Geographic and ecological patterns in Turkish land snails

The distribution of Turkish land snails has been examined, using data from a monograph by H. Schütt (1993). Turkey has been divided into eight regions for purposes of describing localization of fauna. On average, species occupy 1.7 regions. About 36% of the fauna is known from Turkey alone. There are affinities with Europe, the Caucasus, the eastern Mediterranean and the Levant and Middle East. The influence of neighbouring faunas shows up when the similarities of the eight regions are clustered. As usual, the fauna contains a high spired and a discoidal mode of shell shape, with species covering a wide range of sizes. Clausiliacea occupy a higher mode than other high spired species, while Helicacea become progressively more equidimensional from small to large species. The pattern of shell size and shape varies between regions, smaller and high spired species being most common in cooler and damper parts, larger discoidal species in parts with Mediterranean or continental dry climates. A test for evidence that animals of the same shape and size are more likely to be allopatric than sympatric failed to show that they were. The fauna is dominated by a few families to a greater extent than that of Europe, and is more like that of the isolated Madeiran archipelago. It is suggested that the Turkish fauna still shows evidence of external penetration with some local radiation, in the manner of the oceanic islands, and has not evolved to become a balanced assemblage such as is seen in Europe.