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Table 3 Responses of GC1 and GC2 to changes in GC3, by domain

From: A simple model based on mutation and selection explains trends in codon and amino-acid usage and GC composition within and across genomes

  n   R 2 Slope ± SE Y at GC3 = 0 ± SE Y at GC3 = 100 ± SE
Bacteria 311 GC1 0.91 0.370 ± 0.007 0.367 ± 0.004 0.737 ± 0.003
   GC2 0.80 0.219 ± 0.006 0.291 ± 0.004 0.510 ± 0.003
Archaea 28 GC1 0.85 0.38 ± 0.03 0.35 ± 0.02 0.73 ± 0.02
   GC2 0.60 0.16 ± 0.03 0.30 ± 0.01 0.45 ± 0.01
Eukaryotes 257 GC1 0.57 0.24 ± 0.01 0.402 ± 0.008 0.643 ± 0.007
   GC2 0.38 0.15 ± 0.01 0.334 ± 0.007 0.482 ± 0.006
  1. Because there is error in both axes, but there should be a definite causal relationship between GC3 and GC1 or GC2, we use model I regression to predict specific values of GC1 or GC2 from a set value of GC3, and thus to calculate the most likely proportion and GC content of constant sites [73].