The formation of subspecies in Acridoidea (Orthoptera) in the mountains of Middle Asia.

Abstract

1. The Acridid fauna in Middle Asian mountains is characterized by the fact that the formative process started in the Neogene in relation to orogenesis is being continued nowadays on a large scale. This can be exemplified by the isolation of intraspecies forms in a large number of mountain-dwelling species. - 2. Acridid species in which the process of the formation of geographical races is going on in the mountains can be divided into two large groups. The first includes the species with wide ranges, most of which lie within the lowlands of Eurasia. These are, first of all, the species related to desert, semidesert and steppe landscapes. The second group contains species endemie in Middle Asian mountains. - 3. When the species distributed in the lowlands form special geographical races in the mountains, the formation of these latter follows the principle of the change of habitats (Bey Bienko). - 4. In some cases the formation of subspecies in endemie species is related to the division of the range into certain geographical units, and the ranges of subspecies lie on different ridges of the same mountain system. In other instances subspecies may occur on the same ridge, being always ecologically separated since they occur in different vegetative formations. - 5. The morphogenetic process in the Acridids may run parallel to a similar process in plants dwelling in the same ecological conditions.