The parsimonious scenario for COG0572 (Uridine kinase) under the genome-tree topology. The scenario is for g = 1. The designations are is Figs. 1 and 2. The following species name abbreviations are used here and throughout the rest of this work. Eukaryotes: y, Saccharomyces cerevisiae (yeast); archaea: a, Archaeoglobus fulgidus, k, Pyrococcus horikoshii, m, Methanococcus jannaschii or Methanothermobacter thermoautotrophicus, o, Halobacterium sp., p, Thermoplasma acidophilum, z, Aeropyrum pernix; bacteria: b, Bacillus subtilis, c, Synechocystis sp., d, Deinococcus radiodurans, e, Escherichia coli, f, Pseudomonas aeruginosa, g, Vibrio cholerae, h, Haemophiluc influenzae, i, Chlamydia trachomatis or Chlamydophila pneumoniae, j, Mesorhizobium loti, l, Lactococcus lactis or Streptococcus pyogenes, n, Neisseria meningitides, q, Aquifex aeolicus, r, Mycobacterium tuberculosis, s, Xylella fastidiosa, t, Treponema pallidum or Borrelia burgdorferi, u, Helicobacter pylori or Campylobacter jejuni, v, Thermotoga maritima, w, Mycoplasma genitalium or Mycoplasma pneumoniae, x, Rickettsia prowazekii. Pairs of related species designated by the same letter were treated in all analyses as a single entity, i.e. a COG was considered to be present in the respective leaf if it was represented in at least one of these species.