Just as various ecosystems depend on the structures established by termites, the investigation of these insects also demands a reliable foundation. Recently, a new framework for classifying termites has been developed through the collaboration of an impressive 46 researchers from around the globe.
Termites often get a bad name. Many consider them pests, a perception that has only grown stronger with their recent classification as part of the cockroach family.
However, only about 3.5% of termite species are harmful to humans. In fact, termites are vital ecosystem engineers that help sustain the infrastructure of many environments. Similar to earthworms, they enhance nutrient distribution by breaking down plant materials. Additionally, termites play a critical role as bioturbators: like tilling a field, they aerate the soil, bring nutrients to the surface, and allow water to seep into deeper soil layers, all of which are essential for plant growth. Termite mounds are also remarkable constructions, staying cool even in intense heat, which has inspired energy-efficient cooling systems in innovative architecture.
Just as many ecosystems rely on the foundations laid by termites, so too does the scientific study of termites need a sturdy base. Now, a new termite classification system has emerged from the collaborative efforts of 46 researchers worldwide. Their findings, grounded in expert agreement and thorough data studies, have been published in Nature Communications. “We have clarified the confusion surrounding the previous classification with a modular and robust family tree for termites,” states Dr. Simon Hellemans, the lead researcher from the Evolutionary Genomics Unit at the Okinawa Institute of Science and Technology (OIST). “This new ‘dictionary’ provides a reliable foundation to explore termite diversification and their ecological roles, as well as to accommodate future findings.”
Bringing Families Together by Clarifying Differences
Taxonomy, which is the scientific classification of organisms, is a time-honored field critical to all biological sciences: “To observe anything in nature, you need to clearly define your subjects of observation,” Dr. Hellemans observes. Although classification may seem arbitrary — the organism doesn’t care if we refer to it as Heterotermitidae or Rhinotermitidae — it is necessary for researchers to narrow their study scope and communicate their findings effectively. Prior to the advent of modern DNA sequencing, classifications largely depended on morphological traits, assessing organisms by their physical attributes and behaviors and organizing them based on similarities. While distinguishing between chimpanzees and gorillas can be straightforward, visually differentiating between two termite species can be quite challenging.
As time passed, the subjective nature of morphological analysis led to a muddled classification system for termites. Some termite species evolve rapidly, contributing to their quick diversification. Yet, only ten distinct families were recognized, forcing a wide range of morphologically varied species into unclear evolutionary connections.
Three terms are used to clarify the relationships between classified species: monophyly, polyphyly, and paraphyly. A monophyletic group shares a common ancestor, while polyphyletic groups often have similar traits without a common ancestor, and paraphyly includes a common ancestor along with some but not all of its descendants. The issue with termites, which belong to a monophyletic group within the cockroach order, is that their traditional classification has been marred by significant paraphyly and polyphyly due to obscured evolutionary connections.
“Through extensive data analysis and new morphological assessments, we managed to eliminate paraphyly and polyphyly within the termite family tree by separating the larger subfamilies,” Dr. Hellemans explains. “This approach allows us to create a classification that effectively adapts to the discovery of new lineages while preserving historical family and subfamily names, which is crucial for maintaining a stable taxonomy for termites. Since taxonomy also relies on historical records, this aspect is vital.”
Under the new termite evolutionary framework, every family and subfamily is monophyletic, clarifying the evolutionary connections among species and simplifying the integration of newly found or reclassified species. The updated tree highlights the diversity among termites, enhancing precision in research and pest management. For instance, the harmful termite species Coptotermes gestroi was once placed in the Rhinotermitidae family alongside the non-pest species Dolichorhinotermes longilabius based on their physical similarities. However, earlier phylogenetic analysis suggested that these two species might not be closely related, which has now been validated through advanced phylogenetic and morphological assessments, resulting in the reclassification of C. gestroi into the Heterotermitidae family.
Constructing a Collaborative Foundation
Redefining the life classification system is a complex task. It primarily requires consensus — a dictionary is ineffective if its terms are not agreed upon.
The journey to refresh the termite tree of life began with a symposium at OIST in 2022, organized by Professor Tom Bourguignon, head of the Evolutionary Genomics Unit. Here, the unit proposed a plan to revise the tree of life, which utilized both morphological studies and supercomputer data analyses at OIST. Phylogenetic updates often rely on complex data models that a supercomputer can take weeks to compute, and any adjustments necessitate starting the processing from scratch. “Our classification is based on the convergence of 51 models, each requiring about two weeks to compute,” Dr. Hellemans recalls. “This was feasible only because of Deigo, which enabled us to run analyses in parallel.” Deigo, named after Okinawa’s prefectural flower, is the main supercomputing cluster managed by OIST Core Facilities and is accessible to all OIST researchers.
“Phylogenetics cannot exist in isolation,” Dr. Hellemans emphasizes. While the researchers applied computational models of DNA markers to ascertain evolutionary connections between families, these models do not consider the behaviors of termites or their ecological roles. Such knowledge was supplied by experts who have dedicated their careers to understanding specific groups of these living organisms and possess invaluable scientific insights about the species they study. Dr. Hellemans summarizes the collective effort: “Although coordinating such a large collaborative project was challenging, the new termite classification system represents more than just individual contributions. It strengthens our foundation for studying these essential ecosystem engineers.”
