Distribution of biomineralization and transporter genes in eukaryotic groups. Summary table of the presence of silica biomineralization, calcium biomineralization and Si-related transporter genes herein examined in selected eukaryotic groups (taxonomic classification based on Adl et al. 2012, italics signify incertae sedis). Black circle = extensive/widespread biosilicification, gray circle= minor/limited biosilicification, white circle = biosilicification absent. Gray shading denotes where genomic or transcriptomic data was available for analysis; asterisks mark where data from that lineage was only available from non-siliceous species. Symbols are placed in taxa where relevant genes were detected; blanks indicate gene not detected and are not a definitive statement of absence. 1 = Group 1, 2 = Group 2; double for SIT, single for SIT-L (see fig. 4). L = Lsi2-like, P = pink-eye dilution-like, Int = intermediate type (see fig. 6). The simplified phylogeny (based on fig. 1) is annotated with our hypothesis for the SIT repertoire (circled) of the eukaryotic LCA, and at the base of each eukaryotic supergroup. This interpretation is based on the ancestral origin hypothesis that assumes vertical inheritance in major groups rather than HGT (see Discussion). Question marks identify supergroups where no SITs or SIT-Ls have been confirmed thus far. Note that Group 2 SIT-Ls are today only found in the SAR supergroup; however, the lack of robust phylogenetic support for the branches separating Group 2 SITs/SIT-Ls from the eukaryotic LCA and the uncertain position of the root (fig. 4) means we cannot rule out a Group 2 origin in the eukaryotic LCA (marked by the 2? symbol) based on our present results. Silicified structures: CW = cell wall, Cys = cysts, Gr = granules, Lor = lorica, Mp = mouthparts, Phy = phytoliths, Sc = scales, Sp = spicules, T = test, Tb = tablets,? = uptake evidence for unknown Si utilization; brackets indicate that is a Si minor component of composite biomineralized structure. The “Ca?” column reports instances of calcification with a tick (Faber and Preisig 1994; Knoll 2003; Knoll and Kotrc 2015). References: 1. Lahr et al. 2013; 2. Sperling et al. 2010; 3. Monniot et al. 1992; 4. Carlisle 1981; 5. Karlson and Bamstedt 1994; 6. Bone et al. 1983; 7. Hua and Li 2007; 8. Williams 1998; 9. Desouky et al. 2002; 10. Leadbeater 2015; 11. Nicholls and Durrschmidt 1985; 12. Patterson and Durrschmidt 1986; 13. Patterson and Durrschmidt 1988; 14. Conforti et al. 1994; 15. Preisig 1994; 16. Chopin et al. 2004; 17. Fuhrman et al. 1978; 18. Millington and Gawlik 1967; 19. Hodson et al. 2005; 20. Durak et al. 2016; 21. Drescher et al. 2012; 22. Yoshida et al. 2006; 23. Foissner et al. 2009; 24. Sen Gupta 2003; 25. Anderson 1986; 26. Ogane et al. 2010; 27. Anderson 1994; 28. Febvre-Chevalier 1973; 29. Mizuta and Yasui 2012.