Figure 4
Variation in nucleotide composition at 4FD sites of protein-coding genes in relation to the position of each gene within the genome. Data are presented for: 1) the mean of all four vermetid genomes (diamonds) and 2) Dendropoma maximum alone (squares). The position of each protein encoding gene was calculated as the number of nucleotides from the beginning of nad1 (or nad6 for D. gregarium) to the midpoint of the target gene. This different start point for D. gregarium was based on the derived translocation of nad6 to a position directly upstream from nad1 in this taxon [18]. Regression equations are as follows. All four genomes: Y = -2.92 × 10-4 X + 40.20, r2 = 0.21[%T]; Y = 2.59 × 10-4 X + 24.47, r2 = 0.18 [%A]; Y = 4.84 × 10-4 X + 10.60, r2 = 0.79 [%C]; Y = -4.51 × 10-4 X + 24.73, r2 = 0.56 [%G]; D. maximum alone: Y = -2.45 × 10-4 X + 44.22, r2 = 0.07 [%T]; Y = 8.66 × 10-4 X + 15.47, r2 = 0.78 [%A]; Y = 4.83 × 10-4 X + 6.63, r2 = 0.55 [%C]; Y = -1.10 × 10-3 X + 33.67, r2 = 0.65 [%G].