Genomic evidence for ameiotic evolution in the bdelloid rotifer Adineta vaga

Thumbnail Image
Flot, Jean-Francois
Hespeels, Boris
Li, Xiang
Noel, Benjamin
Arkhipova, Irina R.
Danchin, Etienne G. J.
Hejno, Andreas
Henrissat, Bernard
Koszul, Romain
Aury, Jean-Marc
Barbe, Valerie
Barthelemy, Roxane-Marie
Bast, Jens
Bazykin, Georgii A.
Chabrol, Olivier
Couloux, Arnaud
Da Rocha, Martine
Da Silva, Corinne
Gladyshev, Eugene A.
Gouret, Philippe
Hallatschek, Oskar
Hecox-Lea, Bette
Labadie, Karine
Lejeune, Benjamin
Piskurek, Oliver
Poulain, Julie
Rodriguez, Fernando
Ryan, Joseph F.
Vakhrusheva, Olga A.
Wajnberg, Eric
Wirth, Benedicte
Yushenova, Irina A.
Kellis, Manolis
Kondrashov, Alexey S.
Mark Welch, David B.
Pontarotti, Pierre
Weissenbach, Jean
Wincker, Patrick
Jaillon, Olivier
Van Doninck, Karine
Linked Authors
Alternative Title
Date Created
Related Materials
Replaced By
Loss of sexual reproduction is considered an evolutionary dead end for metazoans, but bdelloid rotifers challenge this view as they appear to have persisted asexually for millions of years1. Neither male sex organs nor meiosis have ever been observed in these microscopic animals: oocytes are formed through mitotic divisions, with no reduction of chromosome number and no indication of chromosome pairing2. However, current evidence does not exclude that they may engage in sex on rare, cryptic occasions. Here we report the genome of a bdelloid rotifer, Adineta vaga (Davis, 1873)3, and show that its structure is incompatible with conventional meiosis. At gene scale, the genome of A. vaga is tetraploid and comprises both anciently duplicated segments and less divergent allelic regions. However, in contrast to sexual species, the allelic regions are rearranged and sometimes even found on the same chromosome. Such structure does not allow meiotic pairing; instead, we find abundant evidence of gene conversion, which may limit the accumulation of deleterious mutations in the absence of meiosis. Gene families involved in resistance to oxidation, carbohydrate metabolism and defence against transposons are significantly expanded, which may explain why transposable elements cover only 3% of the assembled sequence. Furthermore, 8% of the genes are likely to be of non-metazoan origin and were probably acquired horizontally. This apparent convergence between bdelloids and prokaryotes sheds new light on the evolutionary significance of sex.
© The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Nature 500 (2013): 453–457, doi:10.1038/nature12326.
Embargo Date
Nature 500 (2013): 453–457
Cruise ID
Cruise DOI
Vessel Name
Except where otherwise noted, this item's license is described as Attribution-NonCommercial-ShareAlike 3.0 Unported