[Microevolutionary changes in populations of Chironomus nuditarsis Str. (Keyl, 1962) (Chironomidae, Diptera) from...

Karyotypes of the Chironomus nuditarsis Str. (Chironomidae, Diptera) (Keyl, 1962) chironomids from central Caucasian populations located at different altitudes above the sea level (a.s.l.) were examined. Specific features of the inversion polymorphism of the high-mountain (more than 1000 m a.s.l.), foothill (500-1000 m a.s.l.), and plain (up to 500 m a.s.l.) populations were identified. A new chromosome banding sequence, ndt F2 (lg-e 7a-8c), which was endemic to Caucasian populations, was described. With the increase in the altitude of the reservoir a.s.l., the decrease in the frequency ofndt G1.2 and ndt B2.2 inversions and the number of inversions per individual and per arm was observed. In the high-mountain population, only the ndt G2.2 homozygotes were detected. The plain population is an interstitial population, while foothill and high-mountain populations are terminal. Cytogenetic distances between the high-mountain and other samples range from 0.174 to 0.223, which is higher than the mean interpopulation value for this species (0.138). The allochrony of the life cycle in aborigines from the foothill population and aborigines from the high-mountain population can be caused by factors such as low high-mountain reservoir temperature. This factor increases the duration of the stages of larvae developmental, which leads to a reduced number of generations and results in a shift in the imago flight and mating timing.