A molecular phylogenetic tree of Type I KS domains from prokaryotic and eukaryotic PKS and FAS, analyzed by Bayesian inference, reveals the diversification of the KS domain gene family. Symbiodinium minutum possesses genes belonging to three major groups within this gene family. Type II PKS and acyl carrier protein synthases (ACPS) were used as outgroups. Numbers at nodes indicate posterior probabilities. Details regarding S. minutum sequences are provided in Table 1. Red stars indicate S. minutum proteins with single PKS-related domains. Green circles indicate S. minutum proteins with multiple PKS-related domains. Dinoflagellate KSs (yellow) are classified as a well-supported group within the protistan Type I PKS clade.