|
Frontiers
Recreating a Species: Evolution Turns Predictable
November 1996
If a daisy were given another chance at evolution,
would it still look like a daisy? Would a rose still smell like a rose?
Scientists have long wondered how much of a role chance plays in evolution,
and the answer, at least for one species of sunflower, is not much.
If the 100,000-year-old species developed all over again, it would
still be the same.
This was a surprising finding since much of evolutionary theory suggests
that chance is a significant player in speciation.
The research, done by NSF-funded Loren Rieseberg, an evolutionary
biologist at Indiana University in Bloomington, and his colleagues,
was published in the journal, Science. Rieseberg focused
on the anomalous sunflower or Helianthus anomalus because it
is a naturally occurring hybrid. It developed from the interbreeding
of two other sunflowers: the common sunflower (Helianthus annuus)
and the petioled sunflower (Helianthus petiolaris).
The researchers assumed they could interbreed the two parent species
and get another flower, but they did not know if they could still get
the anomalous sunflower, or if a totally new species would develop
after a few generations.
In all three trials, the anomalous sunflower reappeared within
four generations. Not only did the flowers look like their counterparts
found in the Great Basin desert, DNA testing showed that they were
almost identical.
"I was pretty astonished," Rieseberg told The
New York Times. "I expected to see some similarities, some
concordance, but I didn't expect to see anything like this. I think
we'll find that much more about evolution is repeatable and predictable."
|
