Figure 2

Mapping of the probability vector onto an equilateral triangle. Each QuartOP is represented as a probability vector P inside an equilateral triangle. The position of P is determined by the barycentric coordinates (p₁, p₂, p₃), which correspond to the posterior probabilities or bootstrap support values of the three possible tree topologies. The vertices of the triangle T₁, T₂ and T₃ represent the three possible unrooted tree topologies. Geometrically, each of the coordinates (p₁, p₂, p₃) equals the distance between P and the side of the triangle opposite the corresponding vertex. Points closer to a vertex T_i have a larger corresponding probability p_i and represent a more probable tree topology than the two alternatives. All the points are classified by their position in one of three zones: "total" zone, "90%" zone and "99%" zone, which are depicted schematically and not drawn to scale. In this diagram, point P corresponds to a dataset which has highest probability for the topology T₃, but the probability is below 90%, so the point P is located in the "total" zone, but not in the 99% or 90% zone. Figure adapted from [24].