Figure 1

Consensus secondary structure models of ITS2 in the Ulvales. A) Consensus ITS2 diagram based on 86 sequences covering five families (Kornmanniaceae, Bolbocoleonaceae, Ulvaceae, Capsosiphonaceae and Gomontiaceae). B) ITS2 consensus of the Capsosiphonaceae and Gomontiaceae (41 sequences analyzed), showing extremely high conservation. Nucleotide letters shown in both ITS2 diagrams (A, B) refer to the most frequently occurring character states among the analyzed taxa, obtained via 70% majority rule consensus sequences. Positions without 'dominant' character state among the investigated Ulvales were integrated as circles, or flagged as expansion segments. Invariable positions were drawn in black, whereas for variable positions, the conservation/variability level was quantified by the number of evolutionary changes during the diversification of the Ulvales, and indicated by various colors (nucleotides and/or circles in ochre, blue, or red). 129 positions were present in all studied Ulvales, and were used for a 'universal' numbering system of ITS2 positions. The 'non-universal' positions were labeled with subscript numbers, combined with the previous 'universal' position number. Gray shades indicate the conserved parts of helices 2 and 3 [6]. Several comments in the Figure refer to non-homoplasious CBCs (black frames), inserted positions characteristic for selected taxa, and the length variation of expansion segments. The CBC/hCBC homoplasy background in the ITS2 diagram (A) is indicated by ochre/blue/pale pink shades with the restriction to positions with CBCs/hCBCs/CBCs+hCBCs respectively. C) Simplified ITS2 diagram of Kornmannia displaying a unique, additional helix between helices 3 and 4.