2006 NSERC Steacie Fellow John Klironomos

Getting the dirt on species invasions

As varied and dynamic as we think life on earth might be, there is even more happening underground. A single teaspoon of soil may be home to a million different species, many of them still unknown to us.

This dynamic environment was largely unknown to Dr. John Klironomos, too, as he grew up with little awareness of nature on the highly urbanized island of Montreal. But his imagination was captured during an undergraduate field ecology course at Concordia University, when a look through the microscope revealed the activity of this invisible world beneath our feet.

“You think this is just dirt,” he says. “Right there I realized that there is so much around us, but we just couldn’t see it. That had an effect on me and I was hooked.”

Now an associate professor in the University of Guelph’s College of Biological Sciences and holder of the Canada Research Chair in Soil, Dr. Klironomos has settled on specific objects of fascination that seem even more unlikely: moulds and fungi.

“When you look at a bacterium, typically you just see a little sphere or a rod, but fungi are just out of this world,” notes Dr. Klironomos. “The forms that they have, all the little reproductive structures, the diversity of colours – it’s just unbelievable.”

Such organisms also play a vital role in the sustenance of many plants, settling around their root systems to establish mutually beneficial relationships that provide nutrients and protection from pathogens. In this way, even the most humble fungi can be crucial to the well-being of the crops and forests that we regard as valuable resources.

As one of six 2006 NSERC Steacie Fellows, Dr. Klironomos will be studying these underground relationships even more closely, revealing the implications for life on the surface. Among those implications will be an ambitious exploration of how invasive species move into new territory.

“Whenever we study invasive plants, we study them in that novel habitat that they invaded,” he says. “But to really pin down the mechanisms, whatever study you do in this novel habitat, you should also do in the plant’s native habitat. If you’re going to argue, for example, that one of the reasons this particular species has become invasive is because it has escaped its enemies, you need to go back to see if it really has escaped its enemies. Maybe there were fewer enemies back home.”

According to Dr. Klironomos, very few comparisons of this sort have ever been carried out, largely because of the logistical challenges of tracing invasive species to different parts of the world where they originated or where they have gone. He intends to address those challenges directly, establishing an intercontinental research program on invasion biology that would create an unprecedented network among his counterparts in other parts of North America as well as Europe.

“What it means is running experiments at the same time and in exactly the same way in multiple locations across continents,” he says, emphasizing the necessity of conducting this work at the local level, so that any unidentified organisms in the soil might make their presence known.

“We recognized for a long time that interactions with other organisms – pathogens, pests, herbivores – could be important, but we focused on above-ground ones, where they’re easy to look at, and there is less diversity,” he says. “We’re pretty good at finding some soil microorganism and bringing it into the lab, culturing it, and studying it under a microscope. But the challenge is to really understand what’s going on in the field, as you can’t really poke your head in the ground.”