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Asexual but Not Clonal: Evolutionary Processes in Automictic Populations.

Abstract

Many parthenogenetically reproducing animals produce offspring not clonally but through different mechanisms collectively referred to as automixis. Here, meiosis proceeds normally but is followed by a fusion of meiotic products that restores diploidy. This mechanism typically leads to a reduction in heterozygosity among the offspring compared to the mother. Following a derivation of the rate at which heterozygosity is lost at one and two loci, depending on the number of crossovers between loci and centromere, a number of models are developed to gain a better understanding of basic evolutionary processes in automictic populations. Analytical results are obtained for the expected neutral genetic variation, effective population size, mutation-selection balance, selection with overdominance, the spread of beneficial mutations, and selection on crossover rates. These results are complemented by numerical investigations elucidating how associative overdominance (two off-phase deleterious mutations at linked loci behaving like an overdominant locus) can in some cases maintain heterozygosity for prolonged times, and how clonal interference affects adaptation in automictic populations. These results suggest that although automictic populations are expected to suffer from the lack of gene shuffling with other individuals, they are nevertheless, in some respects, superior to both clonal and outbreeding sexual populations in the way they respond to beneficial and deleterious mutations. Implications for related genetic systems such as intratetrad mating, clonal reproduction, selfing, as well as different forms of mixed sexual and automictic reproduction are discussed.

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  • Publisher Full Text
  • Authors+Show Affiliations

    School of Biological Sciences, The University of Queensland, Brisbane, 4072, Australia j.engelstaedter@uq.edu.au.

    Source

    Genetics 206:2 2017 Jun pg 993-1009

    MeSH

    Animals
    Biological Evolution
    Clone Cells
    Diploidy
    Heterozygote
    Meiosis
    Models, Genetic
    Mutation
    Parthenogenesis
    Reproduction, Asexual
    Selection, Genetic

    Pub Type(s)

    Journal Article

    Language

    eng

    PubMed ID

    28381586