Table 7.

Results from COEVOL analysis of plastome features among selected leafy, autotrophic species (Spiranthes sinensis, Dendrobium acinaciforme, Triphora trianthophoros, Sobralia callosa, Holcoglossum flavescens and Nervilia fordii) and leafless, heterotrophic species (Didymoplexis pallens, Aphyllorchis montana, Pogoniopsis schenckii, Epipogium aphyllum, Gastrodia elata, Epipogium roseum and Wullschlaegelia calcarata). Numbers above the diagonal are correlation coefficients, with boldface numbers having significant posterior probabilities of <0.05 (negative correlation) or >0.95 (positive correlation).

	d S 1	d N 2	Length3	CDS4	IR-L5	tRNA6	RTT7	GC8	Rep-209	Msat10	DCJ11
d S	1.00	0.96	−0.89	−0.86	−0.37	−0.81	0.84	−0.68	−0.04	0.71	0.70
d N		1.00	−0.87	−0.85	−0.39	−0.76	0.81	−0.61	−0.03	0.64	0.65
Length			1.00	0.92	0.47	0.91	−0.91	0.78	0.06	−0.79	−0.82
CDS				1.00	0.37	0.83	−0.90	0.69	0.23	−0.67	−0.70
IR-L					1.00	0.32	−0.31	0.21	−0.43	−0.35	−0.49
tRNA						1.00	−0.84	0.91	0.21	−0.89	−0.87
RTT							1.00	−0.75	−0.15	0.69	0.73
GC								1.00	0.21	−0.88	−0.78
Rep-20									1.00	−0.10	−0.03
Msat										1.00	0.84
DCJ											1.00

¹Synonymous substitution rate. ²Non-synonymous substitution rate. ³Length of the plastome in base pairs. ⁴Number of putatively functional protein coding genes. ⁵Length of inverted repeat in base pairs. ⁶Number of putatively functional tRNA genes. ⁷Root-to-tip branch lengths under the GHOST heterotachy model with six rate mixture classes. ⁸GC content of the plastome. ⁹Proportion of the plastomes composed of dispersed repeats >20 bp in length. ¹⁰Proportion of the plastome characterized by microsatellite DNA. ¹¹Double-cut-and-join distance, or the number of structural inversions in the plastomes.