The rusty-necklaced partridge(Alectoris magna)and the chukar partridge(Alectoris chukar)are the most common gamebirds in northern China.Previous comparisons of mitochondrial DNA(mtDNA)have revealed an introgression phenomenon between 2 species of partridge in the Liupan Mountain region of China.mtDNA is maternally inherited,making it difficult to determine the origin of parental genes.We assessed the genetic variation and gene flow between these 2 species of partridges using 8 microsatellite loci as neutral diagnostic markers in 171 samples from the hybrid zone.Our data revealed an extensive divergence of genetic structure between populations of rusty-necklaced partridges and chukar partridges.In this study,we found that 19 samples had been previously morphologically identified as rusty-necklaced partridge were genetically identified as hybrids through Bayesian analysis using STRUCTURE analysis.These hybrids exhibited a mosaic of alleles that were derived from both parental lineages.However,chukar partridges did not present the genotype of the rusty-necklaced partridge.Thus,our findings demonstrate that the hybridization between the 2 species was the result of asymmetrical introgression,with gene flow occurring only from the chukar partridge to the rusty-necklaced partridge.In addition,we also note the high linkage disequilibrium in populations of the rusty-necklaced partridge.These results indicate that although unidirectional introgression did not reduce genetic diversity of the Alectoris partridges,it affected the balance of gene flow between populations.The data from microsatellite DNA prompted our concern about the genetic integrity of the rusty-necklaced partridge.
Himalayan snowcock Tetraogallus himalayensis are distributed in alpine and subalpine areas in China. We used mi- tochondrial DNA control-region data to investigate the origin and past demographic change in sixty-seven Himalayan snowcock T. himalayensis. The fragments of 1155 nucleotides from the control region of mitochondrial DNA were sequenced, and 57 poly- morphic positions defined 37 haplotypes. A high level of genetic diversity was detected in all populations sampled and may be associated isolation of the mountains and habitat fragmentation and deterioration from Quaternary glaciations. In the phylogenetic tree, all haplotypes grouped into four groups： clade A （Kunlun Mountains clade）, clade B （Northern Qinghai-Tibetan Plateau clade）, clade C （Tianshan Mountains clade） and clade D （Kalakunlun Mountains clade）. We found a low level of gene flow and significant genetic differentiation among all populations. Based on divergence time we suggest that the divergence of Himalayan snowcock occurred in the middle Pleistocene inter-glaciation, and expansion occurred in the glaciation. Analysis of mtDNA D-loop sequences confirmed demographic population expansion, as did our non-significant mismatch distribution analysis. In conclusion, limited gene flow and a pattern of partial isolation phylogeographic was found in geographic populations of T. hima- layansis based on the analysis on mtDNA D-loop sequences [Current Zoology 57 （6）： 758-767, 2011].
Xiaoli WANGJiangyong QUNaifa LIUXinkang BAOSen SONG
