Constant differential distribution of genetic variants in polyploid parthenogenetic forms of Lumbricillus lineatus (Enchytraeidae, Oligochaeta)

Abstract

The distribution of variants within the complex species Lumbricillus lineatus was studied throughout a year along two transects on the shore of the Hvide Sande Canal extending from low tide level to just above highest tide level and covering a total distance of only appr. 4.5 m. Parthenogenetic tri-, tetra- and pentaploid cytotypes showed a highly differential distribution. The triploid is the predominant type at the sites highest on the shore, the pentaploid dominates at the two intermediate sites, whereas the tetraploid is most common at the lowest sites. Within the triploid and tetraploid forms, different electrophoretic types also showed a differential distribution along the transects. These distributions were constant both in space (the two transects) and in time (throughout a year). It is concluded that the genetic variants actively select and utilize different subniches within this heterogeneous environment. The general value of observations obtained from parthenogenetically reproducing species is discussed.