Title: Paternal sex in parthenogenetic planarians: a tool to investigate the accumulation of deleterious mutations
Abstract:Abstract Clonally reproducing organisms are expected to accumulate slightly deleterious mutations, and this has been demonstrated in RNA viruses, bacteria and unicellular algae. In this paper we prese...Abstract Clonally reproducing organisms are expected to accumulate slightly deleterious mutations, and this has been demonstrated in RNA viruses, bacteria and unicellular algae. In this paper we present evidence for increased embryo mortality in obligate parthenogenetic strains of the freshwater flatworm Schmidtea polychroa, possibly indicating the action of deleterious mutations. The inheritance of this fitness defect was tested by crossing parthenogens with sexuals. This is possible because both forms are simultaneous hermaphrodites that produce fertile sperm. The resulting sexual offspring showed significantly increased embryo mortality in comparison to offspring of a sexual × sexual cross. Alternatives to a mutation explanation of these results, like the degeneration of male traits in parthenogens, are being discussed. In conclusion, these results lend support to the hypothesis that sex is advantageous to a multicellular organism because it prevents the accumulation of deleterious mutations.Read More