In the shadow of the mighty Himalayas, a resilient moss has silently thrived for millions of years. Takakia, a genus of moss believed to be among the oldest living plants on Earth, has witnessed the rise and fall of dinosaurs and the formation of mountain ranges. However, this ancient survivor now faces a new challenge: climate change.
A Living Fossil
Takakia comprises two species, T. ceratophylla and T. lepidozioides, which are found growing together exclusively on the Tibetan plateau. These mosses also exist in isolated populations in Alaska and British Columbia, their presence there shrouded in mystery.
Unraveling the Secrets of Takakia
Scientists, led by Ralf Reski from the University of Freiburg in Germany, embarked on a decade-long expedition to the Himalayas, trekking through altitudes above 4,000 meters to study Takakia. Their efforts culminated in the sequencing of the genome of T. lepidozioides, shedding light on the evolutionary history and unique adaptations of this ancient moss.
A Rare Moss with Rapidly Evolving Genes
Takakia belongs to a group of plants called bryophytes, which includes mosses, liverworts, and hornworts. Previously, researchers were uncertain about the classification of Takakia within the bryophyte group. However, the newly sequenced genome confirms that Takakia is indeed a rare moss. In fact, it possesses the highest number of fast-evolving genes ever recorded in a plant.
Adapting to Extreme Environments
Takakia’s genome provides insights into its ability to survive in extreme environments. While externally, the moss appears unchanged since it was fossilized 165 million years ago, internally, it has rapidly evolved. The researchers identified 121 genes that have undergone significant evolution, enabling Takakia to adapt to its harsh surroundings. One notable adaptation is the moss’s higher lipid content, which helps it resist the harmful effects of ultraviolet radiation from intense sunlight at high altitudes.
The Decline of a Living Fossil
Despite its remarkable resilience, Takakia is now in decline. Over the past decade, populations of the moss on the Tibetan plateau have decreased by 1.6% annually, a faster decline compared to other local mosses. The International Union for Conservation of Nature’s Red List of Threatened Species classifies T. ceratophylla as globally vulnerable.
Climate Change as a Threat
Climate change is considered a significant factor contributing to Takakia’s decline. As the Himalayan range uplifted around 50 million years ago, the moss’s habitat experienced increased ultraviolet radiation, lower temperatures, and more snow. These changes necessitated adaptations for survival. However, the rapid increase in temperature in recent years, averaging almost 0.5 °C per year between 2010 and 2021, poses a new challenge for Takakia.
The Complexity of Decline
While temperature is a likely factor in Takakia’s decline, other environmental changes such as air quality and humidity may also play a role. Bryophytes, including Takakia, are sensitive to these changes. The exact reasons behind the moss’s decline are still unknown, highlighting the need for further research.
Preserving a Living Record
The ancient genome of Takakia serves as a valuable genetic record. It provides insights into the evolutionary history of mosses and highlights the deep genetic diversity within this ancient plant. The genome also acts as a historical manuscript, safeguarding the genetic information of T. lepidozioides in case of its extinction.
Conservation Efforts
Reski and his colleagues aim to collaborate with researchers studying Takakia populations outside the Tibetan plateau to gain a better understanding of the moss’s adaptations. This knowledge will inform conservation plans to protect this rare and vulnerable species. Given Takakia’s limited dispersal abilities and its specialization to specific niches, conservation efforts are crucial for its survival.
Conclusion
Takakia, an ancient moss that has defied the test of time, now faces the threat of climate change. Its ability to adapt to extreme environments and it’s rapidly evolving genes make it a fascinating subject of study. However, the decline of Takakia on the Tibetan plateau highlights the vulnerability of specialized organisms in the face of environmental changes. Conservation efforts are essential to protect this living fossil and preserve its genetic legacy for future generations.