Comparative analysis of ISSR marker polymorphism in populations of yak (Bos mutus) and in F1 hybrids between yak and cattle in the Sayan-Altai region

The genetic variability in seven yak populations from the Sayan-Altai region and in F₁ hybrids between yak and cattle (khainags) was investigated with the help of a technique that involves the use of inter simple sequence repeat (ISSR) markers generated with PCR primers (AG)⁹C and (GA)⁹C. Samples for the analysis were collected in Mongolia, Tuva, and Altai from 2008 through 2012. The examined yak populations differed in in the presence/absence of ISSR fragments, as well as in their frequency. In total, 46 ISSR fragments were identified using two marker systems; the proportion of polymorphic loci constituted 76% and 90% for the AG-ISSR and GA-ISSR markers, respectively. For the total sample of yaks, total genetic diversity (H _t), within-population diversity (H _s), and interpopulation diversity (G _st) constituted 0.081, 0.044, and 0.459 for the AG-ISSR and 0.137, 0.057, and 0.582 for the GA-ISSR markers, respectively. Based on ISSR finger-printing, species- and breed-specific DNA patterns were described for the three groups of animals (yaks, cattle, khainags). For the domestic yak, the species-specific profile was represented by eight ISSR fragments. Genetic relationships between the yak populations, cattle breeds, and khainags were examined with the help of four different approaches used in the analysis of population structure: estimation of phylogenetic similarity, multidimensional scaling, principal component analysis, and cluster analysis. Clear evidence on the differentiation of the populations examined at the interspecific, as well as at intraspecific, level were obtained. Similar (relative), as well as remote (isolated), yak populations were identified. Khainags occupy an intermediate position between yak and cattle. However, the data on the ISSR-PCR marker polymorphism (genome polymorphism, population structure) indicate that part of the analyzed khainag genome was more similar to the yak genome than to the cattle genome.