Literaturdatenbank
Literaturdatenbank |
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Packard, G. C. (1996). Interpopulational variation in the cold-tolerance of hatchling painted turtles. Journal of Thermal Biology, 21(3), 183–190.
Added by: Admin (23 Aug 2008 15:33:07 UTC) |
| Resource type: Journal Article BibTeX citation key: Packard1996 View all bibliographic details  |
Categories: General Keywords: Chrysemys, Chrysemys picta, Emydidae, Habitat = habitat, Nordamerika = North America, Schildkröten = turtles + tortoises, Zeitigung = incubation Creators: , Packard Collection: Journal of Thermal Biology |
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| Abstract |
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Abstract We studied hatchling painted turtles (Chrysemys picta) from northern Illinois to determine whether animals from this region withstand exposure to subzero temperatures during winter by tolerating freezing or by avoiding freezing. Turtles that were isolated from all contact with ice supercooled quite readily to - 6°C. However, animals began to freeze spontaneously between - 6° and - 8°C, thereby indicating that a heterogeneous nucleator was present in body fluids to initiate freezing over this limited range of temperature. Hatchlings that came into contact with crystals of ice sometimes were caused to freeze by inoculation at temperatures above the limit for supercooling. However, many turtles were not inoculated, so their integument seemingly resisted the penetration of ice into body compartments from the environment. Animals that froze did not survive exposure to cold, and animals that survived did not freeze. Thus, the adaptive strategy exploited by hatchling painted turtles overwintering in northern Illinois apparently is to sustain a state of supercooling and to remain unfrozen. The heterogeneous nucleator in body fluids set an absolute limit for cold-tolerance in these animals at about - 8°C. Thus, hatchlings from Illinois seem to be less tolerant of cold than hatchlings from Nebraska, despite the fact that neonates from both localities exploit the same basic mechanism for surviving at subzero temperatures.
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