Tree Balance

Abstract

Abstract Hierarchic classifications can differ with respect to tree balance—the degree to which branches divide the subtended taxa into subsets of equal size. Several indices, sensitive to different aspects of tree balance, are compared. Extensions of these indices to multifurcating trees and to trees with varying numbers of OTUs are proposed, and suggestions for employing these indices are furnished. Different tree-forming algorithms may result in trees with differing degrees of balance no matter which index is computed. Tree balance is an important consideration for phylogenetic systematics, because balance of the true phylogeny will affect the accuracy of its estimates.