Mock sequence similarity networks. Weighted sequence similarity networks displaying sequences as nodes (black nodes represent environmental sequences, red nodes represent sequences of cultured ciliates), connected by edges reflecting their %ID obtained from a BLAST analysis (see list of weighted edges in which the color code reflects the %ID; red for 99%, orange for 97%, pink for 96%). The corresponding color code is used on the networks (right panel) to explore and structure the data. The mock dataset results in: A) two connected components when the minimum %ID required to connect two nodes is ≥97%; B) a single giant component when the minimum %ID required to connect two nodes is ≥96%; C) finer-level structure within components can be further detected using methods of community clustering, such as the Louvain Communities (see Methods). %ID, % identity.