Data from: The battle of the sexes over seed size: support for both kinship genomic imprinting and interlocus contest evolution

utcrossing creates a venue for parental conflict. When one sex provides parental care to offspring fertilized by several partners, the nonproviding sex is under selection to maximally exploit the caring sex. The caring sex may counteradapt, and a coevolutionary arms race ensues. Genetic models of this conflict include the kinship theory of genomic imprinting (parent-of-origin-specific expression of maternal-care effectors) and interlocus conflict evolution (interaction between male selfish signals and female abatement). Predictions were tested by measuring the sizes of seeds produced by within-population crosses (diallel design) and between-population crosses in outcrossing and selfing populations of Arabidopsis lyrata. Within-population diallel crosses revealed substantial maternal variance in seed size in most populations. The comparison of between- and within-population crosses showed that seeds were larger when pollen came from another outcrossing population than when pollen came from a selfing or the same population, supporting interlocus contest evolution between male selfish genes and female recognition genes. Evidence for kinship genomic imprinting came from complementary trait means of seed size in reciprocal between-population crosses independent of whether populations were predominantly selfing or outcrossing. Hence, both kinship genomic imprinting and interlocus contest are supported in outcrossing Arabidopsis, whereas only kinship genomic imprinting is important in selfing populations.

异交（outcrossing）为亲本冲突（parental conflict）构建了发生场景。当某一性别的个体为多个伴侣受精产生的后代提供亲本抚育时，未提供抚育的性别会受到选择压力，以最大化利用提供抚育的性别。提供抚育的性别可能会演化出反适应策略，进而引发协同进化军备竞赛（coevolutionary arms race）。这类冲突的遗传模型包括基因组印记（genomic imprinting）的亲缘理论——即母本护理效应因子（maternal-care effectors）的亲本起源特异性表达，以及基因座间冲突进化（interlocus conflict evolution，即雄性自私信号与雌性抑制之间的相互作用）。本研究通过对异叶拟南芥（Arabidopsis lyrata）的异交和自交种群开展群体内杂交（采用双列杂交设计（diallel design））与群体间杂交，对上述理论预测进行了验证。群体内双列杂交结果显示，多数种群的种子大小存在显著的母本方差（maternal variance）。群体间杂交与群体内杂交的对比分析表明：当花粉来源于其他异交种群时，所结种子的尺寸显著大于花粉来自自交种群或同一种群时的种子尺寸，这一结果支持雄性自私基因与雌性识别基因之间存在基因座间竞争进化（interlocus contest evolution）。亲缘基因组印记（kinship genomic imprinting）的相关证据来自正反交群体间杂交中种子大小的互补性状均值，且该结果与种群主要为异交还是自交无关。综上，在异交的异叶拟南芥中，亲缘基因组印记和基因座间竞争进化均得到了实验支持；而在自交种群中，仅亲缘基因组印记发挥关键作用。