CLONE POOL STRUCTURE AND MORPHOMETRIC VARIATION IN ENDOGEIC AND EPIGEIC NORTH-EUROPEAN PARTHENOGENETIC EARTHWORMS (OLIGOCHAETA, LUMBRICIDAE)

Clone pool structure of four ecologically dissimilar parthenogenetic e arthworms (Lumbricidae) was studied by means of enzyme electrophoresis in Sweden, Finland and Estonia. Each Octolasion cyaneum population ha d only one clone (=electrophoretic overall phenotype) but the clones d iffered from each other. Separate populations probably originate from one or few founder worms or cocoons unintentionally introduced by man. In Aporrectodea rosea the clonal heterogeneity was high. This is prob ably due to a high rate of unintentional in addition to parthenogeneti c ones. Sweden and Estonia share 38% of the A. rosea clones and 49% of the A. rosea individuals with the same genotype whereas the correspon ding figures between Finland and Estonia and between Finland and Swede n were lower. There is evidently some clone flow between the countries . These inter-regional clones are most probably southern immigrants in to the area. The clone pool diversity of two epigeics namely Eiseniell a tetraedra and Dendrobaena octaedra was high but clone pool similarit ies between the countries were, on average, lower than they were in A. rosea. In E. tetraedra the highest similarity was found between Finla nd and Sweden but in D. octaedra between Sweden and Estonia as well as Finland and Estonia. These differences can be explained by the differ ent post-glacial dispersal patterns of the clones. Intraspecific diffe rences in somatic traits and secondary reproductive organs between the countries were found, too. The study shows that parthenogenetic earth worms with a continuous geographical range by the Baltic Sea actually comprise populations which differ considerably in their genetical make -up and morphological and morphometric traits. The differences can bes t be explained by dissimilar post-glacial immigration and adaptation.