Figure 2.

The number of nonsynonymous substitutions per nonsynonymous site (d_N) plotted against the number of synonymous substitutions per synonymous site (d_S) for the D. simulans accessory gland EST library (A), and random nonreproductive proteins (B) compared with D. melanogaster genomic sequence. ● are putative Acps (by differential hybridization or containing signal sequences), whereas ○ cannot be identified as putative Acps by these methods. The line shows the neutral expectation of d_N = d_S. Data for the lower panel are from Moriyama and Powell (44). d_N and d_S were estimated by the maximum likelihood method (50, 51). Similar results are obtained by using the method of Nei and Gojobori (53).