Swan Research Combines Conservation Biology, Climate Change, and Genetics
The swan research program at Environmental Studies on the Piedmont, near Warrenton, Virginia, manages one of the largest research swan collections on the East Coast. Here, Mason researchers Patrick Gillevet and Thomas Wood have collaborated for 10 years with William Sladen, founding director of the program and professor emeritus in the Bloomberg School of Public Health at Johns Hopkins University, in research on North America’s native swans—the trumpeter and the tundra.
Gillevet, director of the Microbiome Analysis Center and a professor in the Department of Environmental Science and Policy (ESP), has brought his research focus on environmental molecular biology to swan genetics. Because the collection is home to the world’s only known hybrids of the trumpeter and tundra swans, he and his team have been able to study all three variations.
We found that the hybrid offspring were fertile,” Gillevet says, “which led us to work on the genetics to see if primers existed to distinguish the hybrid in the wild.”
Wood, whose research focus is conservation biology, is a professor in Mason’s New Century College and director of Environmental Studies on the Piedmont. There, he is investigating the behavioral and physiological evolution of the trumpeter and the tundra swans.
“What we’re trying to find is any genetic information that correlates to the divergence of the swan species, specifically their vocalization, behavior, and morphology,” says Wood.
In summer, both species nest and breed in Alaska—the trumpeter swan in boreal forests and the tundra swan on the Arctic tundra. Both species traditionally migrated to the East and West Coasts for winter. However, the migratory trumpeter population on the East Coast was long ago hunted to extinction for skin and feathers; the population that migrates to the West Coast survived.
Gillevet’s population genetics study seeks to discover whether the two species are reproducing in the wild. He and his students are using next-generation genomic sequencing to search for markers in samples from swans in the Environmental Studies collection. Their results show that the two species are more closely related than previously hypothesized.
“We think there are three possible causes, or a combination thereof, for the closer genetic relationship,” explains Gillevet. The first possibility is a natural evolutionary process. The second is a population disruption caused by the near-extinction of the trumpeter swans and their subsequent reintroduction. The third is the two species’ overlapping breeding ranges as the boreal forest expands into the tundra because of climate change.
Mason doctoral student Lauren Wilson is working with Gillevet. “This research provides a great opportunity to investigate the relatedness of two living things, as well as possibly addressing how climate change has indirectly altered the evolutionary trajectory of species through vegetative disturbance,” Wilson says. “When habitat changes, the animal community responds, sometimes in fascinating but serious ways.”
Wood is studying the calls of both species to compare their vocalization characteristics and has confirmed that the trachea of each species is different.
The trumpeter has a longer, larger trachea than the tundra, and this difference is what produces the trumpeter’s namesake call. “Because the swans breed in different locations, they may have developed different vocal patterns for communicating through the boreal forest versus out on the tundra,” Wood notes.
The big picture—the evolution of the trumpeter and tundra swans—is where Gillevet’s and Wood’s research projects converge. Their studies explore population genetics, climate change, conservation biology, and interspecies differences, and how these factors affect the swans’ evolution. Their findings on the effects of climate change, migratory pattern adaptation, and species reintroduction have significant implications for other Arctic species and help advance the dialogue on conservation biology.
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