Organisms, including humans, have internal clocks that coordinate important bodily functions with environmental cycles. While most organisms have circadian rhythms synchronized with the day-night cycle, marine animals have circatidal rhythms that align activities with the tidal cycle. Researchers from Chiba University have discovered that freshwater snails living in downstream tidal areas have biological rhythms synchronized with tidal cycles, raising questions about the causes of circatidal rhythms.
Associate Professor Yuma Takahashi and Dr. Takumi Yokomizo from Chiba University studied freshwater snails (Semisulcospira reiniana) from tidal and non tidal areas along the Kiso River in Japan. The snails were divided into two groups, one exposed to a 24-hour light-dark cycle and the other to a simulated 12-hour tidal cycle. The researchers found that snails from tidal areas exposed to the simulated tide showed stronger circatidal rhythms compared to the control group, suggesting that biological rhythms can adapt to dominant environmental cycles.
The study, published in the journal Heredity, revealed genetic and non-genetic changes in biological rhythms in freshwater snails adapting to tidal environments. Snails that had already adapted to tidal cycles in their early life had a greater number of circatidal oscillating genes compared to the non-tidal population. The results suggest that the expression rhythms of genes controlled by the biological clock are sensitive to environmental changes and can be influenced by genetic changes resulting from environmental adaptation.
The researchers found that disruptions to biological rhythms can negatively impact various physiological processes. Understanding how organisms adapt to changing environmental conditions, as seen in the study on freshwater snails, may provide valuable insights for the treatment of chronobiological diseases in the future. The study highlights the flexibility of biological clocks and their potential to change biological rhythms according to dominant environmental cycles.
Overall, the study offers insights into the adaptability and potential divergence of biological rhythms in response to tidal environments. The research provides new information on how genetic and non-genetic changes in biological rhythms occur as organisms adapt to rhythmic environments. This study contributes to the field of chronobiology and sheds light on the role of biological clocks in adaptation to environmental cycles, such as tides, which are essential for the survival of various organisms.