Many families of land animals live separated by hundreds of miles of oceans wide and wide. The explanations for how they got so far apart are as varied as the animals themselves.
Lately, many animals have been hitchhiking around the world with humans, on our vehicles, food, and on our bodies.
Before that, hundreds of millions of years ago, the continents were connected and animals could just walk across the land.
But between then and now, there seems to have been a lot of floating and hoping for the best.
A new study has found that the drywood termite family (Kalotermitidae) is an expert at it, having successfully crossed the ocean at least 40 times in the past 50 million years.
Termites are flying creatures, and while you can imagine they could make the journey by plane, they’re actually pretty bad at flying long distances, so they’re better suited to crossing vast bodies of water using another mode of transport.
“They are very good at crossing oceans,” says the study’s lead author Aleš Buček, an evolutionary geneticist from the Okinawa Institute of Science and Technology Graduate University (OIST) in Japan.
“Their houses are made of wood, so they can act like tiny ships.”
Researchers highlight the Krakatoa Islands to illustrate this. A devastating volcanic eruption in 1883 left the entire area barren, but several species of drywood termites had recolonized the area after just 100 years.
“The dispersal ability of Kalotermitidae stems from their lifestyle, as they typically nest and feed on individual pieces of wood that can swim across oceans as rafts,” the team writes in their article.
“Most extant species of Kalotermitidae are unable to forage outside of their nesting piece of wood. Instead they form small colonies in wooden objects like dead branches on living trees.”
To find out, the team didn’t put drywood termites on small boats and set them out to sea (although that would have been adorable). Instead, they studied the genetics of the drywood termite family Kalotermitidae and charted how their mitochondrial DNA traveled around the world.
Analyzing hundreds of drywood termite samples from around the world collected over the past 30 years, the researchers focused on around 120 species of termites, representing 27 percent of the Kalotermitidae diversity and almost all of the different genera, giving the Team a lot of information to work with.
A world map showing where the termites were collected. (Buček et al., MBE, 2022)
“Drywood termites, or Kalotermitidae, are often considered primitive because they split off from other termites fairly early, around 100 million years ago, and form what appear to be smaller colonies,” says Buček. “But actually very little is known about this family.”
By genetically tracing their family tree, the researchers found that the earliest common ancestor lived 84 million years ago. This means that some of the early splits in the family tree may have occurred over land before the supercontinent Gondwana completely broke apart.
Most of the 40 or so fissions, however, occurred less than 50 million years ago, suggesting these little landhoppers traveled across the sea. More recently, human travel has likely helped termites as well.
Importantly, the analysis also suggests that we’ve been a little too harsh on these little guys and their “primitive lifestyle.” The Kalotermitidae typically nest in small groups on a single piece of wood, which many researchers have interpreted as the “primitive” way of life of termites, before larger and more complex colony organizations later evolved.
However, according to the researchers, some of the oldest lines in the genetic family have been feeding on multiple pieces of wood, suggesting that the single piece of wood strategy may be a relatively recent adaptation, possibly driven by competition.
“This study only underscores how little we know about termites, the diversity of their lifestyles and the extent of their social life,” says OIST ecologist Tom Bourguignon.
“As more information about their behavior and ecology is gathered, we can use this family tree to learn more about the evolution of insect sociality and why termites have been so successful.”
The research was published in Molecular Biology and Evolution.
