Largest ever global air sampling maps fungal spread

Mushrooms and other fungi spread their spores in a more localised way than once thought and more similar to how animals and plant species migrate, new research has found.

Published in the journal Nature, it is the largest ever global air sampling project and analyses how the climate affects the growth and spread of fungi.

The study used air samplers to collect airborne fungal spores at 47 locations on every continent apart from Antarctica over a two-year period.

Most fungi spread by releasing airborne spores and detection of these spores with air sampling can tell us when they are released and how far they travel.

Mapping of the global distribution of fungi can establish the ecological ranges of rare or threatened species to be observed. This allows us to detect changes in these patterns caused by climate change or habitat destruction.

It also means the spread of fungi which are potentially harmful to humans or crop plants can be monitored.

Fungi are essential to how ecosystems work but they are mostly invisible to the naked eye, so the factors determining their distribution and activity remain poorly understood.

It is estimated that there could be up to five million different species but most of these remain unknown.

For decades scientists debated which factors drive the distribution of fungi and other microbes.

It was originally believed that the long distance dispersal of fungi in the air meant they could reach all parts of the planet, but would only grow in suitable conditions.

This contrasts with animals and plants whose spread is more strictly limited by mountain ranges, seas and other geographical barriers.

However, the new research paper shows that the spread of fungi, like animals and plants, is determined by climatic factors, and that they too are distributed locally, not only in where they grow but in how their spores are spread.

Professor Gareth Griffith from the Department of Life Sciences at Aberystwyth University said:

“Sampling of airborne DNA in the way we have for this study is a huge step forward in the understanding of the how fungi grow and disperse in different parts of the world.  Overall, our results suggest that the factors that affect where microbes live and grow are similar to those determining the distribution of plants and animals.

“The very diverse kingdom of fungi follows globally highly predictable patterns. These patterns resemble those described for other major groups of organisms. This research makes a major contribution to that long-standing debate.”

The study found that species of airborne fungus found in different regions was most strongly affected by the mean annual air temperature of the site, with diversity and numbers increasing from the poles towards the Equator.

The results also confirms that temperature influences fungal reproduction and that spore release peaks when the wind speeds are high.

Professor Gareth Griffith from Aberystwyth University added:

“Our results highlight the role of temperature as an underlying driver of fungal dispersal, with fungal diversity increasing with warmer climates and more spores being released on warmer days. This finding suggests that global climate change, and generally warming climates, will have a major role in restructuring fungal communities.

“Although previous large-scale studies of soil fungi have found clear effects of the climate on community composition, the fact that air temperature explains most of the variation in the distributions of fungi in our data is striking.”

Speaking about the significance of the air sampling, Academy Research Fellow Nerea Abrego, from the University of Jyväskylä in Finland, said:

“Air is a real treasure trove for nature research; it is full of DNA from plants, fungi, bacteria, insects, mammals and other organisms. This knowledge is essential not only to understand where and when different fungal species thrive, but also to predict their fate under the ongoing global change.

“One particularly interesting subject for further research is a more detailed review of the sequences for fungi that are important to humans. These include fungal diseases of humans, crops and production animals, as well as fungi that indicate the progress of the loss of nature and the weakening of natural ecosystem processes.”

The Global Spore Sampling Project was funded through a number of bodies, including the UK Natural Environment Research Council.