Phenotypic variation within histocompatibility-defined clones of marine sponges.

Nongenetic phenotypic variation can be identified by its occurrence within genetically uniform clones. A histocompatibility bioassay of clonal identity was used to ascertain the extent of phenotypic variation within natural clones of two species of marine sponges. Multiple morphological forms of the sponge Aplysina fistularis were found to occur within single clones, indicating a nongenetic polymorphism. In contrast, a genetic basis is suggested for a polymorphism of Aplysina cauliformis; within single clones of this species, individuals were uniform in color and morphology.