Gene gain, loss and duplication, and positive selection. Core-genome phylogenies of Streptococcus (left), S. agalactiae (middle), and S. pyogenes (right) based on concatenated genes. Dashed lines correspond to unresolved branches. Numbers adjacent to angle brackets facing the branch refer to genes gained, opposite direction - genes lost, and '×' refers to duplicated loci. Values correspond to the most parsimonious unambiguous changes, following an equally penalized model (that is, gain, loss and duplication events cost the same numbers of changes). Numbers adjacent to the red dot correspond to the number of genes under positive selection within the core-genome, on a particular lineage.