Gene duplications and gene losses mapped on the vertebrate tree. The vertebrate tree is shown with branch lengths proportional to time. The divergence times were taken from [35,68,69]. Abbreviations of species names are as in Figure 1. The numbers in colored circles indicate the different time points analyzed, referred to in the text as TPx. The total number of inferred duplications at each time point (TP) is shown in italics. The (negative) bars on the plots (with gray background) show the fraction of genes that was lost again after they have been created in a specific duplication event (indicated in colors corresponding to the time points (TP)). The total amount of gene loss for each organism is indicated under the species name.