Site selection and field sampling

DNA extraction, PCR and sequencing

Sequence filtering

Statistical analysis

Protist freshwater communities show high levels of diversity

High mountain lakes differ from lowland lakes in taxon inventory and act as biogeographic islands

Geographic distance shapes protist distribution patterns and mountain ranges act as barriers to protist dispersal

Protist diversity in European lakes is structured into biogeographic regions

Eukaryotic microbial molecular diversity in European freshwaters

Contribution of biogeography and historical factors to the differentiation of freshwater communities