Department of Zoology, University of Oxford, Oxford, United Kingdom; Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire, United Kingdom
Christopher G Wilson
Department of Zoology, University of Oxford, Oxford, United Kingdom; Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire, United Kingdom
Pedro Almeida
Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire, United Kingdom; Division of Biosciences, University College London, London, United Kingdom
Institute of Zoology, Section Developmental Biology, University of Cologne, Köln, Wormlab, Germany
Diego Fontaneto
National Research Council of Italy, Water Research Institute, Verbania Pallanza, Italy
Lutz Becks
Community Dynamics Group, Department of Evolutionary Ecology, Max Planck Institute for Evolutionary Biology, Plön, Germany; Aquatic Ecology and Evolution, University of Konstanz, Konstanz, Germany
Fernando Rodriguez
Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA, United States
Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA, United States
Timothy G Barraclough
Department of Zoology, University of Oxford, Oxford, United Kingdom; Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire, United Kingdom
Transposable elements (TEs) are selfish genomic parasites whose ability to spread autonomously is facilitated by sexual reproduction in their hosts. If hosts become obligately asexual, TE frequencies and dynamics are predicted to change dramatically, but the long-term outcome is unclear. Here, we test current theory using whole-genome sequence data from eight species of bdelloid rotifers, a class of invertebrates in which males are thus far unknown. Contrary to expectations, we find a variety of active TEs in bdelloid genomes, at an overall frequency within the range seen in sexual species. We find no evidence that TEs are spread by cryptic recombination or restrained by unusual DNA repair mechanisms. Instead, we find that that TE content evolves relatively slowly in bdelloids and that gene families involved in RNAi-mediated TE suppression have undergone significant expansion, which might mitigate the deleterious effects of active TEs and compensate for the consequences of long-term asexuality.
