Rare taxa in the core microbiome

Rare taxa are an important constituent of the microbiome and play a crucial role in maintaining biodiversity and ecosystem dynamics. However, little is known about rare taxa within the core microbiome (i.e., core rare taxa), nor do we understand the factors that drive their distribution and occupancy in ecosystems. In this opinion article, we define and explore the role of core rare taxa and the ecological and genetic drivers of their persistence. We also discuss 'innate' and 'adaptive' resilience in relation to core rare taxa and their drivers. Finally, we emphasize the need to develop appropriate metrics to quantify core rare taxa and their functions, as this can have significant implications for biodiversity conservation and microbiome engineering in the long run.