[Paleopsych] Ramblin' Wrecks: Study Suggests Humans Can Speed Evolution
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Thu Aug 12 18:01:01 UTC 2004
Study Suggests Humans Can Speed Evolution
Date Released: Tuesday, August 03, 2004
Source: Georgia Institute of Technology
It's no secret that life in the 21st century moves at a rapid pace.
Human inventions such as the Internet, mobile phones and fiber optic
cable have increased the speed of communication, making it possible
for someone to be virtually in two places at once. But can humans
speed up the rate of one of nature's most basic and slowest processes,
evolution? A study by J. Todd Streelman, new assistant professor of
biology at the Georgia Institute of Technology suggests that humans
may have sped up the evolutionary clock for one species of fish.
Cichlid fish are well known to biologists for their rapid rate of
evolution. While it takes many animals thousands of years to form new
species, the cichlids of Africa's Lake Malawi are estimated to have
formed 1,000 new species in only 500,000 years, lightning speed in
evolutionary terms. In the 1960s a fish exporter may have unwittingly
set the stage for an evolutionary explosion when he introduced
individuals of the species Cynotilapia afra to Mitande Point on the
lake's Thumbi West Island. As of 1983, the species hadn't budged from
Mitande Point. But when Streelman, then at the University of New
Hampshire, Durham, and colleagues went to the island in 2001, they
found the fish had evolved into two genetically distinct varieties in
less than 20 years. The study appears in the August 13 edition of
"This is a great example of human-induced evolution in action," said
Streelman. "It adds to a growing list of cases, including introduced
salmon, flies and plants, where human disturbance has set the stage
for contemporary evolution on scales we've not witnessed before."
The fish have evolved into two genetically distinct and differently
colored populations, one on the north side of the island, the other on
the south, said Streelman. Cichlid color patterns are important in
mate selection, so these distinct markings may promote the evolution
of new species.
Whether or not that happens and how long it will take is a question to
which Streelman is eager to find the answer. "It could be that we'll
have new species in another 20 years, although this depends on a
number of factors. Either way, we have a wonderful opportunity to
follow the evolutionary trajectory of these populations over time. We
plan to return to the island next July to do further study," he said.
"Thumbi West will be a valuable place to work for years to come."
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