Fig. 3.
De novo genes originate from nonconserved sequences. (A) The proportions of age 0 genes with identified homologous DNA sequences drop quickly with respect to species divergence in Saccharomyces sensu stricto species. (B) Only a small proportion of age 0 and age 1 genes have homologous DNA sequences in the syntenic regions of age 1 to age 6 and age 2 to age 6 species, respectively. Two different E value cutoffs (10−2 and 10−4) for TBLASTN were applied, but the results were similar. (C) Sequence conservation is lower in regions containing de novo genes (Mann–Whitney test, P value <2.2e-16, ScANCs vs. age 0, or ScANCs vs. age 1). Conservation scores in different groups of CDSs were calculated using orthologous DNA sequences in S. sensu stricto yeasts.