Figure 2From: What happened after the initial global spread of pandemic human influenza virus A (H1N1)? A population genetics approachNumber of influenza sequences of HA (full bars) and NA (empty bars) reported during the initial four months (2A) and for the global analysis (2B), θ values found for the same sequences and periods are seen in figures 2C and 2D, while π values are in figures 2E and 2F.Back to article page