Nematodes reveal the importance of biodiversity

A predatory female nematode of the genus clarkus under the microscope.
A predatory female nematode of the genus Clarkus under the microscope.
Marcel Ciobanu

Nematodes, or roundworms, are everywhere: from the poles to the tropics, on land and sea, from mountains to mines kilometres below the surface of the Earth.

About 25,000 different species have been described, though some estimates put the likely total number of species at around 1 million. Around 80% of all individual animals alive right now may be nematodes.

Some are parasites. Some are free-living. Some can put their bodies on pause instead of dying when the conditions get too dry or too hot or too cold, and revive themselves if and when they find themselves in more hospitable surroundings. They also play a vital role in almost all ecosystems.

For all these reasons, a study of nematodes can be a proxy for a study of an ecosystem as a whole. 

That’s how a team of ecologists from the German Centre for Integrative Biodiversity Research (iDiv), Leipzig University, and the University of Minnesota used them recently, in a study of the effects of global warming on biodiversity.

In research described in Science Advances, they used heat lamps to artificially raise the temperature of several meadows by around 3°C and recorded the effects on the nematode inhabitants.

They found that in fields that grew only a single plant species, increased temperature led to less diversity in the kinds of nematodes in the field. In fields with many plant species, however, warming led to increased diversity of nematodes.

According to Dr Madhav P. Thakur, the lead author of the study, the lesson is clear: “The story is simple; you need biodiversity to conserve biodiversity in a warmer world.”

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