Date: June 9, 2016
Source: Virginia Tech
A select group of garter snakes
can thank their ancestors for the ability to chow down on a poisonous newt and
live to tell the tale.
Common garter snakes, along with
four other snake species, have evolved the ability to eat extremely toxic
species such as the rough-skinned newt--amphibians that would kill a human
predator--thanks to at least 100 million years of evolution, according to Joel
McGlothlin, an assistant professor of biological sciences in the College of
Science and a Fralin Life Science Institute affiliate.
The nature of that evolution was
recently established by McGlothlin's team and will be published June 20 in the
journal Current Biology.
The international team of
researchers discovered that the ability to withstand the toxin that the newt
produces evolved following a 'building blocks' pattern, where an evolutionary
change in one gene can lead to changes in another.
In this case, over time, amino
acids in three different sodium channels found in nerves and muscle changed,
allowing select snakes to resist the numbness and paralysis typically brought
on by the toxin.
Resistant muscle gives snakes the
best protection against the newt's toxin, but there's a catch: resistant muscle
can only evolve in species that already have resistant nerves. McGlothlin's
team found that the ancestors of garter snakes gained toxin-resistant nerves
almost 40 million years ago.
"Garter snakes and newts are
locked in a coevolutionary arms race where as the newts become more toxic, the
snakes become more resistant," said McGlothlin, who is also affiliated
with the Global Change Center at Virginia Tech. "However, without the
leg-up provided by those resistant nerves, snakes wouldn't have been able to
withstand enough toxin to get this whole process started."
This arms race is most intense in
pocketed regions along the West Coast, where rough-skinned newts and garter
snakes co-exist.
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