Haploid selection within a single ejaculate increases offspring fitness

Ghazal Alavioon, Cosima Hotzy, Khriezhanuo Nakhro, Sandra Rudolf, Douglas G. Scofield, Susanne Zajitschek, Alexei A. Maklakov, Simone Immler

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30 Citations (Scopus)
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Abstract

An inescapable consequence of sex in eukaryotes is the evolution of a biphasic life cycle with alternating diploid and haploid phases. The occurrence of selection during the haploid phase can have far-reaching consequences for fundamental evolutionary processes including the rate of adaptation, the extent of inbreeding depression, and the load of deleterious mutations, as well as for applied research into fertilization technology. Although haploid selection is well established in plants, current dogma assumes that in animals, intact fertile sperm within a single ejaculate are equivalent at siring viable offspring. Using the zebrafish Danio rerio, we show that selection on phenotypic variation among intact fertile sperm within an ejaculate affects offspring fitness. Longer-lived sperm sired embryos with increased survival and a reduced number of apoptotic cells, and adult male offspring exhibited higher fitness. The effect on embryo viability was carried over into the second generation without further selection and was equally strong in both sexes. Sperm pools selected by motile phenotypes differed genetically at numerous sites throughout the genome. Our findings clearly link within-ejaculate variation in sperm phenotype to offspring fitness and sperm genotype in a vertebrate and have major implications for adaptive evolution.
Original languageEnglish
Pages (from-to)8053–8058
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America (PNAS)
Volume114
Issue number30
DOIs
Publication statusPublished - 25 Jul 2017

Keywords

  • biphasic life cycle
  • sperm selection
  • sperm genotype
  • sexual reproduction
  • gametic selection

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