Figure 5.

Evolution of GC Content in Plastomes of Orobanchaceae.

(A) A strong evolutionary trend of reduction in total GC content occurs with the transition from an autotrophic to a parasitic lifestyle and continues in nonphotosynthetic lineages. P values from LRTs at key nodes of lifestyle changes evaluate constant-variance random walk versus directional random walk models to explain GC variation in parasites and nonparasites.

(B) GC content at different codon positions of intact plastid protein-coding genes for nine nonphotosynthetic and four photosynthetic plants.

(C) Variation of GC content at different codon positions in coding regions of parasites and nonparasites assessed as the difference (ΔGC) to a reference genome (Aucuba japonica, Garryaceae). In (B) and (C), a line inside each box designates the median across 31 conserved plastid genes; the whisker ends are at the 5th and 95th percentiles.