Overview of FH2 domain phylogeny. A schematic summary of an unrooted maximum likelihood tree based on 287 FH2 domain sequences (for a full tree see Additional file 3, for a full list of genes and species, see Additional file 1). The remaining 8 FH2 sequences from our collection were either incomplete or found only during the final database checks; for these cases, closest relatives are shown in Additional file 1. Symbols at branches denote percentual bootstrap values (out of 500 replicates; shown for major branches only). Branches supported also by at least 51% of bootstrap replicated in a tree constructed using the NJ method are denoted by green symbols. Clades on a gray background correspond to previously known metazoan or fungal formin classes, clades on a green background to novel multi-species formin clades outside plants (a non-ascomycete fungi group encompassing Phybl1-3, Phybl5-7, Pospl2 and Um2; a stramenopile group including Tp1-6, Phatr1-4 and Pr5, 6; a ciliate clade consisting of Pt1-10 and Tt1-3). Gene name abbreviations are shown for PTEN-containing formins outside plant Class II (sand-colored background) and for yeast and metazoan outliers.