page_title: Wood frog
section_title: Cold tolerance
hierarchical_section_title: Wood frog / Cold tolerance
caption_attribution_description: English: wood frog in Gatineau, Quebec
context_page_description: The wood frog has a broad distribution over North America, extending from the boreal forest of the north to the southern Appalachians, with several notable disjunct populations including lowland eastern North Carolina. The wood frog has garnered attention by biologists over the last century because of its freeze tolerance, relatively great degree of terrestrialism, interesting habitat associations, and relatively long-range movements.
  The ecology and conservation of the wood frog has attracted research attention in recent years because they are often considered "obligate" breeders in ephemeral wetlands that are themselves more imperiled than the species that breed in them. The wood frog has been proposed to be the official state amphibian of New York.
context_section_description: Similar to other northern frogs that enter dormancy close to the surface in soil and/or leaf litter, wood frogs can tolerate the freezing of their blood and other tissues. Urea is accumulated in tissues in preparation for overwintering, and liver glycogen is converted in large quantities to glucose in response to internal ice formation. Both urea and glucose act as cryoprotectants to limit the amount of ice that forms and to reduce osmotic shrinkage of cells.
  Frogs can survive many freeze/thaw events during winter if no more than about 65% of the total body water freezes. Wood frogs have a series of seven amino acid substitutions in the sarco/endoplasmic reticulum Ca²⁺-ATPase 1 (SERCA 1) enzyme ATP binding site that allows this pump to function at lower temperatures relative to less cold-tolerant species (e.g. Lithobates clamitans).
caption: Lithobates sylvaticus found in southern Quebec
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