edwards2005 View all bibliographic details  |
Categories: General Keywords: Chrysemys, Chrysemys picta, Emydidae, Habitat = habitat, Nordamerika = North America, Physiologie = physiology, Schildkröten = turtles + tortoises Creators: Edwards Publisher: University of Ottawa |
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| Abstract |
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Body temperature affects nearly all processes of ectotherms. Reptiles do not generate sufficient heat to internally regulate their body temperature. Consequently, body temperature is regulated behaviourally. The extent to which reptiles regulate body temperature, however, varies greatly. The Huey and Slatkin (1976) cost benefit model of thermoregulation has been used to predict thermoregulatory investment. The cost benefit model predicts that individuals should thermoregulate more precisely when the costs of thermoregulation are low. The costs of thermoregulation are low when the thermal quality of the habitat is high. To test this prediction, I took 31,297 internal body temperature (Tb) measurements from 18 midland painted turtles (Chrysemys picta marginata) throughout their active season in a marsh in eastern Ontario. I derived operative environmental temperatures (Te) from physical models and water temperatures. I measured the preferred body temperature range (Tset) of painted turtles in a thermal gradient. Tset was 21.3oC to 25.0oC. I used Tb, Te, and Tset to calculate thermoregulation indices (Ex and de-db) to quantify the extent of thermoregulation. Ex = 40.7% and de-db = 2.4oC. Both values indicated that painted turtles are moderate thermoregulators, despite inhabiting a high cost, low thermal quality environment. Effort to regulate body temperature increased as the thermal quality of the habitat decreased. Thermoregulatory effort was higher when Tset could not be achieved than when it could. I detected, seasonal differences in thermoregulation. In early season, C. picta thermoregulated to a greater extent than in mid season and late season. These results indicated that the disadvantages of thermoconformity are greater than heretofore recognized and that the cost-benefit model of thermoregulation must be revised.
Added by: Sarina Wunderlich |