Consider four contemporary taxa numbered 1, 2, 3, and 4.

A total of n shared DNA sites are sequenced for each taxon. Let Nwxyz be the number of sites at which taxon 1 has base w, taxon 2 base x, and so forth. If we denote the three possible unrooted trees by E, F, and G, then we can define three statistics NE =

r∈{A,G,C,T}

s=r Nrrss NF =

r∈{A,G,C,T}

s=r Nrsrs NG =

r∈{A,G,C,T}

s=r Nrssr for discriminating among the unrooted trees. Show that maximum parsimony selects the unrooted tree E, F, or G with largest statistic NE, NF, or NG. Draw the unrooted tree corresponding to each statistic.