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Table 2 Test for positive selection and identification of positively selected sites

From: Selection, diversity and evolutionary patterns of the MHC class II DAB in free-ranging Neotropical marsupials

Species Substitution rate ω = d N /d S Model [100] 2(Lb-La) P Positively selected sites
  d N d S      26 37 57 60 70 71 74 77 86
G. microtarsus 0.159 0.178 0.893 M1 – M2a 63.46 <0.001 x x x x x x x x x
  (± 0.028) (± 0.039) n.s. M7 – M8 56.01 <0.001 x x x x x x x x x
     Dist. to human ABS    2 0 1 0 0 0 0 1 0
M. incanus 0.143 0.183 0.781 M1 – M2a 13.32 <0.005   x     x    
  (± 0.026) (± 0.047) n.s. M7 – M8 11.50 <0.005      x x    
     Dist. to human ABS     0    0 0    
  1. The rates of non-synonymous (d N ) and synonymous (d S ) substitutions were calculated for the entire sequence. In the analyses of positively selected sites, twice the difference in likelihood 2(Lb-La) between the models was compared with a τ2-distribution (df = 2) to assess significance [100]. x represents sites under positive selection identified at the >95% confidence level. Sites in bold are antigen binding sites (ABS) according to the human DR1 molecule [37], distance (dist.) to human ABS corresponds to the amino acid distance between identified site and the nearest human ABS.