Fig. 4

Expansion of the FSD/MSD (iron/manganese superoxide dismutase) gene family after retroposition. Maximum likelihood tree of the homologous gene group including FSD/MSD genes is shown on left. FSD genes in the Volvox/Chlamydomonas lineage derived from retroposition followed by loss of parental gene in the common ancestor and experienced two duplication events in Volvox lineage. VCA - Volvox; CRE - Chlamydomonas; CSP - Chlorella. Values in each OTU indicate length of encoded protein (aa), number of exons, number of coding exons, and gene name as annotated in the Phytozome database. Bootstrap support values (≥60 %) for the calculated tree are shown on branches. Predicted evolutionary events are projected on the phylogeny. The MSD clade is collapsed and the number of collapsed sequences is shown within it. The tree was rooted using midpoint rooting approach. Synteny conservation of neighboring genes (five upstream, five downstream) of the FSD genes is shown to the right with each color representing homologous genes