Pattern of Chromosomal Polymorphism During Population and Species Divergence in Chironomus (Diptera, Chironomidae)
I.I. Kiknadze, V.V. Golygina, A.G. Istomina, L.I. Gunderina
Abstract
Karyotypes and chromosomal polymorphisms were studied by analysis of sets and frequencies of polytene chromosome banding sequences in 90 Chironomus species. It was shown that most of Chironomus species investigated have a high level of chromosomal polymorphism. Numbers of banding sequences between karyopools of different species vary from 7 to 60. A karyopool of all 90 species studied includes more than 1200 banding sequences. A clear-cut cytogenetic divergence of natural populations inside the species was established. It was based on different sets and frequencies of banding sequences. The most strong cytogenetic divergence was observed between Palearctic and Nearctic populations of Holarctic species such as Chironomus plumosus and Chironomus entis. Intercontinental cytogenetic distance between populations for these species was 10 times higher than intracontinental one. Palearctic and Nearctic populations of C. tentans have diverged so deep that two sibling-species were formed (Nearctic C. dilutus and Palearctic C. tentans).
The philogenetic ACDEF-tree based on comparison of 315 Chironomus banding sequences in 5 chromosomal arms of 63 species demonstrates a clear correlation between karyotype divergence and species divergence.
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