Ecology of testate amoebae from oligotrophic peatlands: Specific features of polytypic and polymorphic species

Relationships between species abundance and water table depth and soil moisture have been modeled using weighted averaging and species niches have been calculated as optima and tolerance for these parameters. Niche separation of closely related taxa has been examined in detail and it has been shown that there is often a gradient of hydrological preference within each taxon. Wet to dry gradients include those found in the Trigonopyxis arcula group (T. arcula var. major > T. arcula > T. minuta), Assulina-Valkanovia group (A. seminulum > A. muscorum > V. elegans), and Trinema lineare group (T. lineare var. truncatum > T. lineare > T. lineare var. terricola), all of which are associated with a large to small size gradient. In addition, spined forms within the Euglypha and Placocista genera have been shown to consistently occur in wetter habitats than glabrous forms of those with shorter spines. A conclusion has been drawn that palaeoecological studies should cover the lowest taxa possible within these groups to maximize the ecological indicator value of the assemblages recorded.