Origin of duplicates in different vertebrates. The number of duplicates and their origin (in the vertebrate tree) is shown for all organisms analyzed in the current study. (a) The absolute number of duplicated genes; (b) the relative contribution of the origin of duplicates to the total duplicate content of each vertebrate genome. Colors correspond to the duplication events indicated in Figure 2. Pink represents genes of which a major fraction is assumed to have been created during 1R/2R, while orange refers to the fraction of genes of which many are assumed to have been created during the FSGD.