Clone diversity of Eiseniella tetraedra (Oligochaeta: Lumbricidae) along regulated and free-flowing boreal rivers

Abstract

We have sampled populations of the parthenogenetic and polyploid earthworm Eiseniella tetraedra along the Ume, Vindel and Sävar Rivers in northern Sweden. The Vindel River is one of the last free-flowing large rivers in NW Europe, while the Ume River, which flows parallel to it, is harnessed with twenty major dams. Clones were identified on the basis of overall enzyme phenotypes that were detected using starch gel electrophoresis. We found that clone pool diversity is higher along the Vindel River than along the Ume River and the clone pool similarity is, in a similar fashion, higher along the free-flowing river. Evidently the dams stop effectively clone dispersal along the Ume River. Clone diversity is highest at the river mouth. The small free-running Sävar River had also high clone diversity at the lower course of the river. Clone turnover between years is high. We found no evidence for parallel adaptation of clones along the two rivers.