The symbiosis
of plants and fungi has a great influence on the worldwide spread of plant
species. In some cases, it even acts like a filter. This has been discovered by
an international team of researchers with participation from the University of
Göttingen. The results appeared in the journal Nature Ecology & Evolution.
In the colonisation
of islands
by plant species, it isn't just factors like island size, isolation and
geological development that play an important role, but also the interactions
between species. The scientists found that the symbiosis of plant and fungus --
the mycorrhiza -- is of particular importance. The two organisms exchange
nutrients via the plant's fine root system: the fungus receives carbohydrates
from the plant; the plant receives nutrients that the fungus has absorbed from
the soil.
"For
the first time, new data on the worldwide distribution of plant species in
1,100 island and mainland regions allows us to investigate the influence of
this interaction on a global scale," says Dr Patrick Weigelt from the
University of Göttingen's Department of Biodiversity, Macroecology and
Biogeography, who worked on the study. The results: mycorrhiza-plant
interactions, which are naturally less frequent on islands because the two
organisms rely on each other, mean that the colonisation of remote islands is
hindered. The lack of this symbiotic relationship may act like a brake on the
spread of the plants. This is not the case for plant species introduced by
humans, as fungi and plants are often introduced together. Head of Department,
Professor Holger Kreft, adds, "The proportion of plant species with
mycorrhiza interactions also increases from the poles to the equator." One
of the most prominent biogeographic patterns, the increase in the number of
species from the poles to the tropics, is closely related to this symbiosis.
Dr
Camille Delavaux, lead author from the University of Kansas (US), explains,
"We show that the plant symbiotic association with mycorrhizal fungi is an
overlooked driver of global plant biogeographic patterns. This has important
consequences for our understanding of contemporary island biogeography and
human-mediated plant invasions." The results show that complex
relationships between different organisms are crucial for understanding global
diversity patterns and preserving biological diversity. "The absence of an
interaction partner can disrupt ecosystems and make them more susceptible to
biological invasions," Weigelt stresses.
See:
Posted by Dr. Tim Sandle, Pharmaceutical Microbiology
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