Figure 2

Diagram of two genomic segments containing the genes to be analyzed and their flanking genes. Every box stands for a gene. Boxes g1 and g2 denote members in a family "G" and "fragment X" represents the genomic fragment that contains gene g1 and its neighboring genes and "fragment Y" is the genomic fragment that contains g2 and its neighboring genes. The gray boxes connected by dashed lines represent pairs of homologous genes (a, b, c, d, e) between fragment X and Y. When calculate distance between two adjacent gene pairs, we consider one homologous pair with coordinate (x _i , y _i ) and another pair with (x_i+1, y_i+1) on fragments.