ISSR Analysis Of The Populations In The Hybrid Zone Of The Two Species In Alectoris

Both Alectoris chukar and Alectoris magna are the indicated birds of arid and semi-arid environment in northwest China. A. magna is endemic to China. Some populations of A. magna have expanded their range to regions because of the environmental changes such as recent deforestation by humans in southern Gansu, and have colonized to form new edge populations. Despite ethological isolation between A. chukar and A. magna, hybrids have been identified in some populations of A. magna by molecular markers. Telling the hybrids apart from A. magna based on visual inspection is difficult because of their morphologically similar to A. magna. The hybrid zone is about 80 km wide and 150-200 km long. ISSR is used widely in the genetic research because of its efficient retrieval. Here we employed ISSR (inter-simple sequence repeat) markers to identify genetic diversity, genetic structure of populations in the hybrid zone of the two species. 138 individual belonging to 15 different populations of the two species were surveyed.35 primers were screened and 13 primers were selected to survey all the populations of each taxon. We scored the bands which were clear and reproducible to analysis in POPGENE, NTSYS, ARLEQUIN and TFPGA. The results were shown as follows: a total of 337 bands were scored, of which 330 bands were polymorphic. The percent of polymorphic bands (PPB) was 97.92%. The genetic diversity index ranged from 0.1818±0.1995 to 0.2530±0.1803. Edge populations of A.magna possessed a low level genetic diversity and that was opposite to A.chukar. The average genetic diversity index of A. magna was larger than A.chukar that may be introgression which had great impact on the genetic structure of natural populations. The low value of Gst indicated that most of the genetic variability resided within populations. High level Nm suggested a sufficient genetic exchange and low genetic divergence among populations. The results from AMOVA showed that genetic variability focused on intra populations, in good agreement with the results of POPGENE (Gst = 0.2142). We performed a cluster analysis of all populations using unweighted pair group method with arithmetic averages (UPGMA) from NTSYS. The dendrogram produced by UPGMA cluster analysis demonstrated that A.magna and A.chukar clustered independently and the hybrids clustered' with A. magna. That might be the nuclear gene of female parent had been substituted because hybrids backcrossed with A. magna. The correlation between genetic distance and geographic distance (produced by Google earth software) was small. That also proved large Nm among populations.Only six loci were relative to gene flow and introgression which also proved gene flow from A. chukar to A. magna. During the conservation process, A. chukar should be forbidden to import into the range of A. magna, which prevented A. magna from genetic assimilation and resulting in local genetic extinction. ISSR is dominant marker, which limits the use of itself. Future work focuses on increasing population sampling and other developed informative molecular markers to identify the hybridization in hybrid zone.