Figure 5From: The impact of horizontal gene transfer in shaping operons and protein interaction networks – direct evidence of preferential attachmentDistribution among the COG categories for all the E. coli genes. Counts were estimated for each evolutionary gene category, and expressed as percentages per total number of genes per COG category. The Core, Non-core and HGT gene sets differ in their distribution of COG functional categories (P-value < 0.001).Back to article page