The South Pacific islands are a biodiversity hotspot, but their rugged peaks, hot and humid conditions, and remote locations limit scientists’ ability to document the many fantastic life forms in the region.
In a new study published today in the Journal of Biogeography, researchers from the University of California, Berkeley provide the first detailed description of the impressive variety of fungi that call the Polynesian island of Mo’orea their home. The collection includes more than 200 species of macro fungi – ie fungi that produce visible fruiting bodies – many of which may be new to science.
“It’s like a treasure trove,” said the study’s lead author Matteo Garbelotto, a specialist in cooperative advisory and an associate professor of environmental science, policy and management at UC Berkeley. “It is truly breaking new ground in the evolutionary biology and biodiversity of the fungal kingdom, and this is one of the first attempts to generate fundamental information about fungal diversity, not just for Mo’orea, but for the entire and vast region of Insular Oceania.”
By comparing the DNA sequences of these fungi to those of other species around the world, the team was also able to figure out where the fungal biodiversity on the remote island might have come from. The results suggest that the majority of the species or their ancestors were carried by easterly winds from Australia or other South Pacific islands, although small numbers may have been brought to Mo’orea by humans from as far away as East Asia. Europe and South America.
“We were really interested in the island’s biodiversity,” said study lead author Todd Osmundson, who completed the work as a postdoctoral fellow at UC Berkeley. “Mo’orea is an island in the middle of the ocean, and it’s a geologically young volcanic island. It has never touched any other piece of land. How did the mushrooms get there and where did they come from?”
Understanding both the biodiversity of fungi on the island and how different species traveled around the world to reach this remote place can help scientists deal with the ongoing impact of global travel and trade on deal with biodiversity.
“The Mo’orea BioCode project was the first all-taxa survey of a tropical island to include DNA vouchers and other related information. It included all organisms from marine and terrestrial habitats and everything larger than bacteria,” said George Roderick, William Muriece Hoskins Professor of Environmental Science, Policy and Management at UC Berkeley. “Since then, the data has proven tremendously valuable for monitoring the impact of global change on Mo’orea, but also on other tropical Pacific islands.”
“Every day we had a different challenge”
The Mo’orea Biocode Project was led by Neil Davies, executive director of UC Berkeley’s Gump South Pacific Research Station, and ran from 2007 to 2010. One of the motivations for the project was to create a model ecosystem to be used to answer fundamental questions could ask questions about how ecosystems work.
“Fungi are really important parts of ecosystems,” said Osmundson, who is currently a professor of biology at the University of Wisconsin-La Crosse. “They act as primary decomposers and in some cases (as) pathogens, breaking down decaying organic matter and recycling the nutrients into forms that other organisms can use. They are also very important as symbiotes. They live with other organisms and benefit that organism in exchange for other things. For example, some fungi attach themselves to the roots of plants and exchange nutrients with them.”
To collect the samples, the research team spent months on Mo’orea, beginning each day before sunrise collecting fungal samples from every corner of the ecosystem, including the soil, the roots and leaves of plants, and even the air.
As the heat and humidity increased throughout the day, outdoor conditions often became inhospitable to both the scientists and the delicate fruiting bodies of the mushrooms they collected. In the early afternoon, they brought their specimens back to the lab and began documenting and culturing the specimens found, often staying up late into the night to complete their work.
“The terrain on the island is incredibly steep and when it rains it gets incredibly muddy and many areas are not farmed. So we had a different challenge every day,” said Garbelotto. “There are slopes that you can only really explore on a rope. I remember being pinned to the chasm with my hands outstretched by a rope, trying to collect a mushroom that grew on a small ledge where it was impossible to walk.”
Each of the specimens was photographed and dried for preservation in the university herbarium and compared to databases of known species. As part of the Biocode project, the research team also obtained DNA sequences of a specific gene, which can be used as a unique ‘barcode’ to distinguish one species from another.
“In many ways, Mo’orea is not a pristine island, and that makes it even more interesting to me,” Garbelotto said. “The island has completely untouched areas as well as areas inhabited by humans and profoundly altered, beginning with the arrival of the Polynesians 3,000 years ago and continuing until relatively recently with the arrival of the French, English and Americans. Compared to places that are totally untouched, Moorea is more interesting to me because it’s more representative of what the world actually is.”
Other co-authors of the work include Sarah E. Bergemann of Middle Tennessee State University and Rikke Rasmussen, who did DNA sequencing as a volunteer at UC Berkeley. The Moorea Biocode Project was supported by the Gordon and Betty Moore Foundation.