ИСТИНА

For a long time Middle Amurland in Russia was considered as an exclusive zone of overlap between P. minor and P. major. This zone which formed about hundred years ago as a result of counter expansion of two races continued to change especially during last decades due to further eastern expansion of major (Nazarenko et al., 1999). To evaluate the modern state of interaction between sympatric populations we studied phenotypic major, minor and hybrids using species-specific marker of mitochondrial DNA (Kvist et al., 2003; mtDNA) and original marker of nuclear DNA (nDNA). The proportions of nDNA- heterozygotes were equal among phenotypic major and minor (22,6% n=203 and 24% n=25, respectively). The proportion of birds with foreign mtDNA was higher in phenotypic minor (19.2%, n=26) than in major (4,8%, n=206). In spite of high rate of genetic introgression assuming hybrid status of two contacting populations, both races tend to maintain their morphological peculiarities in the zone of overlap. The difference in introgression rates detected by two independent molecular markers in phenotypic major could be explained by autumn flow-out of major (mainly, females) in south direction and forming of hybrid population in the northern China. Such hypothesized population may serve as a source of phenotypic minor which colonize each spring Russian part of Amurland.