The Mountain Tailed Frog, Ascaphus montanus is a cryophile that is associated with permanent mountain streams in the Northwestern United States. Although unknown, adults likely overwinter in the fast moving streams, but to do so they would need to survive extended bouts of subzero temperatures. Previous work has described the frog’s ability to supercool to low temperatures and survive freezing. The purpose of this study was to determine tissue level indicators of freeze tolerance, namely cryoprotectant concentrations and wet mass. Winter acclimated frogs cooled from 2°C at 0.2°C h-1 and then held at -1°C until they spontaneously froze or had a small ice chip placed on their pack to inoculate freezing after 3 days. After being held at -1 °C for seven days, they were then removed, double pithed and the gracilis and gastrocnemius muscles, heart, and liver were removed on ice. Water content of the liver was determined after a portion of the tissue was blotted dry, weighed and dried in an oven at 60 C°. Water content significantly increased after freezing. Urea and Glycerol concentration were below detectable limits of the assay. Glucose concentrations did not change in response to freezing but were elevated compared to acclimatized individuals of other species. Based on the known literature and previous work it seems that this species can survive in high sub-zero temperatures found in its aquatic environment. These data suggest that the frogs may survive freezing in conditions likely found in their stream habitat and may use a combination of supercooling and freeze tolerance to overwinter.
|Advisor:||Williams, Jason B., Essner, Richard L.|
|Commitee:||Jennings, David H.|
|School:||Southern Illinois University at Edwardsville|
|School Location:||United States -- Illinois|
|Source:||MAI 55/03M(E), Masters Abstracts International|
|Subjects:||Ecology, Zoology, Physiology|
|Keywords:||Ascaphus, Frog, Montanus, Mountain, Overwintering, Rocky, Tailed|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be