By Leah Coppella

What is it about a pine tree that could make it a good defender against the devastating mountain pine beetle?

Prof. Catherine Cullingham would argue that it’s in the genes.

Cullingham was at the University of Alberta, researching pine-tree genetics, before joining Carleton University’s Department of Biology this summer.

She fell in love with molecular biology during her undergrad at Guelph University, where she studied molecular biology and genetics, and went on to complete a PhD in watershed ecosystems at Trent University.

Dr. Catherine Cullingham smiles while hugging her small daughter beside a forested-lake.

Catherine Cullingham

During her doctoral work, Cullingham researched conservation genetics and landscape genetics, a field that looks into how we can understand an animal’s movement using its genes.

Her work also intersected with health. She researched where racoons are likely to move to help predict where rabies would eventually spread.

“There’s always some pathogenic disease that I’m looking at,” she says, “trying to use the genetics of the host to better manage the disease.”

When Cullingham first started in this field, it was entirely new. The term “landscape genetics” wasn’t coined until 2002.

The field has grown since then. So much so that her Genomics of Plants, Pathogens and Pests (GP3) lab at Carleton is using methods from molecular biology, landscape ecology, population genetics, genomics and geographic information systems to study a huge range of issues in wildlife management, such as the pine beetle — which takes the research outside the lab and gives it significant real-world applications.

The Devastating Pine Beetle Outbreak

This year at Carleton, Cullingham is hoping to build on her research about the mountain pine beetle — a wood-boring insect that has been attacking a range of pine tree species in Alberta and British Columbia in an outbreak that began more than 20 years ago.

“Once it moved into Alberta around 2006, it was attacking pine trees within the lodgepole and jack pine hybrid zone,” she says. “It was difficult to identify whether pure jack pines were being attacked, because hybrids can be difficult to distinguish from the pure species. My research confirmed what forest managers suspected — that jack pines are susceptible to the mountain pine beetle.”

The beetle is now slowly making its way toward central Canada, and Cullingham says that in Ontario additional plant species are likely susceptible to it. Which is where her current research comes into play.

“The idea is to try to identify what genes are involved in defense and whether there are certain variations in those genes that make some species better defenders,” she says. “It might not even be in the genes. It might be how the genes are turned on and off, how they’re regulated.”

One of the challenges to her research is the sheer size of the pine tree genome, which is 10 times larger than the human genome. Moreover, because her work is focused on natural populations, her samples always come from the wild, which can be challenging to obtain.

“They’re not an easy species to study in a lab,” she says about pine trees. “There are other people in the department who work on small plants, model systems, things that we know a lot about. Pine trees are something that we still need to learn a lot about.”

An upward view of a dense pine forest with a blue sky above.

Climate Change Could Contribute to More Severe Outbreaks

In January, Cullingham will start teaching a class on population genetics, and she’s looking for students to join her team in the GP3 lab in December.

“The work I do is critical, especially right now,” she says. “Climate change is happening, and with climate change, it changes the dynamics of forest-pest interactions. You’re going to get potentially more severe insect outbreaks because the trees are stressed from things such as drought and extreme heat.”

The mountain pine beetle outbreak has major economic implications too, Cullingham adds. The trees she looks at are used for lumber, pulp and paper.

“They’re also important beyond the ecosystem services — like carbon sequestration — that they provide,” she says. “They’re important habitats for a number of keystone species, endangered species and species at risk.”

Studying tree genetics also gives you insight into the bigger pictures, continues Cullingham. You see that trees provide human enjoyment through public parks and their natural beauty, in addition to serving as homes for mammals, insects and birds.

“I’m really excited to be here and starting up a lab and mentoring students,” she says. “I really enjoy this aspect of being an academic.”

Thursday, July 18, 2019 in ,
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