BACKGROUND AND AIMS The observed positive diversity effect on ecosystem functioning has been scarcely assessed in terms of intraspecific trait variability within populations. Intraspecific phenotypic variability could stem both from underlying genetic diversity and plasticity in response to environmental cues. The latter might derive from modifications on plant's epigenome and potentially last multiple generations in response to previous environmental conditions. We disentangled experimentally the role of genetic diversity and diversity of parental environments on population productivity, resistance against environmental fluctuations and intraspecific phenotypic variation. METHODS A greenhouse-experiment was conducted where different types of populations of Arabidopsis thaliana were established: one population type with differing levels of genetic diversity and another type, genetically identical, but with varying diversity levels of parental environments (parents grown in same or different environments). The latter population type was further combined, or not, with experimental demethylation to reduce the potential epigenetic diversity produced by the diversity of parental environments. Further, all populations were each grown under different environmental conditions (control, fertilization and waterlogging). Mortality, productivity and trait variability were measured in each population. KEY RESULTS Parental environments triggered phenotypic modifications on the offspring, which translated into more functionally diverse populations when offspring from parents grown under different conditions were brought together in mixtures. In general, the increase of neither genetic diversity nor diversity of parental environments had a remarkable effect on productivity or resistance against environmental fluctuations. However, when the epigenetic variation was reduced via demethylation, mixtures were less productive than monocultures (i.e. negative net diversity effect), caused by the reduction of phenotypic differences between different parental origins. CONCLUSIONS Diversity of environmental parental origins within a population could ameliorate the negative effect of competition between coexisting individuals by increasing intraspecific phenotypic variation. Diversity of parental environments could thus have comparable effects to genetic diversity. Disentangling the effect of genetic and diversity of parental environments appears as an important step in understanding the effect of intraspecific trait variability on coexistence and ecosystem functioning.

中文翻译：

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亲本环境的多样性比遗传多样性更能增加拟南芥种群的表型变异，但同样会影响生产力

背景和目的 观察到的对生态系统功能的积极多样性影响几乎没有根据种群内的种内性状变异性进行评估。种内表型变异可能源于潜在的遗传多样性和对环境线索的可塑性。后者可能源自对植物表观基因组的修改，并可能持续多代以响应先前的环境条件。我们通过实验解开了遗传多样性和亲本环境多样性对种群生产力、对环境波动的抵抗力和种内表型变异的作用。方法进行了温室实验，其中建立了不同类型的拟南芥种群：一种具有不同遗传多样性水平的种群类型和另一种具有遗传相同但亲本环境多样性水平不同的类型（亲本生长在相同或不同的环境中）。后一种种群类型进一步结合或不结合实验性去甲基化，以减少亲本环境多样性产生的潜在表观遗传多样性。此外，所有种群均在不同的环境条件（对照、施肥和涝渍）下生长。测量了每个种群的死亡率、生产力和性状变异性。主要结果 亲代环境触发了后代的表型改变，当在不同条件下生长的亲代的后代混合在一起时，表型改变会转化为功能更加多样化的种群。一般来说，遗传多样性和亲本环境多样性的增加都对生产力或对环境波动的抵抗力没有显着影响。然而，当表观遗传变异通过去甲基化减少时，由于不同亲本来源之间表型差异的减少，混合物的生产力低于单一栽培（即负净多样性效应）。结论 种群内环境亲本起源的多样性可以通过增加种内表型变异来改善共存个体之间竞争的负面影响。因此，父母环境的多样性可能对遗传多样性产生类似的影响。