A joint team of researchers from Kiel, London, Oldenburg, and Davis, California, successfully used a pioneering genetic clock to determine the age of a giant clone of a marine plant. They were first dated to the migration period of a seagrass clone in the Baltic Sea, about 1,400 years ago. This innovative clock has the potential to be used in a wide variety of species, including corals, algae, and terrestrial plants such as reeds and raspberries. Their findings were published in a journal Nature Ecology and Evolution.

Professor of marine ecology at the Helmholtz Research Center GEOMAR in Kiel, study leader Dr. “Vegetative reproduction as an alternative method of reproduction is widespread in the animal, fungal and plant kingdoms,” explains Thorsten Reusch. Called “clonal strains,” these species produce genetically similar offspring through branching or budding, often reaching a size of the size of a football field or larger. However, these puppies are not genetically identical.

Previous work by a group led by GEOMAR researchers had already shown that somatic mutations accumulate in vegetative lineages, a process similar to cancer. Now Professor Reusch, Dr. A team led by Benjamin Werner (Queen Mary University of London, QMUL) and Professor Iliana Baums (Helmholtz Institute for Functional Marine Biodiversity at the University of Oldenburg, HIFMB) used this process of mutation accumulation to develop a new species. Molecular clock that can determine the age of any clone with high accuracy.

Application of the genetic clock

Researchers led by Professor Reusch from the University of Kiel applied this new clock to a worldwide dataset of the vast seagrass Zostera marina, which extends from the Pacific to the Atlantic and the Mediterranean. The team found clones several hundred years old, comparable to the ages of large oak trees, especially in Northern Europe.

The oldest clone identified was 1402 years old and came from the Baltic Sea. This clone reached a very advanced age despite the harsh and changing environment. This makes the waterspout clone older than the Greenland shark or ocean quahog, which live only a few hundred years.

These new estimates of the age and lifespan of clonal species fill an important knowledge gap. Many important habitat-forming species, such as corals and seagrasses, especially in marine habitats, can reproduce vegetatively and their clones can reach very large sizes. The continued production of small, genetically identical but physically separated shoots or fragments from the parent clone means that age and size are irrelevant in these species. The new study provides a tool to date these clones with high precision. “Such data are a prerequisite for solving one of the long-standing puzzles in conservation genetics, namely why such large clones can persist despite a changing and dynamic environment,” says Torsten Reusch.

Once a high-quality algal genome is obtained, work can begin. Another important factor in the study was that colleagues at the University of California, Davis (UC Davis) kept a seagrass clone in culture tanks for 17 years, serving as a calibration point. He is a lecturer in mathematics and cancer evolution at QMUL, focusing on the somatic evolution of clonally developing tumors. “This paper shows how interdisciplinary interaction between evolutionary cancer biologists and marine ecologists can lead to new insights,” says Benjamin Werner. Professor Dr., molecular ecologist at HIFMB “We can now apply these tools to endangered corals to develop more effective conservation measures, which we urgently need as unprecedented heat waves threaten coral reefs,” adds Iliana Baums.

“We expect other seagrass species of the genus Posidonia, exceeding ten kilometers in length, and their clones to show even greater ages, thus becoming the oldest organisms on Earth,” says Torsten Reusch. These will be the next research objects.