[Fluctuations in numbers in box populations of Drosophila and selective genetic mechanism of their regulation].
Box populations of Drosophila melanogaster are characterized by two types of periodical fluctuations of numbers: with low and high frequency. High frequency fluctuations are determined by existence of preimago and imago stages and subsequent delay in density-dependent limitation of imago reproduction, duration of which is determined by time of preimago stage. The period of these fluctuations should be limited within two generation, that is confirmed by experimental data. Low frequency fluctuations with the period of 13-15 generations are the result of ecological density-dependent effect. In this case during pick density one can observe continuous degradation of population (i.e. decrease in fecundity and life time of imago) and following decrease in numbers. Temporary changes in fecundity of females and their offspring of the second generation are positively correlated with low frequency fluctuations in numbers. Such relationships show the possibility of density-dependent, cyclic, genetic changes in fecundity connected with fluctuations in numbers. It means that at the phase of growth in numbers when the density is still low, the selection is directed to the individuals with high fecundity sensible to overpopulation. The phase of decline in numbers is connected with high density and selection directed to the individuals with low fecundity in low density populations. The changes in genetic structure of fluctuating population lead to the weakening of this fluctuations and to the maintaining of population under such conditions.
Grechanyĭ
G V
GV
Institute of Biology, Irkutsk State University, Box 24, ul. Lenina 3, Irkutsk 664003, Russia.
Korzun
V M
VM
Kravchenko
K L
KL
D000822:Animal Husbandry; D000818:Animals; D000830:Animals, Laboratory; D004331:Drosophila melanogaster / Q000235:genetics*; D005260:Female; D005298:Fertility; D005828:Genetics, Population; D008297:Male; D011157:Population Dynamics