Figure 4From: A close-up view on ITS2 evolution and speciation - a case study in the Ulvophyceae (Chlorophyta, Viridiplantae)Phenetic versus phylogenetic approach of species delimitation of two taxa of Acrochaete. A) Phenetic approach, i.e. pair wise comparison without consideration of the plesiomorphic status of the base pair 21/40 in the conserved region of Helix2 (H2) revealed that A. viridis and A. heteroclada differ by only one hCBC (A-U vs. G-U, respectively). In contrast, B) a phylogenetic approach taking the ancestral status (G-C) of the respective base pair into consideration resulted in the difference of one CBC (G-C → A-U) + one hCBC (G-C → G-U) between these two taxa. Whereas the phenetic approach would,- according to the CBC clade concept, regard A. viridis and A. heteroclada to belong to a single CBC clade (and potentially the same species), the phylogenetic approach showed A. viridis and A. heteroclada as two separate species. Base pair 21/40 as well as its plesiomorphic status (both in gray boxes) are mapped on the branches; and the evolving CBC/hCBC are indicated by blue dashed arrows.Back to article page