Table 4. Overrepresentation of testis-biased genes and somatically sex-biased genes among genes with polymorphic expression within D. melanogaster
Significance level of polymorphism TBGs OBGs sMBGs sFBGs
All genes 579 787 55 73
P < 0.05 (%) 543 (94)* 579 (74)* 49 (89) 61 (84)
P < 0.01 (%) 429 (74)* 321 (41)* 38 (69) 49 (67)
  • Significant departures from independence were determined by a G test with 1 df. Both sMBGs and sFBGs are overrepresented among polymorphic genes relative to genes with no somatic sex bias, of which 80% are polymorphic at P < 0.05 and 47% are polymorphic at P < 0.01. These results do not change if a different cutoff is chosen to assign significance to gonad or somatic sex-biased expression. TBGs, testis-biased genes; sMBGs, somatically MBGs; sFBGs, somatically FBGs. *, P < 0.001.