Biologists Find Evolution Evidence in Kentucky Caves
Date: Oct. 4, 2000
By: Chris Curran
Phone: (513) 556-1806
Archive: Research News
Photos by: Colleen Kelley and Jacob Hand
Click here for video by Chris Curran
At its simplest, it's the story of a beetle and a cricket. The
cricket lays its eggs buried in the soil deep inside a cave. The
beetle digs up the eggs and eats them.
At its most complex,
it's the story of evolution in action. Different species seeking
the best strategies to survive and reproduce.
Molly White, a
graduate student in biological sciences, is continuing the work
of her adviser, Professor Thomas Kane. He and other UC graduate
students have spent years studying how animals have adapted to
live inside caves.
Previous work has shown that a different
species of cave crickets and cave beetles behave in a similar
manner. White is trying to demonstrate that another cricket-
beetle pair does the same thing.
Her work takes her to the
caves in southern Kentucky, spread across the Lake Cumberland
region. She relies on the good will of private landowners, the
Kentucky Geological Survey, and other government agencies which
control access to the cave sites.
She also requires help. Safe
caving is a team effort, so she never works
On a recent trip, White returned to Overlook Cave near
Somerset, Kentucky to check on her experimental setups. Using a
series of hoops, she's able to measure how successful the cave
crickets are at producing offspring. Some hoops prevent the
beetles from reaching the cricket eggs. Others have gaps,
allowing the predatory beetles access to the eggs.
in Overlook Cave belong to the genus Hadenoecus. What's
interesting to White, Kane, and other evolutionary biologists is
the fact that two different species of cave beetles dig up and
prey on their eggs Darlingtonea kentuckensis and Neaphaenops
tellkampfi. It's the same behavior in two completely separate
"These beetles are the only ones that do this,"
explained White. "But there is absolutely no gene flow between
the species. It's a physical impossibility."
That means that
each species apparently evolved the same behaviors, even though
they are separated physically in different caves and living in
different cave environments. Biologists have studied three
different layers of Mississippian rock formations. The beetles
appear to be doing the same things in all three study
"It's called convergent evolution," explained White.
"The species end up doing the same thing, even though they
started at completely different places."
Convergent and parallel evolution are often cited as support
for the role of natural selection leading to adaptation," added
White's adviser Professor Thomas Kane. "Thus the beetle/cricket
predator-prey interactions support Darwin's view of the
significance of natural selection in evolution."
White says "understanding an ecosystem's past and present can be
helpful in protecting the ecosystem's future."
So, her overall
goal is not just to understand how the cave crickets protect
their eggs. She'd really like to know how humans can protect the
fragile and beautiful environments in which they live.