Blue-tongue vs red-bellied black: An Australian evolutionary arms race


Date:
September 7, 2021
Source:
University of Queensland
Summary:
Scientists have discovered that the humble blue-tongue lizard is
largely resistant to the venom of the deadly red-bellied black
snake, while giant carnivorous monitor lizards which feed on
Australia's most venomous snakes are not.



FULL STORY ========================================================================== Scientists have discovered that the humble blue-tongue lizard is
largely resistant to the venom of the deadly red-bellied black snake,
while giant carnivorous monitor lizards which feed on Australia's most
venomous snakes are not.


==========================================================================
The surprising finding was revealed after University of Queensland
scientists compared the effects of various reptile blood plasmas when
exposed to the venom.

UQ PhD candidate Nicholas Youngman said mammalian -- and particularly,
human - - reactions had been heavily investigated, but very little was
known about snake venom effects on other reptiles.

"It was a shock discovering that the eastern blue-tongue, along with the shingleback, showed resistance specifically to red black snake venom,"
Mr Youngman said.

"Since their resistance was so specific to only this snake species, it
seems these lizards have evolved a special plasma component -- known as
a serum factor -- in their blood.

"This prevents specific toxins in red-bellied black snake venom from
clotting the lizards' plasma, which would lead to a rapid death in most
other animals.



========================================================================== "This resistance doesn't mean they're completely immune, but it would give
them a greater chance of survival, allowing them to escape or fight back.

"Much like how a COVID-19 vaccine doesn't mean you don't get sick at all,
it just means you are less likely to die." The research team analysed
the effects of seven different Australian snake venoms on the plasma of
two species of blue-tongued skinks and three species of monitor lizards
that would interact with these snakes in the wild.

Associate Professor Bryan Fry, who heads UQ's Venom Evolution Lab,
said the results also revealed that monitor lizards -- or goannas --
were not resistant to the snake venoms.

"You'd think that a goanna would be significantly resistant to the
venom of any snake it was hunting and eating, but that isn't the case,"
Dr Fry said.

"Snake venom can only cause harm to goannas if it's injected into its
body by the snake's fangs, it can't be absorbed directly through the skin.

"Goannas are heavily armoured and their scales act like medieval chain
mail, with each containing a piece of bone, meaning venomous snakes'
fangs struggle to pierce this armour.

"So -- unlike the slow, vulnerable blue-tongue lizard -- there's no
pressure for goannas to evolve resistance; natural selection has invested
in their armour and it's clearly working for them.

"These two divergent forms of resistance
are fascinating examples of evolutionary novelty." ========================================================================== Story Source: Materials provided by University_of_Queensland. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Nicholas J. Youngman, Joshua Llinas, Bryan G. Fry. Evidence for
Resistance to Coagulotoxic Effects of Australian Elapid Snake Venoms
by Sympatric Prey (Blue Tongue Skinks) but Not by Predators (Monitor
Lizards). Toxins, 2021; 13 (9): 590 DOI: 10.3390/toxins13090590 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/09/210907110647.htm

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