Fungi took root on land long before plants ever did

Fungi may have evolved between 900 million and 1.4 billion years ago. That finding places them on land long before plants, reshaping the timeline of early ecosystems.

The conclusion hinges on new dating approaches that pull more signals from sparse evidence.

The study was conducted by an international, multidisciplinary team. Contributors include evolutionary biologist Eduard Ocaña, a researcher at the Universitat Oberta de Catalunya (UOC).

Their work uses new methodologies and sophisticated evolutionary models that combine several dating techniques to re-examine when fungi first appeared.

Fungi’s billion-year head start

“As a group, fungi are much older than previously imagined. It’s highly likely that they were already around over a billion years ago, making them one of the oldest major groups of eukaryotes,” Ocaña said.

If so, the fungal kingdom – which spans mushrooms, molds, and single-celled yeasts – predates animals, thought to have arisen around 600 million years ago, and multicellular land plants, which arrived roughly 500 million years ago.

This pushes a major branch of complex life further back in time. It also implies that early soils and nutrient cycles on land had fungal players long before roots spread across continents.

Reconstructing life’s missing record

Fungi do not fossilize easily. Their bodies are delicate and fibrous, so the rock record offers only scattered traces. That scarcity has left big gaps in their story.

To close them, the team combined three complementary lines of evidence: the small number of known fossils, genomic data from over a hundred fungal species, and signals from horizontal gene transfers.

These transfers are rare but revealing. “When a gene jumps from one organism to another, that tells us that the two existed at the same time,” Ocaña said.

“This enables us to establish relative timelines, because any relative of the donor lineage must necessarily be older than any descendant of the lineage that received the gene.”

By anchoring evolutionary trees with these chronological markers – and by using new computational tools to cut calculation times – the researchers produced tighter, more reliable timelines for over a hundred fungal lineages.

Early partners in shaping land

The implications go beyond dates. They change how we picture Precambrian landscapes, where fossils are scarce and the mix of eukaryotes is murky.

“Our findings show that fungi were already present on land environments at least 800 million years ago and had ecological interactions with the ancestors of multicellular land plants, although we’re currently unsure about the degree of complexity of these interactions,” Ocaña said.

“These ancestors probably shared similarities with the green algae groups that are evolutionarily closest to multicellular land plants, some of whose members have some degree of adaptability to non-aquatic environments.”

Today, most plants pair with fungi in mycorrhizal relationships. Fungi trade nutrients for plant-made carbohydrates. Those partnerships may be ancient.

“If we accept that fungi were instrumental in helping plants colonize Earth, our theory is that this partnership may have started much earlier than previously thought, in environments similar to biological soil crusts or the microbial mats that we still have today,” Ocaña added.

Fungi prepared Earth for life

The familiar story says continents were barren until plants arrived around 500 million years ago. This work paints a busier scene. Multicellular land plants emerged long after their unicellular ancestors.

By then, fungi were already interacting on land, breaking rocks, recycling nutrients, and seeding the earliest soils. That activity would have made environments more welcoming for later plant invasions, setting the stage for terrestrial ecosystems.

The scope of the collaboration also mattered. The project brought together evolutionary biologists, paleontologists, fungal specialists, and computational tool builders.

“These findings wouldn’t have been possible without this collaboration or the contributions made by researchers from Hungary, England, Japan and Catalonia,” Ocaña said.

A clearer clock for life

The approach is transferable. If horizontal gene transfers can pin dates for fungi, they can help elsewhere, too.

“Fungi were a great subject of study, because the scarcity of fossil records meant that our approach provided significant added value. The next challenge is to extend these techniques to all eukaryotes to develop a much finer molecular clock for all complex life,” Ocaña said.

That would allow scientists to recalibrate the histories of other major groups, align timelines across the branches of the tree of life, and test long-standing assumptions built on fragmentary fossils.

Fungi likely arose hundreds of millions of years earlier than most timelines have assumed. They were active on land well before plants took hold, shaping soils and cycling nutrients in deep time.

By weaving fossils, genomes, and gene transfer clues into a single framework, the study offers a clearer clock for a kingdom that rarely leaves a trace – while opening the door to re-dating much more of life’s past.

The study was published in the journal Nature Ecology & Evolution.

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