Evolutionary relationships of the organisms used in this study.

<p>The selected organisms represent all major eukaryotic and prokaryotic lineages along the tree of life. Colored boxes in the different tree nodes correspond to the colors used in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0068854#pone-0068854-t001" target="_blank">Table 1</a>. Species names shown in grey were examined in a previous study <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0068854#pone.0068854-Dimitriadis1" target="_blank">[5]</a> based on which we have excluded the Rhizaria from the analysis as there is not enough sequence data and the Amoebozoa as the two completed available genomes have already been analyzed for fusion events by this method. The tree is based on the model proposed by Dacks and Field <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0068854#pone.0068854-Dacks1" target="_blank">[49]</a>; the tree is schematic i.e. the order of the branching events delineating organismal relationships is retained, but distances are not drawn to scale for clarity of presentation.