Evolutionary dynamics in the fish faunas of the Mediterranean basin during the Plio-Pleistocene

摘要

The creation of a database including 243 taxa of teleostean fishes (ichthyoliths and otoliths) from the Lower Pliocene-Middle Pleistocene fossil record of the Mediterranean basin, allowed tracking of the diversity trend; assessment of origins, extinction, and turnover rates; and construction of hypotheses on the settlement mechanisms of the modern Mediterranean fish fauna. These processes have been analyzed with respect to two different time scales: the classic chronostratigraphic units and standard time units of equal duration (24 units of 200,000 years). In the Pleistocene, during the maximum intensity of glacial events and the most intense effects on the Mediterranean areas, the composition of the fish fauna had already developed a clear Mediterranean character (about 75% of the taxa). The residual elements (extinct and extramediterranean) underwent a further strong impoverishment at the Lower-Middle Pleistocene boundary with the Mediterranean component reaching 89.4%. On the basis of the observed trends, and particularly on the basis of the progressive changes in the taxonomic composition of these communities, from the upper Miocene to the present, the idea of a "paleomediterranean" fauna is discussed.