ADAPTIVE POLYMORPHISM IN SOIL-INHABITING TESTATE AMEBAS (RHIZOPODA) - ITS IMPORTANCE FOR DELIMITATION AND EVOLUTION OF ASEXUAL SPECIES

The varieties of the soil-inhabiting testate species Trinema complanatum PENARD, 1890, and Euglypha laevis PERTY, 1849 (including Euglypha rotunda WAILES & PENARD, 191 1) are shown to be adaptive morphs of an extreme polymorphism. The morphs represent adaptations in the (upper) litter and the underlying humus horizon in raw humus soils. The morphs of the lifter horizon also occur in Sphagnum where the microhabitat structure is similar to that of litter. In clonal cultures the features of the morphs remain relatively constant. Nevertheless, over the course of several months other morphs occur. The morphs could be transformed into each other by selection. In nature these species have a high ability to manoeuvre ecologically. With the help of known genetic mechanisms this paper proposes a genetic interpretation of the polymorphism of asexual protozoan species, which simultaneously gives understanding of the delimitation and evolution of asexual species.