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"Treasure trove" of fungi discovered on a South Pacific island

The islands of the South Pacific are well-known for their biodiversity. However, their sharp peaks, hot and humid weather, and remote locations have limited scientists’ ability to properly document the multitude of life-forms inhabiting them. Now, a study led by the University of California, Berkeley has provided the first detailed description of the amazing array of fungi populating the Polynesian island of Mo’orea.

“Fungi are really important parts of ecosystems,” said study first author Todd Osmundson, a professor of Biology at the University of Wisconsin-La Crosse. “They act as primary decomposers, and in some cases as pathogens that break down decaying organic matter and recycle the nutrients into forms that other organisms can use. They’re also really important as symbionts. They live with other organisms and benefit that organism in exchange for other things. For instance, some fungi will attach to the roots of plants and exchange nutrients with them.”

As part of the Mo’orea Biocode Project – which ran from 2007 to 2010 and was the first all-taxa-survey of a tropical island that included DNA details of all marine and terrestrial organisms larger than bacteria – the scientists spent months trekking the island in search of new species of fungi. They gathered a total of 553 specimens and sequenced the DNA of 433 of them. Since only a few of the sequenced specimens have exact genetic matches with other known species, the Mo’orea collections are likely to contain an impressive number of new species.

“It’s like a treasure trove,” said study senior author Matteo Garbelotto, an adjunct professor of Environmental Science, Policy, and Management at UC Berkeley. “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.”

By comparing the DNA of these fungi to those of other species around the world, the scientists found that the majority of the species – or, rather, their ancestors – may have been carried by easterly winds from Australia or other South Pacific islands. 

However, a few of them though may have been brought to Mo’orea by humans travelling from East Asia, South America, or Europe. “In many ways, Mo’orea is not a pristine island, and that actually makes it more interesting to me,” explained Professor Garbelotto. 

“The island has completely pristine areas and also has areas that have been inhabited and deeply changed by humans, starting with the arrival of Polynesians 3,000 years ago and continuing until relatively recently with the arrival of the French, the English and the Americans. Compared to places that are completely pristine, Mo’orea is more interesting to me because it’s more representative of what the world actually is,” he concluded.

The study is published in the Journal of Biogeography

By Andrei Ionescu, Staff Writer

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