FREEZING SURVIVAL OF THE GARTER SNAKE THAMNOPHIS-SIRTALIS-PARIETALIS

Citation
Ta. Churchill et Kb. Storey, FREEZING SURVIVAL OF THE GARTER SNAKE THAMNOPHIS-SIRTALIS-PARIETALIS, Canadian journal of zoology, 70(1), 1992, pp. 99-105
Citations number
29
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Zoology
Journal title
ISSN journal
0008-4301
Volume
70
Issue
1
Year of publication
1992
Pages
99 - 105
Database
ISI
SICI code
0008-4301(1992)70:1<99:FSOTGS>2.0.ZU;2-C
Abstract
Cold hardiness was evaluated for the red-sided garter snake, Thamnophi s sirtalis parietalis. Snakes collected in the autumn near communal de n sites showed an ability to supercool (Supercooling point, SCP = -5.5 -degrees-C). However, by midwinter, supercooling capacity was reduced and snakes cooled only to -0.8 to - 1.2-degrees-C before freezing. Sur vival of freezing and body ice contents were determined over a time co urse of freezing exposure at -2.5-degrees-C. Snakes recovered fully af ter freezing exposures of 3 h or less that produced ice contents of up to 40% of total body water. After longer periods and with ice content s of over 50%. survival was reduced. Only 50% of snakes survived 10 h of freezing and no snakes recovered after 24 or 48 h with a maximal ic e content of 70% of body water. Putative cryoprotectants were assessed in seven organs (liver, kidney, muscle, intestine, brain, tung, heart ) as well as the eggs after 5 h of freezing at -2.5-degrees-C. Glucose content increased 4-fold in liver, and lactate rose by 50% in heart, but levels of these and other possible cryoprotectants did not increas e in other organs during freezing. However, a high free amino acid poo l, including 14-24-mu-mol/g wet weight taurine, was present in the org ans. The data suggest that long-term freezing survival is not part of the winter hibernation strategy of this species, but tolerance of brie f freezing exposures may be adaptive in dealing with overnight frosts when the animals are active above ground.