Professor Jessica Ware, an entomologist and evolutionary biologist, often ventures to the remote jungles of South America in search of dragonflies, damselflies, cockroaches and other insects to find new species and map their evolutionary history.
A few years ago, she and RU-N doctoral student Manpreet Kohli traveled north—way north to the Arctic Circle—in search of an elusive dragonfly named Somatochlora sahlbergi. Kohli traveled to the Yukon Territory in Canada, while Ware headed to Norway, Finland and Sweden. (S. sahlbergi has also been traced to Russia, and more recently to Japan.)
Separated by the Arctic Ocean, Kohli and Ware knew that a handful of earlier researchers had described this understudied dragonfly as a single species from looking at its morphology, or physical traits, but the RU-N duo expected to find large genetic variations within the species, given the distance between their fieldwork locales.
Usually we assume molecular data and DNA sequencing will overturn older research assumptions, but not in this case.
Using modern techniques like DNA sequencing, they instead discovered almost identical genetic makeup across continents.
“Usually we assume molecular data and DNA sequencing will overturn older research assumptions, but not in this case, which is interesting,” says Ware. “I would have bet a mortgage payment that wasn’t the case.”
Their findings were recently published in the journal Scientific Reports, which falls under the Nature family of journals.
Kohli was lead author of the paper, since the research was part of her doctoral dissertation. Ware was co-author, along with fellow biologist Göran Sahlén, from Halmstad University in Sweden, and Will Kuhn, a former doctoral student of Ware’s who is now at the University of Tennessee, Knoxville.
Kohli and Ware are not sure how it is that S. sahlbergi maintains genetic continuity over such long distances and over massive bodies of water, given that greater genetic variation usually occurs due to environmental adaptation in such cases, but they have some hypotheses, which they’ll continue to test.
One possibility is that S. sahlbergi is flying between Europe and Eurasia and mating, though this appears to be a stretch, given the distance in question and the species’ relatively narrow wingspan, which requires it to engage in more flapping flight than gliding to stay airborne. Kohli and Ware can test this by doing isotope tests on their wings in both locations to see if they’re migrating as described.
Another is that S. sahlbergi is changing at a slower rate due to their possibly longer life cycles. “Species with shorter life cycles evolve faster, but this species survives where the water is frozen at least eight months of the year,” says Kohli, “and this may extend its life cycle to 4 or 5 years, which is long for dragonflies. It’s possible that has slowed its evolutionary change and genetic diversity.”
Whatever the case, it’s worth noting that not only is Kohli the first to test this species with modern DNA coding, but she and Ware are picking up on a very limited research trail, given that only a handful of people have studied this species with much care over the last 130 years, and Kohli is the first to do any DNA coding on any dragonfly species in the Arctic, according to Ware.
She adds that studying this Arctic dragonfly species can also tell us a lot about the effect of climate change, since the area has such a fragile ecosystem and gives the world an early look at potentially dire consequences.
“As permafrost melts and lakes start slowly disappearing in this region, S. sahlbergi will be affected. So, studying them now gives us a baseline, a look at what’s happening before their habitat disappears,” says Ware. “Manpreet’s work really moves us forward on this, and she and our lab will continue to monitor and study them.”