Nucleotide Polymorphism and Within-Gene Recombination in Daphnia magna and D. pulex, Two Cyclical Parthenogens

Christoph R. Haag, Seanna J. McTaggart, Anais Didier, Tom J. Little, Deborah Charlesworth

Research output: Contribution to journalArticlepeer-review

Abstract

Theory predicts that. partially asexual organisms may make the "best of both worlds": for the most part, they avoid the Costs Of Sexual reproduction, while still benefiting from an enhanced efficiency of selection compared to obligately asexual organisms. There is, however, little empirical data oil partially asexual organisms to test this prediction. Here we examine patterns of nucleotide diversity at eight unclear loci in continentwide samples of two species of cyclically parthenogenetic Daphnia to assess the effect of partial asexual reproduction oil effective population size and amount of recombination. Both species have high nucleotide diversities and show abundant evidence for recombination, yielding large estimates of effective population sizes (300,000-600,000). This suggests that selection will act efficiently even oil imitations with small selection coefficients. Divergence between the two species is less than one-tenth of previous estimates, which were derived using a mitochondrial molecular clock. As the two species investigated are among the most distantly related species Of the genus, this Suggests that the genus Daphnia may be considerably younger than previously thought. Daphnia has recently received increased attention because it is being developed as a model organism for ecological and evolutionary genomics. Our results confirm the attractiveness of Daphnia as a model organism, because the high nucleotide diversity and low linkage disequilibrium suggest that fine-scale mapping of genes affecting phenotypes through association Studies should be feasible.

Original languageEnglish
Pages (from-to)313-323
Number of pages11
JournalGenetics
Volume182
Issue number1
DOIs
Publication statusPublished - May 2009

Keywords

  • CODON USAGE BIAS
  • LINKAGE DISEQUILIBRIUM
  • DELETERIOUS MUTATIONS
  • DROSOPHILA-MELANOGASTER
  • CAENORHABDITIS-ELEGANS
  • CLONAL DIVERSITY
  • DNA POLYMORPHISM
  • SUBDIVIDED POPULATIONS
  • PLASMODIUM-FALCIPARUM
  • ASEXUAL POPULATIONS

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