Table 2. Correlation analysis of axis 1 and codon usage index of chloroplast genomes of six Euphorbiaceae plant species.

CAI means codon adaptation index; GC3s indicates the GC content at the third codon position of synonymous codons; L_aa is defined as total number of amino acids.

	Euphorbia esula	Hevea brasiliensis	Jatropha curcas	Manihot esculenta	Ricinus communis	Vernicia fordii
CAI	−0.023	−0.114	−0.035	−0.185	0.152	−0.307*
GC3s	0.421**	−0.320*	−0.581**	−0.352**	0.284*	0.324*
L_aa	0.165	−0.059	−0.020	−0.059	0.068	0.216

Notes.

^*P < 0.05.

^**P < 0.01.