BRANCH SUPPORT AND TREE STABILITY

TLDR

Branch support is quantified by the extra length required to eliminate a branch in the consensus of near‑most‑parsimonious trees. The method calculates branch support from the original data, weighting extra length for Farris‑weighted trees, and defines a total support index as the sum of branch supports divided by the length of the most parsimonious tree. The resulting total support index quantifies tree stability by measuring supported resolutions, a key metric in cladistic analysis.

Abstract

Abstract— Branch support is quantified as the extra length needed to lose a branch in the consensus of near‐most‐parsimonious trees. This approach is based solely on the original data, as opposed to the data perturbation used in the bootstrap procedure. If trees have been generated by Farris's successive approximations approach to character weighting, branch support should be examined in terms of weighted extra length needed to lose a branch. The sum of all branch support values over the tree divided by the length of the most parsimonious tree[s] provides a new index, the total support index. This index is a measure of tree stability in terms of supported resolutions, which is of prime importance in cladistic analysis.