The contest between parsimony and likelihood

In a “classic ” phylogenetic inference problem, the ob-served taxa are assumed to be the leaves of a bifurcat-ing tree and the goal is to infer just the “topology ” of the tree (i.e., the formal tree structure linking the extant taxa at the tips), not amount of time between branch-ing events, or amount of evolution that has taken place on branches, or character states of interior vertices. Two of the main methods that biologists now use to solve such problems are maximum likelihood (ML) and maxi-mum parsimony (MP); distance methods constitute a third approach, which will not be discussed here. ML seeks to find the tree topology that confers the highest probability on the observed characteristics of tip species. MP seeks to find the tree topology that requires the fewest changes in character state to produce the characteristics of thos