Biology pair investigates the mysteries of tree sex

O'Leary and Poulis

For the past five years, undergraduate "squirrels" have been foraging on the UVic campus in an effort to unlock the mysteries of tree sex.

Under the direction of graduate students Stephen O'Leary and Brett Poulis, the human squirrels collected conifer cones for a never-done-before experiment. O'Leary and Poulis graduate this month with a PhD in biology.

"When a real squirrel eats a Douglas fir cone, it picks apart each piece to get to the seeds inside," explains O'Leary. "That's what our human squirrels were mimicking."

Conifer fertilization takes place when pollen is blown on the wind and lands on cones. Within these cones are small liquid droplets that capture the pollen and begin the process of reproduction. Until now, the properties of this liquid were a mystery.

"We wanted to find out what is in these droplets, what proteins are present," says O'Leary. "Until now there was no technology to deal with such a small volume of liquid."

Fertilization—or tree sex—takes place for only a week at a time per year. The undergraduate students employed by O'Leary and Poulis collected cones for 10 hours a day, going from tree to tree. The cones were then brought back to the lab and taken apart with tweezers. Next, the students extracted the droplets from the cones with a micropipette.

"Finally, we put all the drops into a container and froze it," says Poulis. "At the end of all that, we have about one to one-and-a-half a millilitre of liquid, depending on the tree."

The pair discovered that components within the liquid protected the reproductive events from bacterial and fungal infection. The liquid may also nourish pollen germination and development. "We were pleased because we knew we were pushing conifer science forward, especially in B.C. where softwood lumber plays such an important role," says Poulis.

Poulis, who earned his undergraduate degree in chemistry and biochemistry at UVic, has seen both sides of tree lore—as a researcher and in summer jobs heli-logging and fighting forest fires. "I like the outdoors, especially since I was born and raised in B.C.," he says.

O'Leary's appreciation for trees came later in life. Originally from Nova Scotia, he graduated from St. Francis Xavier University with a biology degree. "I spent a summer in the Gulf Islands working on an algae project and decided I wanted to move back to the Pacific Northwest," he says. "I've been here for six years now."

In November, O'Leary starts work in Ottawa as a visiting fellow with Agriculture and Agri-food Canada. Poulis will continue to plumb the mysteries of conifers as a research associate with UVic biologist Dr. Patrick von Aderkas.