Fig. 1: The population structure of Serratia marcescens.

a SNP-based Maximum Likelihood (ML) phylogenetic tree of the 902 Serratia marcescens strains of the Global genomic dataset. The tree branches’ colours indicate the five clusters coherently and independently determined applying K-means clustering on patristic distances, coreSNP distances and Mash distances. The circle around the tree indicates the strain isolation source (blank if not traceable from the metadata). Bootstrap values are shown on the tree nodes. b Distribution of Average Nucleotide Identity (ANI) between S. marcescens strains within each cluster. The dark blue vertical lines indicate the species identity threshold (95% ANI). c Distribution of Average Nucleotide Identity (ANI) within and between clusters. The dark blue vertical lines indicate the species identity threshold (95% ANI).