Fitness Costs of Doc Expression Are Insufficient to Stabilize Its Copy Number in Drosophila melanogaster

• DOI: 10.1093/molbev/msg087
• Publication Date: 2003-04-23T21:55:37Z
• Authors: H.-P. Yang
• Keywords: Retrotransposon; Ectopic expression

The stable coexistence of transposable elements (TEs) with their host genome over long periods time suggests TEs have to impose some deleterious effect upon fitness. Three mechanisms been proposed account for the caused by TEs: gene interruptions TE insertions, chromosomal rearrangements TE-induced ectopic recombination, and costly expression. However, relative importance these remains controversial. Here, we test specifically if expression accounts fitness cost imposed insertions. In retrotransposon Doc, requires binding RNA polymerase internal promoter. If Doc is host, copies promoters would be more strongly selected against persist in population shorter compared Docs lacking promoters. We tested this prediction using sequence-specific amplified polymorphism (SSAP) analyses. populations two types sets lines Drosophila melanogaster: selection-free isogenic accumulating new insertions isogenized isofemale sampled from a natural population. found that (1) there no difference proportion promoter-bearing promoter-lacking between lines, (2) site occupancy distribution does not skew toward lower frequency copies. Thus, selection appear stronger than Our results show playing major role stabilizing copy numbers.