Table 1. dN/dS ratios in the HERV-K(HML2) family and related exogenous β retroviruses
One-ratio model (=1)
Two-ratio model (=2)
Family Gene Whole tree Internal branches* Terminal branches Likelihood difference (2 - 1) P value
HERV-K(HML2) (44 elements) All 0.52 0.21 0.67 142 <0.001
gag 0.53 0.28 0.68 26 <0.001
pol 0.47 0.16 0.62 91 <0.001
env 0.62 0.26 0.79 31 <0.001
Exogenous viruses (7 elements) All 0.10 0.10 0.10 0.01 NS
gag 0.09 0.09 0.10 0.05 NS
pol 0.07 0.06 0.08 0.67 NS
env 0.17 0.14 0.18 0.85 NS
  • * Excluding the segmentally duplicated clade (see Table 3).

  • Taken from critical values on the χ2 distribution. NS, not significant.