Altai Osmans of the Genus Oreoleuciscus and African Barbs of the Barbus intermedius Complex: the Common Patterns of Morphological Differences between Piscivorous and Non-Piscivorous Forms under Sympatry Conditions

Abstract

In populations of different systematic groups of fish living in lakes of both the same and different continents, the patterns of morphological differences between piscivorous and non-piscivorous ecological forms under sympatric conditions were analyzed. It is shown that, in the Altai osmans of the species Oreoleuciscus potanini in two lakes of the Central Asian Closed Basin, the pattern of differences is almost identical to the pattern of differences between the piscivorous and non-piscivorous forms of barbs of the Barbus intermedius complex sensu Banister (1973) in the African Lake Tana. At the same time, the pattern of differences between the piscivorous and non-piscivorous forms of another species of Altai osmans, Oreoleuciscus humilis, in the lake located in another part of the Central Asian Closed Basin differs significantly from the pattern of differences in ecological forms of both the species O. potanini and the B. intermedius complex. It is assumed that the following explanation may be given for the revealed difference in the variability of osmans in the studied water bodies. In the African Lake Tana and Mongolian lakes Bayan and Khar-Us, the pattern of differences reflects the long-standing situation of stationary coexistence of piscivorous and non-piscivorous forms in the same water body. The pattern of variability in the periodically drying Mongolian Lake Orog reflects not a stable situation, but an incomplete process of its developing interrupted over and over again by the death of the lake population during the next drought period.