According to a University of Alberta-led research team that used genome sequencing to give these strange creatures their own classification home, about 600 seemingly disparate fungi that never quite fit along the fungal family tree have been shown to have a common ancestor.
“They don’t share any distinguishing characteristics that can be seen with the naked eye that would indicate they belong to the same group. But when you look at the genome, this suddenly appears “Toby Spribille, project principal investigator and associate professor in the Department of Biological Sciences, says
“I imagine these to be the platypus and echidna of the fungal world.”
Spribille, Canada Research Chair in Symbiosis, is referring to Australia’s famed Linnaean classification system-defying monotremes—which produce milk and have nipples, but lay eggs—that were the source of debate as to whether they were even real.
“Though nobody thought our fungi were fake, it’s similar because they all look totally different.”
Their small genomes mean this class of fungi have lost much of their ability to integrate some complex carbohydrates. When we go back to look at each of these fungi, suddenly we see all of them are in a kind of symbiosis.Spribille
Using DNA-based dating techniques, the researchers discovered that this new class of fungi, known as Lichinomycetes, descended from a single origin 300 million years ago, or 240 million years before dinosaurs went extinct.
According to David Daz-Escandón, who conducted the research as part of his Ph.D. thesis, these “oddball” fungi were previously scattered across seven different classes—a high-level grouping equivalent to the groups called mammals or reptiles in animals.
He sequenced 30 genomes with a team of researchers from seven countries to obtain material from fungi and discovered that all classes except one descended from a single origin.
“They were classified, but they were classified into such different parts of the fungal side of the tree of life that people never suspected they were related to each other,” says Díaz-Escandón.
Earth tongues—eerie tongue-shaped fungi that shoot up vertically out of the ground—beetle gut microbes, and a fungus found in tree sap in northern Alberta are all examples of these fungi. They also include some unusual lichens that can survive in harsh environments such as South America’s Atacama Desert, the world’s driest non-polar desert.
“What’s really fascinating is that, despite their appearance, these fungi have a lot in common at the level of their genomes,” says Spribille. “No one saw it coming.”
The team predicts that this group of fungi is dependent on other organisms for survival based on their genomes, which are small in comparison to those of other fungi.
“Their small genomes mean this class of fungi have lost much of their ability to integrate some complex carbohydrates,” said Spribille. “When we go back to look at each of these fungi, suddenly we see all of them are in a kind of symbiosis.”
He believes the new findings will contribute to the larger study of fungal evolution, specifically how fungi acquire important biotechnological features like enzymes that break down plant matter.
The new group may also provide new information about past fungal extinctions. “We believe that the diversity we see today is likely just the tip of the iceberg that survived. And there aren’t many examples of this kind of thing in fungi.”