Page 81 - University of Pretoria RESEARCH REVIEW 2016

FAIRY CIRCLES
SOLVING ONE OF EARTH’S LITTLE MYSTERIES
The origins and causes of Fairy Circles remain mysterious; several hypotheses have been pursued but none of the explanations are confidently conclusive.
Fairy Circles are vegetation-free circular patches of soil, ranging from 2m to over 10m in diameter, surrounded by a grass matrix. These enigmatic features were, until their recent discovery in the Australian outback, thought to be endemic to
the Namib Desert in southern Africa. Alternative hypotheses to explain these phenomena range from UFO landings (!), to mythical underground dragons and dancing fairies, local soil geochemistry or radioactivity, plant self-organisation and social insect ecosystem engineering activities.
Dr Jean-Baptiste Ramond and his team from the Centre for Microbial Ecology and Genomics of the University of Pretoria, and in collaboration with Professor Don Cowan, have their own theory.
They have been investigating one of the original hypotheses, which, like UFOs and dancing fairies, has never been satisfactorily proven (or disproved). This hypothesis is that plant-pathogenic microorganisms are involved in the Fairy Circles phenomenon. The big difference in their approach is that Ramond and his collaborators are bringing the latest molecular and phylogenetic techniques to bear on the problem.
Their recent published research has proven that archaeal, bacterial and fungal communities inside Namib Desert Fairy Circles are significantly different to those outside, in the surrounding vegetated soils. They have also shown clear differences for both the Namib gravel plain and dune Fairy Circles.
Even more striking has been the discovery that
over 60 different fungal species are repeatedly only found in soils inside Fairy Circles, and that many of these are affiliated to well-known phytopathogenic fungal groups (such as the Periconia, Culvularia and Aspergillus genera, the Pleosporales order, and the Chaetomiaceae family). This does not yet confirm that these fungi are the pathogenic causative agents of Fairy Circles, but it is a good start.
Ramond and his collaborators are now combining state-of-the-art functional ‘omics’ technologies (heavyweight techniques such as shotgun metagenome sequencing and metaproteomics),
with the latest spatial ecology methods. Remote sensing drone technologies, thanks to a collaboration with researchers from the Auckland University of Technology, New Zealand, are being used to analyse Fairy Circle distribution patterns, growth rates and growth patterns – and even the thermal differences in Fairy Circles and the surrounding vegetated soils.
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Don Cowan