INCONSISTENCY OF THE MAXIMUM-PARSIMONY METHOD - THE CASE OF 5 TAXA WITH A MOLECULAR CLOCK

The inconsistency of the maximum-parsimony method for the case of five taxa with a molecular clock was studied using an analytical approach and Monte Carlo simulation. The inconsistency occurs in the case of a symmetrical tree with short internal branches and long external branch es but can be avoided by using slowly evolving sequences. The neighbor -joining method is consistent if the evolutionary distances between ta xa are estimated accurately. However, for short sequences, estimates o f distances are subject to large statistical errors, and the probabili ty of obtaining a certain erroneous tree by this method can be larger than the probability of obtaining the true tree. The implications for phylogenetic reconstruction are discussed.