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Microbial research suggests that biodiversity does not always increase ecosystem stability

Although many conservationists believe biodiversity is intrinsically valuable, the protection of biodiversity has also been argued for on the basis that diversity makes ecosystems healthier and more stable. But are highly diverse ecosystems more stable and productive than ecosystems with low diversity?

The question has been investigated in plants and animals, where some evidence suggests a link between biodiversity and various measures of ecosystem function, but few studies have investigated the hypothesis's applicability among microbes, which comprise most of life on Earth and drive many of the planet's biogeochemical cycles.

Yunfeng Yang and colleagues investigated the question by creating microbial communities with between one and 16 Proteobacterial species under control conditions, starvation, or saline stress. Proteobacteria, also known as Pseudomonadota, is a phylum of common and important bacteria.

Using high-resolution growth measurements taken every 30 minutes over 12 days, the authors tracked key indicators of ecosystem function—including maximum specific growth rates, maximum yield, mortality rate, and species interactions. The findings are in the journal PNAS Nexus.

In control conditions, diversity did predict high growth rates and community stability, but this relationship vanished under the stresses of starvation or high salinity. On the contrary, diversity was associated with an increased mortality rate under starvation.

According to the authors, there's likely no single generalizable relationship between diversity and ecosystem functioning or stability.