Loren Rieseberg has been fascinated by sunflowers for more than two decades - photo by Martin Dee

UBC Reports | Vol. 52 | No. 7 | Jul. 6, 2006

Scientist Puts Sunflower on Evolutionary Map

By Brian Lin

A rose may be just a rose, but sunflowers hold the secret to species evolution, according to Prof. Loren Rieseberg, the Dept. of Botany’s latest recruit.

Rieseberg, who joins UBC this year from the University of Indiana, is one of the world’s leading evolutionary biologists. By studying wild sunflowers that colonize extreme habitats — such as deserts and salt marshes — he and his team seek to unravel the mystery of how species arise.

“We use a combination of genomic and ecological approaches to understand both the emergence of new species of sunflowers and how they became domesticated,” says Rieseberg, who received the US $500,000 McArthur Foundation “Genius” Fellowship in 2003 and is a Canada Research Chair in Natural Sciences and Engineering.

“The traditional belief is that hybridization — or mating of plants from different species — is an evolutionary dead end because hybrids often are sterile or inviable,” explains Rieseberg, whose research has been funded by the U.S. National Science Foundation, the National Institutes of Health, and the Department of Agriculture.

“But my colleagues and I have found that for sunflowers, hybridization with related species actually leads to an explosion of variation, allowing them to adapt to previously uninhabitable environments,” says Rieseberg.

Rieseberg’s lab has reproduced such naturally occurring hybrids in the greenhouse and successfully transplanted the resulting hybrid lineages to salt marshes in Mexico and sand dunes in Utah.

“This shows that natural selection is the driving force of speciation, and that evolution is recurring and repeatable,” says Rieseberg.

Born in Alberta and raised in the Okanagan Valley, Rieseberg has fond memories of spending his summers in Vancouver and says he’s excited to return to British Columbia after spending most of his academic career in the United States.

“There is a very strong evolutionary biology research group at UBC, and we’re head-to-head with the world’s top universities, particularly in speciation research,” he says. “The human resources here are simply amazing.”

Rieseberg is also one of an increasing number of researchers in the world paying attention to the evolution of weeds, a project that could help industry better control invasive plants and weeds.

“We’ve been developing gene catalogues for weeds in the sunflower family — including various thistles, knapweeds, and dandelions — to identify the genetic changes that allow them to become invasive.”

“Loren is widely acknowledged as one of the world’s leading evolutionary biologists, and arguably the best plant evolutionary biologist in the world currently,” says Carl Douglas, head of Dept. of Botany. “There are many practical spin-offs for his work, regarding the evolution of traits such as salt tolerance and invasiveness.”

In a 2003 Science magazine profile, Vanderbilt University evolutionary biologist John Burke credits Rieseberg for putting sunflowers on the evolutionary map, alongside the fruit fly and finch.

“It would be fair to say the sunflower has developed into the system for the speciation of plants, largely — or solely — because of Loren,” said Burke.