Am Nat. 2021 Apr;197(4):434-447. doi: 10.1086/713067. Epub 2021 Feb 26.
AbstractAn individual's lifetime fitness and patterns of mating between individuals are interdependent features of sexual organisms. Mating systems (outcrossing vs. selfing or mating between close relatives) can affect the distribution of offspring fitness, which generally declines with inbreeding, which in turn is related to a population's genetically effective size (). Fitness and mating patterns are also expected to vary with proximity of mates (i.e., population density). Consequently, density and may influence demographic and genetic changes over generations and interact in their effects. Here, we report an experiment designed to assess the influence of these two population-level properties on mating system and lifetime fitness. In experimental arrays under quasi-natural conditions, we varied the density and of the hermaphroditic annual legume . We recorded components of fitness for each individual and employed microsatellite markers to estimate outcrossing and assign paternity. We used aster analyses to estimate lifetime fitness for genetic families using female (seeds set) and male (seeds sired) reproduction as fitness measures. With estimates from these analyses, we assessed the evidence for a trade-off between fitness attained through female versus male function, but we found none. Lifetime fitness increased with density, especially under high . Outcrossing rates increased with density under high but declined modestly with density under low . Our results show that density and have strong direct effects on fitness and mating systems, with negative fitness effects of low limiting the positive effects of increasing density. These findings highlight the importance of the interactive effects of density and on lifetime fitness.
摘要个体的终生适应度和个体间的交配模式是有性生物相互依存的特征。交配系统(异交与自交或近亲交配)会影响后代适应度的分布,一般来说,近亲繁殖会导致适应度下降,而这又与种群的有效遗传大小()有关。适应度和交配模式也预计会随着配偶的接近程度(即种群密度)而变化。因此,密度和可能会影响几代人的人口和遗传变化,并相互影响其效果。在这里,我们报告了一项旨在评估这两个种群特征对交配系统和终生适应度的影响的实验。在准自然条件下的实验中,我们改变了雌雄同体的一年生豆科植物的密度和。我们记录了每个个体的适应度组成部分,并使用微卫星标记来估计异交率并确定父本。我们使用星分析来估计遗传家族的终生适应度,以雌性(种子设定)和雄性(种子父本)繁殖作为适应度衡量标准。通过这些分析的估计,我们评估了通过雌性与雄性功能获得的适应度之间是否存在权衡,但我们没有发现这种权衡。终生适应度随密度增加而增加,尤其是在高的情况下。在高的情况下,异交率随密度增加而增加,但在低的情况下,异交率随密度略有下降。我们的结果表明,密度和对适应度和交配系统有强烈的直接影响,低的负面适应度效应限制了密度增加的积极影响。这些发现强调了密度和对终生适应度的交互作用的重要性。