Scientists say they have caught "evolution in the act" in a series of experiments that open a new window into understanding how new species gradually morph into plants and animals that are distinctly different from their parents.
The experiments, conducted at the University of Florida in Gainesville, surprised the scientists by demonstrating that the development of a new species doesn't occur instantly, but instead is the product of succeeding generations that are able to alter their genetic blueprint as they gradually mature into a stable plant or animal.
The star of the show is a humble member of the daisy family, Tragopogon miscellus, better known as "goatsbeard," which began its long journey toward stability about 80 years -- and 40 generations -- ago.
"We can see for the first time what happens when a new species is formed," biologist Doug Soltis of the University of Florida said in a telephone interview. "We can see the process unfold, and it's still ongoing even as we speak. They (the plants) haven't figured all this out yet."
The research, published in the journal Current Biology, offers some startling insights. The new species first appeared in the Pacific Northwest sometime after 1920 when its parents produced a hybridized offspring with double the number of chromosomes. But unlike its parents, the genes were not rigidly programmed to perform certain functions. Instead, for many generations the genes acted sort of like free agents.
"Different genes are expressed at different times and in different places," Soltis said. So the new species had much greater diversity than would have been expected, creating a genetic blueprint as it went along, from one generation to the next, turning some genes on, and others off, and eliminating some entirely.
That, of course, gave goatsbeard an enormous advantage in adapting to new environmental challenges or opportunities.
"This is evolution at work," Soltis said. "You can see the fine tuning begin to take place."
Soltis began this research back in the 1980s when he and his wife, Pam, were living in Pullman, Washington.
Pam, who is now curator of evolutionary genetics at the Florida Museum of Natural History and a co-author of the study, and her biologist husband were intrigued by a daisy-like plant growing in their own backyard. It turned out that the flower was a hybridized product of two species introduced from Europe about 80 years ago.
Those same two species had hybridized in Europe earlier, but the resulting plant failed. In America, however, the new species was roundly successful, quickly surpassing its own parents and spreading rapidly.
The offspring had doubled its number of chromosomes, a normal process in species formation, but something else clearly was at work. Years later, the couple began experimenting with the plant in a lab they share on the Gainesville campus.
It was an extraordinary opportunity because the flower had evolved recently, "before our very eyes," as Soltis put it, and it had already passed through about 40 generations in 80 years, leaving a genetic history.
They were able to duplicate in the lab what they had already observed in nature, but in controlled conditions.
"The brand new individual that we made in our greenhouse seemed like it had a reset button," Soltis said.
It could reassign its genes, defying the widely-held belief that a genetic code is a fairly rigid blueprint. Instead, the researchers found "variations from plant to plant and which genes they are expressing and which ones they are eliminating. They are still trying to sort this out themselves."
"What we found was a surprise," said Richard Buggs of Queen Mary University in London, who worked on the study as a postdoctoral researcher at the Florida museum and lead author of the report. The "reset button ... could allow subsequent generations to experiment by switching off different genes."
Until now, it was not known that the evolutionary process took place over many generations.
"We didn't know how quickly it happened," Soltis said. "Is this something that occurs almost instantly? It's not. You can see that after 40 or 50 generations. They are still making decisions. We didn't know that. We still don't know how long it takes for this to sort out and settle down and stabilize."
Evolution is frequently described as a "typo" in the genetic blueprint, but this research suggests it is much more complicated, and fluid, and diverse than the instantaneousness of a typo.
It's likely that this is the evolutionary path taken by all life forms, from plants to vertebrates, and it occurred in our own lineage many years ago. A new species slowly makes its way through life, allowing succeeding generations to reprogram genes to meet new challenges, thus emerging as a stable plant or animal after finding the most successful combination.
This new work is an intriguing window into evolution, but like all good science, it also raises a number of questions. What's the triggering mechanism? What causes a daisy to make a "decision" about how to deploy, or eliminate, a specific gene?
"That's a great question," Soltis said. "Right now we are just beginning to understand that they do that. What are they responding to when it happens? I don't really know that we have an answer to that."
So for now, they will keep looking through that new window. And all because of a daisy that attracted the attention of a couple of young scientists nearly three decades ago.