Fig. 1.—

Phylogenetic origins of mtpt fragments (minimum 500 bp). Darker shading indicates a larger total number of mtpt fragments, with the specific count noted above each branch. Branch lengths were estimated based on a concatenation of four plastid genes (matK, psaA, psaB, and rbcL) using a GTR (REV) substitution model and a molecular clock constraint in baseml (Yang 2007). The reference tree for this figure was based on a maximum-likelihood topology with splits among Silene species and among asterids, caryophyllids, and rosids both collapsed into polytomies.