Another Example of Natural Selection

Steven M. Smith (
Mon, 05 Apr 1999 12:56:39 -0400

Many threads on this listserv have recently asked for or discussed
examples of natural selection in action. (e.g. Peppered Moth threads,
Where is Evolution? thread). The following excerpts from a copyrighted
article in the Washington Post describe a situation where we have a
'natural experiment' in evolution taking place: an recently created
extreme environment and organisms adapting to that environment over
multiple generations. Note: The 'emphasis' of this article was not to
'prove' natural selection but to report on the possibility that these
'newly evolved' organisms may lead to cancer cures or other medical
breakthroughs. Nevertheless, there are several implications that
pertain to discussions here. Optimistically speaking, the results of
this 'natural experiment' may become another textbook example of natural
selection leading to speciation ... or evolution.

The complete text of the article may be found at:

Could a Toxic Lake Yield Life-Saving Microbes?

By Mark Matthews
Special to The Washington Post
Monday, March 8, 1999; Page A09

BUTTE, Mont.÷One fall night a few years ago, more than 200 snow geese
landed on the water inside the Berkeley Pit, an abandoned copper mine on
the edge of this hillside town. The next morning all the birds were dead,
floating feet up on the lake's blue surface.

Researchers once thought all living things that landed in the pit surely
died, but they've had some surprises lately. Some single-celled life
forms, unseen by the human eye, that blow into the pit or drift in with
surface water are surviving. Some have even evolved to the point where
they can't exist outside the toxic stew. Scientists have identified some
of these life forms, but others remain a mystery.

The 1.5-mile-wide, 1,800-foot-deep pit, part of the nation's largest
Superfund site, has been filling for the last 17 years with a poisonous
broth laced with heavy metals and arsenic--a legacy of Butte's copper
mining days. When mining officials abandoned the pit about 17 years ago
and stopped the pumps that kept it dry, they opened the spigots to about
3 million gallons of water per day. Today, the lake is about 850 feet
deep and contains more than 3 billion cubic feet of water. It is supplied
by an aquifer that contains approximately 57 billion gallons of
metal-laden water.

The contamination in the Berkeley Pit is typical of many existing and
former hard rock mining sites where exposed sulfide minerals have reacted
with water and air to produce highly acidic waters, said Mary Ann
Harrington-Baker of MSE Technology Applications Inc., which
co-administers the Mine Waste Technology Program with the University of
Montana College of Technology.

For years, engineers who have monitored the pit assumed the water, which
is about 10,000 times more acidic than normal--like battery acid--could
not support life. Then a few years ago, a curious analytic chemist,
William Chatham, noticed a small vegetative clump floating on the water's
surface. It turned out to be made up of "protists," one-celled
microorganisms. Since then, biologists and natural products chemists have
isolated 42 different kinds of organisms living in the acid solution,
including algae, bacteria, protozoans and fungi.

"There's every organism you could imagine," said Grant Mitman, a Montana
Tech biologist who has identified many of the creatures.

The survivor microbes are far from prolific, but can be found at various
depths. And their numbers sometimes fluctuate with the seasons.
Scientists are studying the microbes and their biological products to see
if they can't be used in some way, perhaps even to clean up the pit

"We're looking at the bright side of the Berkeley Pit," said Andrea
Stierle, a natural products research scientist who, with her husband Don,
is looking for novel sources of anticancer, antifungal and antibacterial

[... Snipped 2 paragraphs ...]

Some pit organisms develop after spores blow into the water. While these
seem to barely survive in the extreme environment, others thrive. "There
is a percentage of the organisms that luxuriate in pit broth," Andrea
Stierle said. Some organisms may even have evolved in the pit since the
waters began accumulating. "Fourteen years equals thousands of
generations for these organisms," Stierle said. "We may be seeing the
results of natural selection."

[... Snipped remainder of article ...]

© Copyright 1999 The Washington Post Company


Steve Smith
[The opinions expressed here are my own
and are not to be attributed to my employer.]

Steven M. Smith Office: (303)236-1192
U.S. Geological Survey Fax: (303)236-3200
Box 25046, M.S. 973, DFC
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