An evolutionary perspective
The Romanian karst ocupy almost 2% of the country and is well developed in the Southern and Western Carpathians. The most important karst areas are located in the Apuseni Mountains (in northwestern Romania), the Banat Mountains (in southwest, adjacent to the border with Serbia) and Dobrogea (in southeast Romania, between the Danube and the Black Sea).
The highest diversity among crustaceans in Romanian groundwater is found in the copepods (class: Copepoda; order: Cyclopoida and Harpacticoida) and ostracods (class: Ostracoda; order: Podocopida), represented by more than 160 species and subspecies.
They have been analyzed data from 233 georeferenced records for 164 species of groundwater copepods and ostracods from Romania and used a comparative approach to recognize the determinants of the regional-scale richness, endemism, and distribution patterns, with a primary focus on species from the Carpathian Mountains. In addition, we examined the driving forces for the observed pattern of distribution and richness linked to contemporary (groundwater habitat fragmentation and heterogeneity, climate, vegetation) and historical (past climate and vegetation) environmental conditions.
The analyses showed that species richness was high, irrespective of habitat heterogeneity, in karst and non-karst areas; (2) the main driver accounting for high species richness in the karst landscape was the rainfall regime (> 1350 mm per year), whereas, in non-karst areas, it was woodland vegetation; and (3) there was significant species richness and richness of phyletic lineages in hypothetical forest glacial refugia of the Carpathian arc. The combination of the distribution pattern, diversification, and evolution of stygobite lineages provides reliable evidence for species persistence in the Romanian groundwater during Pleistocene. It is assumed that the south-eastern Europe and especially the Romanian Carpathians were important regions for surface and underground invertebrates survival during glacial periods and acted as a source of post-glacial colonization processes.