Keystone concept revisited: insights into microbial community dynamics and control

Different definitions of keystone taxa and functions agree that they have an outsized role in maintaining community composition, and thus, the keystone concept continues to attract attention even 50 years after its introduction. In this Perspective, we base our definition of microbial keystones on the original one to explore its implications and limitations. We review different mechanisms behind keystoneness, cover the strengths and weaknesses of current keystone prediction methods and present findings on keystones discovered in recent experiments. In addition, we suggest a new prediction method for keystones based on metabolic modelling. Finally, we discuss the role of keystones in community control strategies. Overall, the development of new prediction methods and the insights from recent experiments illustrate the continued relevance of the keystone concept for microbial communities.