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Past Winner
2005 E.W.R. Steacie Memorial Fellowship

Michael Doebeli

Biology

The University of British Columbia


Michael Doebeli
Michael Doebeli

Optimal adaptation to the environment is only part of the evolutionary story, says evolutionary biologist Dr. Michael Doebeli, one of six winners of the 2005 NSERC E.W.R. Steacie Memorial Fellowship. Sometimes it's being different that wins the day.

Big Idea: "The Darwinian idea of survival of the fittest is often interpreted to imply that only one type, the best, will prevail. However, there's not always natural selection for a single best type, and by implication for everybody to be the same as everybody else. Instead, under certain conditions, there is selection for being different from everybody else," says Dr. Doebeli, a professor at the University of British Columbia.

The Question: What drives the origin of new species and diversity of life we see on Earth? The dominant explanation is geographic isolation. Populations become physically isolated from one another by natural events, such as continental drift. Then over millions of years these separate groups evolve into different species through adaptation to different environments.

But Dr. Doebeli says this allopatric ("different place") theory is only one possible explanation for the origin of new species. His research shows that two species can emerge from a single ancestor without anyone leaving home. This process, called sympatric ("same place") speciation, hinges on the adaptive significance of being different. For example, if everybody eats the same type of food, it might be advantageous to eat a different type of food, even if that type is less nutritious.

"When thinking about physically separate places like islands, it's easy to imagine that if you let evolution run for a long time then you'll end up with different plants and animals," says Dr. Doebeli. "But for many species it's not so easy to see that differences between them originated due to a physical barrier."

Research at the Edge: To some, Dr. Doebeli is an interloper in the world of evolutionary biology, since his Ph.D. from the University of Basel, Switzerland, is in pure mathematics. But it’s exactly this background that is his theoretical wedge. Dr. Doebeli uses mathematics to model the process of speciation.

In a landmark 1999 paper in Nature, he and colleague Ulf Dieckmann provided a theoretical framework for sympatric speciation. They demonstrated that, at least theoretically, ecological forces such as competition for food among individuals can lead to speciation without physical separation.

"Our models were a mathematical crystallization of what a lot of people were thinking," says Dr. Doebeli. But the models also drew scientific fire for being too general, and therefore not-of-this-world.

"There's a turf war going on between people who think that sympatric speciation is a plausible process and people who adhere to the traditional dogma of allopatric speciation,” says Dr. Doebeli.

So he did what few theoreticians do: he hit the lab and helped develop experiments to test his theory. The results, published in 2004 in Evolution, showed that the theoretical models hold water. Over the course of four months, a graduate student of Dr. Doebeli's grew E. coli bacteria on a mix of glucose and less attractive acetate food. After 1,000 generations, the single ancestral population had diverged into two distinct types: one that stuck to the easier to digest glucose, and another that had adapted to more efficient use of the acetate.

The Next Step: As part of his NSERC Steacie Fellowship research, Dr. Doebeli's lab group will use their E. coli system to further explore the dynamics of speciation.

"With these bacteria you can study the process of diversification on different biological levels, from genes to the whole organism and the environment," says Dr. Doebeli. He'll explore whether, as his theory predicts, the two distinct types of bacteria he produced earlier, if separated and subjected to the same conditions again, will rediversify.

He'll also be extending his research on the related question of the evolution of cooperation. In a recent paper in Science, Dr. Doebeli and colleagues showed theoretically that when producing a common good, such as an enzyme, populations can diversify so that some individuals make large contributions to the common good, while others freeload on this public resource. He'll test this experimentally with microorganisms, such as yeast.