Figure 4From: A new look at an old virus: patterns of mutation accumulation in the human H1N1 influenza virus since 1918Mutation accumulation in porcine H1N1. Solid line = porcine regression. Dashed line = the human regression line from Figure3. There is considerably more variability among the porcine versions of H1N1, and there was a significant difference in the two slopes (ANCOVA, p=0.0001).Back to article page