Figure 1.

Influence of HGT, gene loss, and gene duplication on phylogenetic and taxonomic distribution of gene families. Three different hypothetical evolutionary scenarios are shown for gene family evolution within a simple four-taxon species tree: (i) in the absence of HGT, gene loss, or gene duplication, the gene tree has the same topology as the species tree (ii) a combination of HGT and gene loss yields a gene tree with a different topology to the species tree (iii) a combination of gene loss and gene duplication yields a gene tree with a different topology to the species tree, with the same gene tree topology as for scenario (ii).