Drywood termites were the center of a recently published study that involved three decades of sample collection and collaborators from across the world. By sequencing the mitochondrial genomes, the researchers discerned that this family has made at least 40 oceanic voyages in the last 50 million years. Credit: Aleš Buček
If drywood termites caused damage to your outdoor furniture or firewood supply, don’t blame them—blame the ocean they rode in on. That’s according to a new study from researchers at Okinawa Institute of Science and Technology Graduate University (OIST) that mapped out the natural history of drywood termites through unprecedented DNA sequencing of the diverse species.
Kalotermitidae, or drywood termites, are the second largest termite family found across tropical and subtropical ecosystems. They typically live in small colonies confined to single wood items and—before this study—were thought to be primitive. Almost all previous research focused on a different genus within the family that contains common pest species, offering very little data about Kalotermitidae.
Aleš Buček, OIST postdoctoral researcher and lead author, and his team collected hundreds of Kalotermitidae samples from around the world over nearly 30 years. From this collection, they isolated and sequenced the DNA of about 120 species, representing about 27% of overall kalotermitid diversity.
By comparing the genetic sequences from the different species, the researchers constructed an extensive family tree of the drywood termites. According to the study results, published in Molecular Biology and Evolution, Kalotermitidae have made more oceanic voyages than any other family of termites. They’ve crossed oceans at least 40 times in the past 50 million years, traveling as far as South America to Africa, which, over millions of years, has resulted in the diversification of new drywood termite species in these places.
In their study, the researchers found evidence to support two oceanic Kalotermitidae dispersal events to the Neotropical realm, which includes present-day South America and Middle America. Meanwhile, the study shows the Oriental realm, including present-day India and Southeast Asia, was colonized by at least four different oceanic dispersal events. Madagascar experienced the most dispersal events with at least seven independent colonizations.
“Their homes are made of wood so can act as tiny ships,” said Buček. “They’re very good at getting across oceans.”
However, the researchers noted that dispersal events in recent centuries have largely been mediated by humans. For example, four of six colonization events by the genus Cryptotermes in Australia correspond to human introductions. Additionally, while ancient oceanic dispersal events in the Afrotropical realm (which includes Madagascar, the Arabian Pennisula, Southern Africa and more) brought at least six distinct Kalotermitidae genera to the region, the researchers say “human activities from an unknown location” more recently brought C. havilandi to the region.
The study also cast doubt on the common assumption that drywood termites form small colonies exclusively in wood and are primitive in morphology, nesting behavior and social organization. On the contrary, the scientists found that Kalotermitidae can form large colonies across multiple pieces of wood that are connected by underground tunnels.
“This study only goes to highlight how little we know about termites, the diversity of their lifestyles, and the scale of their social lives,” said Tom Bourguignon, principal investigator of OIST’s Evolutionary Genomics Unit and senior author of the study. “As more information is gathered about their behavior and ecology, we’ll be able to use this family tree to find out more about the evolution of sociality in insects and how termites have been so successful.”