Neogene lake systems of Central and South-Eastern Europe: Faunal diversity, gradients and interrelations

The gastropod γ-diversity of 12 Neogene lake systems is evaluated. In total, 1184 gastropod taxa from 119 localities are recorded deriving from the Early Miocene Rzehakia Lake System, the Early to Middle Miocene Dinarid Lake System, Lake Skopje, the Paratethyan Sarmatian lakes and the South German lakes, the Late Miocene Lake Pannon, the Pliocene lakes Dacia, Transylvania, Slavonia, Kosovo and Šoštanj as well as the Holocene Lake Petea. Each lake system is characterised according to its faunistic inventory and endemism. According to their gastropod faunas the lakes may be divided into pyrgulid-, hydrobiid-, viviparid- and planorbid-dominated ones. The generally high endemism rate is between 60 and 98%. Species diversity and generic diversity are strongly correlated. In contrast, neither endemism nor lake size are tightly linked with γ-diversity. Outstandingly high diversities such as observed for Lake Pannon are rather a result of the combined effect of autochthonous evolution in a long-lived system and accumulation of inherited elements. Examples of parallel evolution in lymnaeids and planorbids are presented.