MOUNTAIN LIFE - Ontario | Winter 2016 - page 70

By Leslie Anthony
Being both a biologist
and an avid ski-tourer, I’d
seldom foundmyself skiing over the ice-covered
streams and ponds of Southern and Central
Ontario without giving thought to what lay
beneath—what it was like for animals that lived
in and around these water bodies to spend
such a large part of their existence entombed in
hibernation, and how they pulled it off. This was
particularly true of ectothermic (cold-blooded)
animals like reptiles and amphibians, whose
survival through Canada’s winters has proved a
science unto itself.
Animals employ two strategies in seasonally
cold climates: freeze avoidance and freeze
tolerance. The two share some biochemical and
physiological similarities, but whereas simple
avoidance (e.g., hibernating below the frost
line) is practiced by most animals, tolerance—
in which certain tissues actually freeze for
varying periods of time—is both rarer and
correspondingly more complex and interesting.
Kenneth B. Storey, professor of biochemistry at
Ottawa’s Carlton University, knows more about
the subject than anyone in the world. Among
those amphibians and reptiles he’s identified
as particularly freeze tolerant in Ontario are
Cope’s gray treefrog (
Hyla versicolor
), boreal
chorus frog (
Pseudacris triseriata
), spring peeper
Pseudacris crucifer
), wood frog (
Rana sylvatica
painted turtle (
Chrysemys pict
a), and common
gartersnake (
Thamnophis sirtalis
). The most
tolerant and best-studied of these is the wood
frog, which ranges to treeline in sub-arctic
regions of NorthAmerica. Storey conducted
much of the groundbreaking work on this
species over 20 years ago, and what he found
borders on incredible.
By hibernating on land, wood frogs become
active as soon as the snowmelts. Breeding
Thewood frog, the focus ofmuchof CarletonUniversity-basedKenneth Storey’s researchon the biochemistry of freeze tolerance.DANIELD’AURIAPHOTO.
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