An image of the Pando Aspen Grove, the world's largest known single organism, comprising 40,000 trees and covering 106 acres. (Photo courtesy of George Rose via Getty Images)
Researchers have discovered that Pando, a vast quaking aspen tree covering more than 100 acres (40 hectares) in Utah, is not only one of the largest known organisms on the planet, but also one of the oldest.
A new study has found that aspen trees (Populus tremuloides), which reproduce clonally through shoots called ramets, may be between 16,000 and 80,000 years old. The oldest non-cloned organism on Earth is Methuselah (Pinus longaeva), a bristlecone pine that grows in eastern California and is 4,856 years old. Pando’s age estimate is based on the rate of mutations that occur in the aspen genome over time. The study, which has not yet been peer-reviewed, is published on the preprint platform bioRxiv.
There’s a wide range in the estimate, lead study author Roseann Pino, a researcher at the University of Utah, told Live Science, because mutations in aspen are rare, and it’s not clear how quickly those genetic changes accumulate in new shoots and stems. However, analysis of lakebed samples near Pando also showed the continued presence of aspen pollen for more than 60,000 years, suggesting that the lineage may have been around since humans first migrated out of Africa.
“How did this organism survive all the environmental changes it has encountered over time?” Pino asked. “These are really interesting questions to think about.”
Pando is the largest tree in the world. Its name translates as “I spread” in Latin, and it does spread: the organism has given rise to about 47,000 individual stems in the Fishlake National Forest in south-central Utah. All of these stems are connected by a massive underground root system, making Pando the heaviest living organism on the planet.
At this point, there was no hard scientific data on Pando’s age, said Paul Rogers, director of the Western Aspen Alliance, a research and conservation organization. Rogers was not involved in the new study, though he is an adjunct fellow in the University of Utah’s ecology department. “What they found here is a significant step forward,” he told Live Science.
Rogers speculates that Pando’s true age may be closer to 16,000 years old than 80,000, since glaciers advanced about a mile (1.6 kilometers) from where the aspen trees now grow about 20,000 years ago. The aspen trees may have had a hard time surviving in that near-glacial environment, he added. Meanwhile, the lakebed where Pino and her colleagues collected pollen may have collected pollen from a wider area than what covers Pando. Ancient DNA evidence would be needed to confirm that the pollen came from Pando.
Sourse: www.livescience.com
