Termites are a type of cockroach that split off from other cockroaches around 150 million years ago and evolved to live socially in colonies. Today, there are many species of termites. Some form large colonies with millions of individuals, which tend to live in connected tunnels in the ground. Others, including most species known as drywood termites, form much smaller colonies of fewer than 5,000 individuals and live primarily in wood.
Researchers from the Evolutionary Genomics Unit at the Okinawa Institute of Science and Technology Graduate University (OIST), alongside a network of collaborators around the world, have mapped the natural history of drywood termites – the second largest family of termites – and revealed a number of ocean voyages that accelerated the evolution of their diversity. The research, published in Molecular biology and evolution, sheds light on the origin of termites and how and when they spread across the world. It also confirms that some species have, in recent centuries, hitchhiked with humans to reach distant islands.
“Drywood termites, or Kalotermitidae, are often considered primitive because they split off from other termites quite early, around 100 million years ago, and because they seem to form smaller colonies” , said Dr. Aleš Buček, postdoctoral researcher at OIST and lead author. of the study. “But we know very little about this family.”
Dr. Buček went on to explain how, prior to this study, there was very little molecular data on the family and little understanding of the relationships between the different known species was based on their appearance. Previous research had focused on a genus within the family that contains common pest species often found in homes.
To gain global knowledge, the researchers collected hundreds of samples of drywood termites from around the world over a period of three decades. From this collection they selected about 120 species, some of which were represented by multiple samples taken from different locations. This represented more than a quarter of the diversity of Kalotermitidae. Most of these samples were taken to OIST where the DNA was isolated and sequenced.
By comparing the genetic sequences of different species, researchers have constructed an extensive family tree of drywood termites.
They found that drywood termites made more ocean voyages than any other termite family. They crossed the oceans at least 40 times in the last 50 million years, traveling as far as South America to Africa, which, on a time scale of millions of years, led to the diversification of new species of drywood termites in newly colonized places.
“They are very good at crossing oceans,” Dr Buček said. “Their houses are made of wood and can therefore serve as small ships.”
The researchers found that most of the genera originated in South America and spread from there. It takes millions of years for a species to divide into several after displacement. Research has also confirmed that, more recently, dispersals have been largely mediated by humans.
Additionally, this study challenged the common assumption that drywood termites have a primitive lifestyle. Among the oldest lines of the family, there are species of termites that do not have a primitive way of life. In fact, they can form large colonies on several pieces of wood connected by underground tunnels.
“This study only highlights how little we know about termites, the diversity of their lifestyles and the breadth of their social lives,” said Professor Tom Bourguignon, principal investigator of the genomics unit. evolutionary of the OIST and lead author of the study. “As more information is gathered about their behavior and ecology, we can use this family tree to learn more about the evolution of insect sociality and the success of termites.”
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Aleš Buček et al, Molecular Phylogeny Reveals the Past Transoceanic Voyages of Drywood Termites (Isoptera, Kalotermitidae), Molecular biology and evolution (2022). DOI: 10.1093/molbev/msac093
Provided by Okinawa Institute of Science and Technology
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