After examining the evolutionary history of fungi, a world group of scientists has concluded that these organisms appeared between 900 million and 1.4 billion years ago, much sooner than scientists thought. This suggests that fungi were thriving on Earth hundreds of thousands of years before plants began to grow. The results were made possible by open access publishing, advanced analytical methods and recent evolutionary models that mix multiple dating techniques.
Eduard Oka, Ramón and Cajal opened the University of Catalonia (UC).
“As a group, fungi are much larger than previously thought. It is very likely that they were already around a billion years ago, making them one of the oldest major groups of eukaryotes,” Oka said. This signifies that fungi (a kingdom that features mushrooms, molds and single-celled organisms akin to yeast) predate each animals (that are thought to have arisen about 600 to 600 million years ago) and multicellular land plants (about 500 to 500 million years ago).
A revised timeline for the origin of life
Unlike plants and animals, fungi are rarely left behind as fossils due to their soft, thread-like structures. With so few preserved stays, scientists have long struggled to piece together their evolutionary story. To overcome this challenge, the researchers used a mix of three complementary sources: the limited variety of known fungal fossils, genomic sequences from greater than 100 species, and data on horizontal gene transfer—an unusual but revealing process that turned out to be essential to the evaluation.
Horizontal gene transfer occurs when a gene is transferred from one species to a different. “When a gene jumps from one organism to another, it tells us that both existed at the same time. This enables us to establish relative timelines, because any relative of the donor lineage must necessarily be older than any descendant of the recipient lineage of the gene.” By combining evidence from these genetic exchanges with other molecular dating tools and high-speed computational models, the team produced a way more accurate and detailed evolutionary timeline for greater than 100 species of fungi.
Cuki: The first pioneers of life on Earth
These results transcend indicating ancient dates. They reshape our understanding of Earth's early terrestrial ecosystems, that are poorly represented within the fossil record. According to Ekaina, “Our results suggest that fungi were already present on the terrestrial environment not less than 800 million years ago and that they interacted ecologically with the ancestors of multicellular land plants, although we’re currently uncertain in regards to the degree of complexity of those interactions. These ancestors probably acquired close similarities with groups of green rings, a few of that are that are somewhat just like polygamous individuals.
Modern fungi form symbiotic partnerships with most plants, providing them with nutrients in exchange for carbohydrates. These ancient relationships, called mycorrhizae, may date back to a number of the earliest life on Earth. Long before the looks of complex plants, fungi can have helped algae and primitive plants adjust to terrestrial conditions while obtaining recent sources of energy in return. “If we accept that fungi have an important role in helping plants colonize the earth, our theory is that this contribution may have started much further than previously thought, in the environment as biological soil fragments or microbial mats that we still have today,” said Aka Ana, affiliated with the EOC Health Center and the UOC Tech Centre.
Reimagining a once “empty” land
The traditional theory of early Earth depicts a barren planet until plants appeared about 500 million years ago. This study challenges this concept. New evidence suggests that fungi were already energetic for hundreds of thousands of years, interacting with adolescence forms and changing the landscape. By breaking down minerals, releasing nutrients, and helping to form the primary soils, these ancient fungi played a key role in making Earth more hospitable to future life.
The discovery, which relied on close collaboration between experts in evolution, paleontology, and molecular biology, also highlights the importance of heterogeneous innovation. “This idea originated from an innovative tool developed by the Hungarian group of Dr. Garijli J. Szolsi, of which I was a member when I was doing my postdoctoral research. These results would not have been possible without this collaboration or the contributions of researchers from Hungary, England, Japan and Catalonia.”
Opening up recent avenues for research
The team now hopes to use their approach to other branches of complex life to enhance our understanding of evolution as a complete. “Cookies were a huge subject of study, because the scarcity of the fossil record meant that our approach provided significant added value. The next challenge is to extend these techniques to all eukaryotes to develop a much better molecular clock for all complex life,” Oka said.