When the Moon Sets the Rhythm

The GEO magazine features Tobias Kaiser’s lunar clock research at the Max Planck Institute for Evolutionary Biology

To the Point

• GEO spotlights Tobias Kaiser’s lunar clock research in its April issue.

• The team in Plön works with a globally unique model system: the marine midge Clunio marinus.
• Their research opens up new perspectives on how lunar rhythms function and how they contribute to evolutionary adaptation.

Not all biological clocks follow the cycle of day and night. Some organisms also respond to the moon. In its April issue, GEO magazine explores this fascinating field of research and highlights the work of Tobias Kaiser at the Max Planck Institute for Evolutionary Biology in Plön.

Tobias Kaiser’s research holds a special place in this field: his group is the only one in the world working on the marine midge Clunio marinus. Their research focuses on how the internal lunar clock works, how it interacts with environmental cues such as light and tides, and how it has adapted over the course of evolution to the conditions found at different locations.

In the laboratory, numerous populations of Clunio marinus are maintained, including strains from France, Sweden, Germany and Spain. In total, the team works with eleven strains which, despite being kept under identical conditions, show clear differences in their lunar rhythms. Some strains mate only at full moon, others only at new moon; some respond not to moonlight but to simulated tides, while others appear to have no rhythm at all. These differences are precisely what make the collection so valuable. On the one hand, they reveal the diversity of evolutionary adaptations to habitat that can exist within a single species. On the other, these differences can be analysed using genetic and molecular methods, providing insights into the mechanisms of the lunar clock.

These animals offer a rare window into a field of research that remains largely unexplored. As GEO notes, much about the lunar clock is still not yet understood. Tobias Kaiser has been working on Clunio marinus for around 20 years. During this time, his group has shown that differences in the lunar clock are genetically anchored and has also identified genes likely to play a role. Their work has further shown that the lunar clock does not operate independently, but interacts with the circadian clock.

It is precisely this combination of fundamental research, biological precision and a globally unique model system that makes the work in Plön so remarkable. The research shows how finely tuned living organisms are to the rhythms of nature – and how much there still is to learn about these processes.

The Article was published in the GEO Magazine Issue 04/2026 in the printed version, and only in german.