Genetic structure of Eurasian cattle (Bos taurus) based on microsatellites: clarification for their breed classification.

We pool three previously published data sets and present population genetic analyses of microsatellite variation in 48 Bos taurus cattle breeds from a wide range of geographical origins in Eurasia, mostly its northern territory. Bayesian model-based clustering reveals six distinct clusters: besides a single-population cluster of the Yakutian Cattle from Far Eastern Siberia and a cluster of breeds characteristic of an early origin, the other four major clusters largely correspond to previously defined morphological subgroups of Red Lowland, Lowland Black-Pied, Longhorned Dairy and North European Polled cattle breeds. The results highlighted past expansion events of the productive breeds such as Danish Red, Angeln, Holstein-Friesian and Ayrshire in northern and Eastern Europe. Based on genetic assignment of the breeds and the availability of breed information, we provide a preliminary classification of the five breeds that were to date undefined. Furthermore, in the analysis of molecular variance, despite some correspondence between geographical proximity and genetic similarity, the breed classification appears to be a better predictor of genetic structure in the cattle populations (the among-group variance component: breed classification, 2.47%, P < 0.001; geographical division, 0.77%, P < 0.001).