ADAPTIVENESS OF INVERSION POLYMORPHISM IN CHIRONOMUS-PLUMOSUS (DIPTERA, CHIRONOMIDAE) - SPATIAL-DISTRIBUTION OF INVERSIONS OVER SPECIES RANGE

Data on inversion polymorphism in more than 60 natural Chironomus plum osus populations from Europe and Asia are reviewed. Band sequences in chromosome arms A, B, C, and D are analyzed. The results demonstrate t he absence of distinct clinal variation in this parameter. The maximum number of heterozygotes is characteristic for the central part of the range. Peripheral populations demonstrate increasing homozygosity and substitution of standard sequences of bands by alternative sequences. Each peripheral population is characterized by an individual combinat ion of homozygous inversions in arms A, B, C, and D. Adjacent populati ons often differ from one another in frequencies and combinations of h omozygous band sequences located in different chromosome arms. These d ata suggest that the type of manifestation of chromosome polymorphism in natural Ch. plumosus populations depends largely on their local env ironment rather than on geographic gradient.