Recombination in a natural population of the bdelloid rotifer Adineta vaga

Sexual reproduction which involves alternation of meiosis and syngamy is the ancestral condition of extant eukaryotes. Transitions to asexual reproduction were numerous, but most of the resulting eukaryotic lineages are rather short-lived. Still, there are several exceptions to this rule including d...

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Published inbioRxiv
Main Authors Vakhrusheva, Olga A, Mnatsakanova, Elena A, Galimov, Yan R, Neretina, Tatiana V, Gerasimov, Evgeny S, Ozerova, Svetlana G, Zalevsky, Arthur O, Yushenova, Irina A, Arkhipova, Irina R, Penin, Aleksey A, Logacheva, Maria D, Bazykin, Georgii A, Kondrashov, Alexey S
Format Paper
LanguageEnglish
Published Cold Spring Harbor Cold Spring Harbor Laboratory Press 17.12.2018
Subjects
Adaptive radiation
Adineta vaga
Asexual reproduction
Chromosomes
Genetic structure
Genetic transformation
Genomes
Genotypes
Homology
Linkage disequilibrium
Meiosis
Natural selection
Population genetics
Recombination
Sexual reproduction
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Summary:Sexual reproduction which involves alternation of meiosis and syngamy is the ancestral condition of extant eukaryotes. Transitions to asexual reproduction were numerous, but most of the resulting eukaryotic lineages are rather short-lived. Still, there are several exceptions to this rule including darwinulid ostracods and timema stick insects. The most striking of them is bdelloid rotifers, microscopic freshwater invertebrates which underwent an extensive adaptive radiation after apparently losing meiosis over 10 Mya. Indeed, both the lack of males in numerous bdelloid species and the lack of proper homology between chromosomes rule out ordinary sex. However, this does not exclude the possibility of some other mode of interindividual genetic exchange and recombination in their populations. Recent analyses based on a few loci suggested genetic exchanges in this group, although this has been controversial. Here, we compare complete genomes of 11 individuals from the wild population of the bdelloid rotifer Adineta vaga, and show that its genetic structure, which involves Hardy-Weinberg proportions of genotypes within loci and lack of linkage disequilibrium between distant loci, is incompatible with strictly clonal reproduction. Instead, it can emerge only under ongoing recombination between different individuals within this species, possibly through transformation. Such a genetic structure makes the population immune to negative long-term consequences of the loss of conventional meiosis, although this does not necessarily imply that interindividual genetic exchanges in A. vaga are directly maintained by natural selection.
DOI:10.1101/489393