The Wollemi Pine is believed to have been extinct for 2 million years until it was rediscovered by a group of hikers in 1994. Now, scientists have decoded its genome to understand how it has survived since the time of the dinosaurs.
The Wollemi Pine (Wollemia nobilis) was rediscovered by a group of hikers in 1994. (Photo: Dave Watts/Getty Images)
In 1994, hikers discovered a group of unusual trees growing in a gorge in Wollemi National Park, located about 100 kilometers west of Sydney, Australia. One hiker reported the discovery to a park naturalist, who subsequently sent leaf samples to a botanist for examination. It was eventually determined that these trees represented an ancient species that had essentially been frozen in time since the age of dinosaurs.
Some have referred to it as a “living fossil.” The Wollemi Pine (Wollemia nobilis) is closely related to preserved remnants dating back to the Cretaceous period (145 million to 66 million years ago). Today, only about 60 such trees remain in the wild, and they are threatened by wildfires in the area. It is believed to have gone extinct around 2 million years ago.
Now, scientists from Australia, the United States, and Italy have decoded the genome of this species, shedding light on its evolutionary process and unique reproductive habits, as well as aiding conservation efforts.
An Unusual Species of Pine
The Wollemi Pine has 26 chromosomes, containing an astonishing 12.2 billion base pairs. In contrast, humans have approximately 3 billion base pairs. Despite their large genome size, the Wollemi Pine exhibits extremely low genetic diversity, indicating a bottleneck (when a population significantly decreases) that occurred about 10,000 to 26,000 years ago.
Indeed, plants do not exchange much genetic material. The remaining trees appear to reproduce primarily through cloning, where shoots emerge from the base and develop into new trees.
Their rarity may partly be due to a high number of transposons or “jumping genes”—segments of DNA that can change their position within the genome. These factors also contribute to the size of the genome.
Gerald Schoenknecht, director of the Plant Genome Research Program at the National Science Foundation, stated: “The smallest plant genome and the largest plant genome have nearly the same number of genes. The significant differences in size often come from transposons.”
When transposons jump to new positions, they can alter sequences within the DNA molecule, thus causing or reversing mutations in genes. They may carry functional DNA with them or alter DNA at the insertion site, significantly impacting the organism’s evolutionary process.
Schoenknecht explained: “In 99% of cases, mutations are probably not a good idea. But over millions of years, 1% helping could advance a species. In this case, it may be an advantage.”
Decoding the genome also revealed why the Wollemi Pine appears to be susceptible to diseases—especially Phytophthora cinnamomi, a fungal pathogen that causes tree death. Unlike most conifer species, the Wollemi Pine has broad needles. This species is classified as critically endangered by the IUCN.
