Unrooted phylogenies. (top) Maximum parsimony tree of 16S rRNA sequences. (center) Phy-logenetic tree calculated from metabolic network data using the Fitch algorithm for distance matrices. (bottom) Phylogenetic tree calculated from metabolic network data using Splits decomposition with the Fitch-Margoliash power 2 fit for distance matrices. Species abbreviations are collected in Table 1.