Alien invaders are among us. In spring and summer you see them every day. They are everywhere and respect no borders.
Fortunately, York biologist Chris Lortie and his colleague José Hierro at Universidad Nacional de La Pampa in Argentina are on the case. With a team of students from around the world, they are looking for answers a
bout invasive plant species.
In Ontario, a common invasive species is purple loosestrife (Lythrum salicaria), a purple wetland plant native to Europe and Asia which can be easily seen by roadsides, in ditches and in wilderness areas.
Left: Purple loosestrife
Currently, Lortie and Hierro’s team are studying a member of the sunflower family called the yellow starthistle (Centaurea solstitialis), which hails from Eurasia – namely Turkey, Georgia, France and Spain, but is now invading California, Western Canada and Argentina. It is an international pest and requires international cooperation to analyze the problem, understand its biology and environmental impact, and it is hoped, researchers will find a way to control or 
eliminate it.
Right: Yellow starthistle
Lortie and Hierro first met as PhD students under renowned invasive species expert Professor Ray Callaway at the University of Montana. They have maintained a friendship over the years and collaborate on biology projects despite being separated by thousands of kilometres. “Dr. Callaway is probably the world’s most cited ecologist on invasive plant species,” says Lortie. “José and I learned a great deal from him. He’s very inspiring and we are excited to take our experience as foreign students back to the classrooms and labs as professors teaching students – many of them international students.”
Hierro agrees. “York has so many outstanding students and faculty. It is a privilege to work with them – especially with excellent labs and equipment. You are very fortunate and the students who come will benefit. We gain knowledge from students who come here from around the world because they can impart information about their ecology to us that helps our research.
“In turn, we create students with broad skills and a global perspective of invasive species so we can 
provide action plans,” says Hierro. “We are trying to answer the question, ‘When exotic species is not native to an area, why are they so successful?’ The textbook example familiar to people in Ontario is purple loosestrife, but there are many, many more examples all around the world.”
Left: José L. Hierro of Argentina
Lortie and Hierro also enjoy their roles as mentors to a new generation of students from around the world. “Collaboration is key,” says Lortie. “José and I worked together first as students, now as educators. We are separated, but we work together on projects of mutual interest but also of good scientific merit because invasive species disrupt existing ecosystems and that can, potentially, do great harm if it disrupts food chains, agriculture, and so on. These problems are not just local, they are global and require global efforts to understand them and combat them.”
Lortie and Hierro currently have over 400 plants growing in York’s greenhouses and have exchange students from as far away as France, Mexico and South Africa 
taking part in research experiments.
Left: Chris Lortie
“I love being at York because there are so many opportunities for me to be myself and strengthen my character. I feel at home here and that has been really important in asserting myself as a young adult,” says Kate Baker Del Aguila, an international student from Mexico, whose family is currently living in Lebanon. She is a fourth-year biology major focusing on conservation biology and ecology. “As an assistant researcher this experience has been invaluable to my future endeavours as an ecologist. Studying away from home is a privilege, so I try to make the most of the experience. By contributing as a student, a research assistant and a volunteer, I feel I have done the most I can to not just be seen as an international student but rather as part of the York community.”
Right: Jabir Alidina and Kate Baker Del Aguila at work. Photo by José L. Hierro.
“It’s wonderful to have the opportunities to work and study away from home with students from around the world at York. It has a lively atmosphere,” says Hierro.
“I see ourselves in these students,” adds Lortie. “They want to learn and want to take that knowledge back home to help their own communities. It’s great.”
For students interested in exploring exchange or internship opportunities or for faculty interested in York's linkages, please visit the York International Web site, or drop by the office at 200 York Lanes.
Submitted by Edward Fenner, York International