The main stages of snow-cock’s evolution and forming of recent areal of species of the genus Tetraogallus

The short review of different theories about origin and evolution of the snow-cocks is given. Author's data supposed the next major points of this evolution. 1. There was one general ancestor of all recent species of genus Tetraogallus, that had all characteristics of snow-cocks, and especially the specific construction of the flying apparatus. That kind of apparatus perfectly adopted to the special flight moving from one slope of the hill or the mountain to another, and named by author as «gliding-diving flight» (Potapov 1966). The peculiarities of color patterns of the feathers show the sharp differences between T. altaicus and T. tibetanus from one side (white-bellied species), and T. caucasicus, T. caspius, T. himalayensis (dark-bellied species) from another side. The analyses of distribution shows that in snow-cock’s history the periods of wide distributions alternated by the periods of decreasing of their ranges. The first ones were caused by the cold periods of the Pleistocene, and the seconds — of «interglacial» periods: the snow-cocks well adopted to cold climate and cannot endure the summer hotness. For this reason they are presented or not in the middle-height mountains. The main events in evolution of this birds are: the origin and spreading form, «prasnow-cocks» (the first cold period of Pleistocene); differentiation of preliminary stock for two branches – white-bellied group and dark-bellied group (during the next warm «interglacial» period); the wide distribution of the representatives of these groups (the second cold «glacier» period); the separating in the way of space isolation, to the modern species (the next warm period); the new distribution of modern species and overlap of ranges of T. tibetanus and T. himalayensis (the Wurm cold period), and, finally, the forming of modern isolated populations of different species (Holocene time). Due to this schedule the age of genus not so old. It covered only the Pleistocene time and the origin and evolution of snow- cocks was formed by two main factors – the global coldness and arising of large mountain systems in Central Asia.