Time-course analysis. The composition of microbial communities can change dramatically over time, high-lighting the need for temporal profiling in order to incorporate the (sometimes substantial) longitudinal dynamics of microbial communities into analyses. For example, high- temporal- resolution 16S rRNA gene sequencing has been used to assess the stability of the human gut, oral and skin microbiomes32. Over a time-scale of approximately 1 year, these communities tended to maintain small, stable core members and non-core members that persisted for variable periods. Tracking microbiome development in human infants is another topic of great interest, particularly in cases in which nor-mal development is disrupted by medical intervention in early life33. For example, longitudinal WMS sequenc-ing of an infant delivered by caesarean‑section revealed an early gut microbiome dominated by skin-associated microorganisms; however, the metabolic environment of the infant gut appeared to select against these early colonizers during the first months of life34.