These lizards are leaping for science.
Well, not so much leaping, as falling.
But their tumbles are helping
scientists answer a question.
Could hurricanes drive natural selection?
Hurricanes are destructive -
perhaps too destructive to
influence evolution, with species
survival being more random
than influenced by specific traits.
And while some scientists
suspect that hurricanes
could drive natural selection,
this has never been documented.
That is, until a group
of researchers happened to be
measuring Anole lizards
in the Caribbean.
They surveyed lizards
on two small islands
in Turks and Caicos,
just days before Hurricanes
Irma and Maria struck.
Winds reached speeds of
more than 200 kilometres per hour,
felling trees and flattening vegetation.
But after the devastation,
the scientists had a rare opportunity
to see how the hurricanes affected
the lizard populations.
They went back and
measured the lizards
left on the islands.
On average, those that survived
had larger toepads
and shorter femurs -
the males also
had smaller bodies.
Researchers suspect that
these small differences
might help the animals cope
with high winds.
But how?
Well that brings us back
to lizards falling into nets.
This simple test,
done with a leaf blower,
demonstrates how they
respond to high wind.
To stay on the branch,
the lizards tuck their forelegs
under their body
and out of the wind.
But their hind legs stick out,
catching the wind until
they ultimately lose their grip.
The scientists say that
shorter femurs and smaller bodies
could help them hang on.
Additionally, the lizard’s toepads
are covered in tiny ridges.
Larger pads means more ridges
and so better grip.
Right now, this is mostly
speculation, but it could explain
the differences the researchers
measured after the hurricanes.
And that raises the possiblity
that hurricanes could act
as a selection pressure –
favouring lizards with
wind resistant traits.
And if the traits stay
in the population,
that could drive evolution.
Picking apart processes
like this will help conservationists
predict how ecosystems adapt
to extreme weather events –
which we’ll see more of
as the climate warms.
But for now, let’s appreciate
these little Anoles for their
contribution to evolutionary science.
