Size matters: Non-LTR retrotransposable elements and ectopic recombination in drosophila

Dmitri A. Petrov, Yael T. Aminetzach, Jerel C. Davis, Douda Bensasson, Aaron E. Hirsh

    Research output: Contribution to journalArticlepeer-review

    Abstract

    The Drosophila melanogaster genome contains approximately 100 distinct families of transposable elements (TEs). In the euchromatic part of the genome, each family is present in a small number of copies (5-150 copies), with individual copies of TEs often present at very low frequencies in populations. This pattern is likely to reflect a balance between the inflow of TEs by transposition and the removal of TEs by natural selection. The nature of natural selection acting against TEs remains controversial. We provide evidence that selection against chromosome abnormalities caused by ectopic recombination limits the spread of some TEs. We also demonstrate for the first time that some TE families in the Drosophila euchromatin appear to be only marginally affected by purifying selection and contain many copies at high population frequencies. We argue that TEs in these families attain high population frequencies and even reach fixation as a result of low family-wide transposition rates leading to low TE copy numbers and consequently reduced strength of selection acting on individual TE copies. Fixation of TEs in these families should provide an upward pressure on the size of intergenic sequences counterbalancing rapid DNA loss through small deletions. Copy-number-dependent selection on TE families caused by ectopic recombination may also promote diversity among TEs in the Drosophila genome.
    Original languageEnglish
    Pages (from-to)880-892
    Number of pages12
    JournalMolecular Biology and Evolution
    Volume20
    Issue number6
    DOIs
    Publication statusPublished - 1 Jun 2003

    Keywords

    • Copy number maintenance
    • Ectopic recombination
    • Transposable elements

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