Mo’orea’s hidden treasure trove of fungi

The tropical islands of the South Pacific are home to immense biodiversity, but their inaccessible environment – jagged peaks, hot and humid conditions and remote locations – have limited the ability to document what exists.

But the secrets of biodiversity are finally being revealed for the Polynesian volcanic island of Mo’orea. Scientists spent months trekking across its tricky terrain to gather specimens as part of the Mo’orea Biocode Project and have presented the first detailed description of the impressive array of fungi that call it home.

Gathering a total of 553 fungal specimens, and sequencing the DNA of 433 of them, they’ve discovered that only a handful are exact genetic matches with other known species. In other words, Mo’orea’s fungi likely contain completely new-to-science species, according to the new study published in the Journal of Biogeography.

The collection includes more than 200 species of macrofungi — that is, fungi producing visible, fruiting bodies.

“It’s like a treasure trove,” says study lead author Matteo Garbelotto, cooperative extension specialist and adjunct professor of environmental science, policy and management at the University of California Berkeley, U.S.

“It’s truly uncharted territory in evolutionary biology and biodiversity of the fungal kingdom, and this is one the first attempts to generate baseline information on fungal diversity, not just for Mo’orea, but for the entire and vast Insular Oceania region.”

The research was part of the Mo’orea Biocode Project, which ran from 2007 to 2010 and aimed to catalogue every form of life larger than bacteria on and around the island – from mountaintops to the sea floor.

The fungal specimens were collected from the soil, roots and leaves of plants, and even the air, then  cultured and compared to databases of new species. As part of the biocode project, the research team also obtained DNA sequences of a specific gene that can be used as a unique “barcode” to differentiate one species from another.

“We were really interested in the biodiversity of the island,” says first author Dr Todd Osmundson, who completed the work as a postdoctoral researcher at UC Berkeley. “Mo’orea is an island in the middle of the ocean, and it’s a geologically young volcanic island.”

“It’s never touched another piece of land. How did fungi get there, and where did they come from?”

The researchers were able to piece together where this incredible fungal diversity had originated from by comparing the DNA sequences of the fungi from Mo’orea to those from other species around the world.

Their findings suggest that the majority of the species, or their ancestors, were carried across the ocean from Australia or other South Pacific Islands by easterly winds, before finally resting on Mo’orea. A small number might have even been brought to the island by humans from far-flung locations like East Asia, Europe, and South America.

Understanding the biodiversity of fungi on Mo’orea and how different species have journeyed around the world to arrive at this remote location can help scientists better understand the ongoing impacts of global travel and trade on biodiversity.