Molecular evolution of synonymous codon usage in Populus

Table 2 Lineage-specific substitutions at synonymous (S) and non-synonymous (NS) sites, preferred and unpreferred codons (U → P and P → U) and A/T and mutations (W → S and S → W).

Species	S	NS	P → U	U → P	G ^a	d _UP-PU	S → W	W → S	G ^b	d _WS-SW
Pd	292	203	72	102	5.17*	0.172	89	75	1.20	0.085
Pe	561	392	201	181	1.05	-0.052	162	152	0.32	0.032
Pn	282	212	87	84	0.05	-0.018	87	87	0.0	0.000
Pta	548	386	123	227	30.9***	0.297	120	137	1.12	0.066
Ptr	202	120	73	64	0.59	-0.066	36	53	3.24	-0.191
Pd/Ptr	17	49	4	7	0.82	0.273	18	20	0.11	-0.053
Pe/Pta	81	78	33	21	2.67	-0.222	4	12	4.0*	-0.050
Pe/Pta/Pn	54	21	11	6.23*	1.26	0.333	26	31	0.44	-0.087
Total	2037	1461	604	708	8.24**	0.079	559	550	0.07	-0.081

ISSN: 2730-7182