Minimum Evolution and Goodness-of-fit

Two criteria are much used to evaluate phylogenetic trees constructed from distance data: goodness-of-fit and tree length. The exhaustive study of trees connecting four taxa shows that in some instances there is a discrepancy between these two criteria. The largest tree may be the one that best fits the distances at the cost of a negative interior branch length, whereas the shortest tree always has the largest interior branch length and is the most supported by nucleotid configurations.