Genetic variation in Symbiodinium (= Gymnodinium ) microadriaticum Freudenthal, and specificity in its symbiosis with marine invertebrates. I. Isoenzyme and soluble protein patterns of axenic cultures of Symbiodinium microadriaticum

Abstract Axenically culturedSymbiodinium (=Gymnodinium) microadriaticum Freudenthal, isolated from 40 host individuals (or colonies) representing 17 species in two phyla were resolved into 12 strains, each strain having a unique combination of four isoenzyme patterns as revealed by starch gel electrophoresis. Each individual host appeared to contain an electrophoretically homogeneous population of algae. Each characteristic isoenzyme pattern was maintained after re-isolation of a cross-infecting strain (i. e. a strain that had been experimentally introduced into a host of a species other than that from which it was originally isolated), indicating a genetic basis for the protein patterns observed in each strain. The strains could be separated into three groups after constructing a dendrogram by the unweighted average linkage clustering method based on calculations of similarity coefficients. Soluble protein patterns obtained from the algae were also strainspecific. A dendrogram constructed from data obtained by analysis of protein patterns resolved by a polyacrylamide gel disc electrophoresis was similar to the dendrogram constructed from the data on isoenzyme patterns, but suggested that the ‘phenetic’ distances between strains were larger than indicated by the isoenzyme patterns.