Figure 2.

Gains (coloured dashes) and losses (ellipses) of post-synaptic proteins reconstructed onto the taxon phylogeny under the parsimony criterion. Placozoans are here placed as the sister-group to other metazoans. The total number of gains + losses is 45 (see less parsimonious reconstructions obtained for alternative placements of placozoans in Additional file 6). Events are labelled in bold when the corresponding gene orthology is supported by at least two confidence criteria in addition to gene tree topology (see explanations in Methods); otherwise they are labelled in normal font.