The Ka/Ks ratio is used to infer the direction and magnitude of natural selection acting on protein coding genes. A ratio greater than 1 implies positive or Darwinian selection (driving change); less than 1 implies purifying or stabilizing selection (acting against change); and a ratio of exactly 1 indicates neutral (i.e.
The Ka/Ks ratio is used to infer the impact and direction of evolutionary forces on protein-coding genes. A ratio greater than 1 suggests adaptive evolution; a ratio less than 1 indicates conservative evolution; and a ratio of exactly 1 signifies no net evolution.