Table 1. Number of fixed differences and shared polymorphisms and the ratio of shared polymorphisms to fixed differences between S. meliloti and S. medicae protein coding genes.
| HGT | Genes | Fixed differences | Shared polymorphisms | Ratio | |
| Chromosome | No | 2719 | 273,091 | 390 | 0.0015∶ 1 |
| Yes | 1 | 19 | 8 | 0.42∶1 | |
| pSymA/pSMED02 | no | 230 | 25,480 | 246 | 0.0010∶ 1 |
| yes | 75 | 563 | 1,964 | 3.49∶ 1 | |
| pSymB/pSMED01 | no | 940 | 107,991 | 354 | 0.003∶ 1 |
| yes | 21 | 383 | 567 | 1.48∶ 1 |
Genes are separated by genomic location and whether they bore a signature of horizontal gene transfer (HGT).