Sutter Andreas, Lindholm Anna K
Proc Biol Sci. 2015 Jul 22;282(1811). doi: 10.1098/rspb.2015.0974.
Female multiple mating (polyandry) is widespread across many animal taxa and indirect genetic benefits are a major evolutionary force favouring polyandry. An incentive for polyandry arises when multiple mating leads to sperm competition that disadvantages sperm from genetically inferior mates. A reduction in genetic quality is associated with costly selfish genetic elements (SGEs), and studies in invertebrates have shown that males bearing sex ratio distorting SGEs are worse sperm competitors than wild-type males.We used a vertebrate model species to test whether females can avoid an autosomal SGE, the t haplotype, through polyandry. The t haplotype inhouse mice exhibits strong drive in t heterozygous males by affecting spermatogenesis and is associated with homozygous in utero lethality. We used controlled matings to test the effect of the t haplotype on sperm competitiveness. Regardless of mating order, t heterozygous males sired only 11% of zygotes when competing against wild-type males, suggesting a very strong effect of the t haplotype on sperm quality. We provide, to our knowledge,the first substantial evidence that polyandry ameliorates the harmful effects of an autosomal SGE arising through genetic incompatibility. We discuss potential mechanisms in our study species and the broader implications for the benefits of polyandry.
雌性多次交配（一妻多夫制）在许多动物类群中广泛存在，间接遗传益处是有利于一妻多夫制的主要进化力量。当多次交配导致精子竞争，使来自遗传上较差配偶的精子处于劣势时，就会产生一妻多夫制的诱因。遗传质量的下降与代价高昂的自私遗传元件（SGEs）有关，对无脊椎动物的研究表明，携带扭曲性别比例的SGEs的雄性在精子竞争中比野生型雄性更差。我们使用一种脊椎动物模式物种来测试雌性是否可以通过一妻多夫制避免常染色体SGE——t单倍型。家鼠中的t单倍型通过影响精子发生在t杂合雄性中表现出强烈的驱动力，并与子宫内纯合致死率有关。我们使用控制交配来测试t单倍型对精子竞争力的影响。无论交配顺序如何，t杂合雄性与野生型雄性竞争时仅产生了11%的受精卵，这表明t单倍型对精子质量有非常强烈的影响。据我们所知，我们提供了首个实质性证据，证明一妻多夫制可改善因遗传不兼容而产生的常染色体SGE的有害影响。我们讨论了我们研究物种中的潜在机制以及一妻多夫制益处的更广泛含义。
