Spermatogenic expression profiles of new and old genes. (A) Old genes (red) are expected to be mainly expressed in the diploid phases of spermatogenesis, where mitosis occurs; new genes (blue) are expected to be more highly expressed in later phases of spermatogenesis, meiosis, and post-meiosis. (B) Relative proportion calculated separately for old and new D. melanogaster genes overexpressed in mitosis, meiosis, or post-meiosis (Methods). Total sample sizes for old and new genes were 5170 and 260, respectively. (***) P < 0.001, Fisher's exact test. X-linked genes were excluded from these analyses to avoid effects from X-Chromosome inactivation taking place during Drosophila male meiosis (Vibranovski et al. 2009).
