The extent of functional redundancy changes as species' roles shift in different environments

It is currently unclear how biodiversity loss affects ecosystem functioning. The concept of functional redundancy implies that species loss is compensated by other species contributing similarly to functioning. Functional redundancy can be revealed by the relationship between biodiversity and ecosystem functioning (e.g., biomass growth). The functioning of an ecosystem remains unaffected if redundant species are removed but decreases if the removed species have unique roles. Most research on biodiversity-ecosystem functioning (BEF) relationships hitherto was restricted to one single set of environmental conditions. Using a microbial model system, we explored this relationship in different environments. We found that the environmental conditions are pivotal when drawing conclusions about functional redundancy because BEF relationships drastically differ due to changing species roles and interactions.