Illustrative cladogram showing the key protein acquisition and loss events across the major Flaviviridae clades. The two major lineages are labelled (Lin. 1 and Lin. 2), near the root. Each clade, displayed as a tip, is annotated with symbols representing the presence of key proteins. Branches are highlighted to denote the lineage-specific presence of envelope protein E (in light blue) or E1/E2 (in maroon). Major nodes are emphasized with larger symbols to infer the ancestral emergence of each protein within the Flaviviridae . Dashed lines and arrows denote the loss or gain of specific proteins, highlighting potential recombination events and gene transfers. Image of Aquifex pyrophilus by Guillaume Dera; CC BY 1.0 ( https://creativecommons.org/licenses/by/1.0/ ).
