Genotypic diversity mitigates negative effects of density on plant performance: a field experiment and life-cycle analysis of common evening primrose Oenothera biennis

1.Genotypic diversity in plant populations is known to enhance plant performance and ecosystem function. Nonetheless, the effect of genotypic diversity has rarely been examined across a population's lifecycle despite the expectation that changing conditions, such as population density, will alter the benefits of diversity. 2.We simultaneously manipulated a component of genotypic diversity (richness, the number of genotypes) and density of common evening primrose Oenothera biennis to address the consequences for herbivory and lifetime fitness in a two-year field experiment that spanned seed germination to life-time fruit production. We genotyped >1100 seedlings with microsatellite DNA markers to determine realized diversity and density in plots sown with O.biennis seeds. Our design achieved quantitative variation in plant density and diversity, with one to 44 individuals established in field plots and two to eight genotypes per polyculture plot (based on microsatellite analysis of ...1. 已知植物种群的基因型多样性（genotypic diversity）可提升植株表现与生态系统功能。尽管学界普遍推测，种群密度等环境条件的变化会改变多样性带来的收益，但迄今极少有研究覆盖种群完整生命周期来探究基因型多样性的效应。 2. 本研究同时操控了基因型多样性的一个维度——即基因型丰富度（richness，指基因型的数量）以及普通月见草（Oenothera biennis）的种群密度，在一项覆盖从种子萌发到终生结籽全过程的两年田间试验中，探究其对植食为害与植株终生适合度的影响。研究利用微卫星DNA标记（microsatellite DNA markers）对1100余株实生苗进行基因分型，以确定播种了O. biennis种子的样地中的实际多样性与种群密度。本实验设计实现了植株密度与多样性的定量梯度变化：田间样地内定植的植株数量为1至44株，混播样地的基因型数量则为2至8种（基于微卫星分析结果……）