Figure 1
From: Proteinortho: Detection of (Co-)orthologs in large-scale analysis
Orthology relations. Idealized dataset for two species A and B. Proteins x ∈ A and y ∈ B are depicted by open boxes. Orthology relations between proteins x and y are represented by grey shadows. Arrows indicate alignments above a certain cut-off from the search of x against B. Solid lines refer to the best alignments. Cases (1), (2), and (3) cannot occur by definition in an idealized dataset, but of course do appear in real life applications.