title: Genetic Exchange among Bdelloid Rotifers Is More Likely Due to Horizontal Gene Transfer Than to Meiotic Sex.
abstract: Although strict asexuality is supposed to be an evolutionary dead end, morphological, cytogenetic, and genomic data suggest that bdelloid rotifers, a clade of microscopic animals, have persisted and diversified for more than 60 Myr in an ameiotic fashion. Moreover, the genome of bdelloids of the genus Adineta comprises 8%-10% of genes of putative non-metazoan origin, indicating that horizontal gene transfers are frequent within this group and suggesting that this mechanism may also promote genetic exchanges among bdelloids as well. To test this hypothesis, we used five independent sequence markers to study the genetic diversity of 576 Adineta vaga individuals from a park in Belgium. Haplowebs and GMYC analyses revealed the existence of six species among our sampled A. vaga individuals, with strong evidence of both intra- and interspecific recombination. Comparison of genomic regions of three allele-sharing individuals further revealed signatures of genetic exchanges scattered among regions evolving asexually. Our findings suggest that bdelloids evolve asexually but exchange DNA horizontally both within and between species.
authors.affiliation: Laboratory of Evolutionary Genetics and Ecology, URBE, NAXYS, University of Namur, Rue de Bruxelles 61, 5000 Namur, Belgium.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Debortoli
authors.affiliation: Laboratory of Evolutionary Genetics and Ecology, URBE, NAXYS, University of Namur, Rue de Bruxelles 61, 5000 Namur, Belgium.
authors.forename: Xiang
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire SL5 7PY, UK.
authors.forename: Isobel
authors.initials: I
authors.lastname: Eyres
authors.affiliation: Institute of Ecosystem Study, National Research Council, Largo Tonolli 50, 28922 Verbania Pallanza, Italy.
authors.forename: Diego
authors.initials: D
authors.lastname: Fontaneto
authors.affiliation: Laboratory of Evolutionary Genetics and Ecology, URBE, NAXYS, University of Namur, Rue de Bruxelles 61, 5000 Namur, Belgium.
authors.forename: Boris
authors.initials: B
authors.lastname: Hespeels
authors.affiliation: Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire SL5 7PY, UK; Natural History Museum, Cromwell Road, London SW7 5BD, UK.
authors.forename: Cuong Q
authors.initials: CQ
authors.lastname: Tang
authors.affiliation: Evolutionary Biology & Ecology, Université Libre de Bruxelles, C.P. 160/12, Avenue F.D. Roosevelt 50, 1050 Bruxelles, Belgium. Electronic address: jflot@ulb.ac.be.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Flot
authors.affiliation: Laboratory of Evolutionary Genetics and Ecology, URBE, NAXYS, University of Namur, Rue de Bruxelles 61, 5000 Namur, Belgium. Electronic address: karine.vandoninck@unamur.be.
authors.forename: Karine
authors.initials: K
authors.lastname: Van Doninck
mesh_terms: D000818:Animals; D001530:Belgium; D022761:Gene Transfer, Horizontal; D005828:Genetics, Population; D016678:Genome; D006239:Haplotypes; D008540:Meiosis; D012100:Reproduction, Asexual / Q000235:genetics; D012403:Rotifera / Q000235:genetics*
keywords: HGT; asexuals; cryptic species; gene conversion; haplowebs; recombination