The world’s oldest moss has seen three mass extinctions — but may not survive climate change.
The genus TakakiaHave you? The highest number of rapidly evolving genesResearchers report that August 9th in Cellular. A decade long study of TakakiaThe Himalayas show that the moss has adapted well to its high altitude habitat, with resistance against extreme cold and intense UV light. But no matter how fast it can tweak its genes, the scientists found, rapidly rising temperatures in the region were associated with a decrease in the moss’s range — a faster decrease than any of the mosses around it.
TakakiaOnly two species of Moss are found in the Himalayas. Both species are found in Japan and the United States, but only together on the Tibetan Plateau of the Himalayas. Both plants are completely different from any other plant species in the world. The evolutionary shoot that contains Takakia branched off the other bryophytes — mosses, liverworts and hornworts — around 390 million years ago.
“The evolutionary position of Takakia in plants is like that of platypus in mammals,” says Yikun He, a plant geneticist at the Capital Normal University in Beijing. Just as the platypus has a lot of strange, not-quite-mammal traits — like egg-laying and a beak — TakakiaThere are a few features that distinguish it from other plants. These include feather-like foliage and the absence of pores which control the flow and exchange of oxygen and CO2.
“It looks very different from other mosses,” says Ralf Reski, a plant biotechnologist at the University of Freiburg in Germany. “For a long time, it was unclear if it was a moss.”
Learn more about the mysterious TakakiaReski, He, and their colleagues conducted a long-term research in the Tibetan Plateau at 4,000 meters or more above sea level.
Over the course of 11 years, researchers collected samples, analysed genomes and collected data on the local ecosystem. They also compared fossils from the past 165 millions years with modern specimens. The team had to evacuate a number of students because they were suffering from altitude sickness. The field sites were accessible only in August and September, and even then, “the climate is unpredictable, and one day may experience spring, summer, autumn and winter,” He says.
The moss may have been able to survive in high altitudes, while humans might not. That’s due in part to its genes. While Takakia sports a genome whose length is average for a bryophyte — just over 27,400 genes — it has the largest known number of fast-evolving genes of any moss, liverwort or hornwort, the researchers found.
TakakiaIt was necessary to have that speed as the Himalayas rose 65 million years before. The mosses were exposed to higher ultraviolet light and lower temperatures as the mountains stretched towards the sky. The mosses had to adapt. They had to adapt. Takakia did.
The new study showed the moss’s ability to withstand solar radiation. When researchers exposed TakakiaIt was not affected by a large amount of UV light. In comparison, mosses in the control group began to die after 72 hours. The hardy moss produces “high amounts of metabolites like flavonoids and polyunsaturated fatty acids to protect against radiation,” Reski says. It also sports genes to enable more efficient DNA repair — essential protection against harmful rays.
TakakiaAlso, they are adapted to extreme temperatures. It can go dormant for eight months of the year while under snow, and gets all of its growth and reproduction done, He says, “in the precious three-to-four-month light window period.”
All of these features evolved from about 50 million years ago to the present, the study showed, without ever changing the moss’s physical appearance compared with fossils of TakakiaAround 165 millions years ago.
But this relatively speedy evolution doesn’t seem to be fast enough to help the moss adapt to Climate Change (SN: 3/10/22).
Reski and He along with their colleagues recorded an average temperature increase of approximately four-tenths degree Celsius during the 11 years that the study was conducted. The coverage of Takakia in their sample population decreased by about 1.6 percent per year — faster than four other local mosses.
Researchers predict that the conditions will be right for a successful rebirth of the human race by the end the 21st Century. TakakiaOnly 1,000 to 1,500 sq km will be available on the planet. By that time, the researchers suspect, the world’s oldest moss could be extinct.
Others are more hopeful about the future of this little moss. Evolutionary biologist S. Blair Hedges says that there are other populations. The Tibetan Plateau is not likely to be the final home of these populations. Takakia-freed, he hopes that the moss could make its way elsewhere.
What’s more, “it’s fantastic to see all these different things known about a single [genus], from the fossil record all the way up to the complete genome,” says Hedges, of Temple University in Philadelphia.
He, Reski and his colleagues are currently cultivating Takakia” We are relocating old moss to other areas in Tibet, in hopes of giving it a new lease of life. “TakakiaIt saw us humans coming,” Reski says. It saw us humans coming,” Reski says. “Now we can learn something about resilience and extinction from this tiny moss.”
