Community instability in the microbial world

Miniature ecosystems provide insights into general ecological principles From the rainforests that sequester large amounts of carbon ( 1 ) to the gut microbiota that play an important role in the health of the host ( 2 ), ecological communities of all forms and sizes serve valuable functions. Although stable and diverse activities are more likely to be found in communities that are stable and diverse ( 3 ), it is unclear exactly how diversity and stability within communities influence each other ( 4 ). Studying this relationship in large-scale ecosystems, such as the rainforest, is often unfeasible because of practical limitations. On page 85 of this issue, Hu et al. ( 5 ) present observations of bacterial communities under highly controlled conditions. They found that diverse communities lose stability and that this negative effect of diversity on stability is amplified when species in their communities interact strongly. If this applies to natural ecological communities of different scales, human activities that strengthen interactions between species may destabilize certain valuable ecological functions.