1. Intraspecific diversity of dominant species in native plant communities can modulate ecosystem function under both optimal and stressful conditions. Yet, few genotype by environment interaction studies quantify differences in the shape of plasticity functions or phenotypic breakpoints across genotypes in natural populations.
2. Using three genotypes with a history of drought selection, we performed a greenhouse study on the dominant tallgrass prairie species Andropogon gerardii. We investigated phenotypic plasticity and recovery differences among genotypes across a water availability gradient, measuring growth‐related, instantaneous and cumulative phenotypes. To further understand genotype by environment effects, we quantified plasticity functions and breakpoints among genotypes.
3. Like other studies, we found strong evidence for phenotypic and plasticity differences among genotypes. However, we also found nonlinear plasticity functions and breakpoints were common across phenotypes, especially relative growth rates, biomass allocation and root architecture. Drought selected genotypes were also more likely to flower during recovery, but all genotypes were resilient to drought across treatments.
4. We demonstrate that plasticity functions may help explain intraspecific diversity, patterns of selection and nonlinear community responses to more variable rainfall within an experimental population. In particular, plasticity functions can help disentangle drought/variability tolerance versus acquisitive strategies. A better understanding of intraspecific diversity in this grass species will provide more mechanistic insight into its ability to buffer ecosystem changes and provide resiliency in the tallgrass prairie under future droughts.

中文翻译：

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非线性干旱可塑性揭示了优势草种的种内多样性

1. 原生植物群落中优势种的种内多样性可以在最佳和胁迫条件下调节生态系统功能。然而，很少有基因型通过环境相互作用研究来量化自然种群中各个基因型在可塑性功能或表型断点形状上的差异。
2. 我们使用了三种具有干旱选择历史的基因型，对占主导地位的高草草原种Andropogon gerardii进行了温室研究。我们调查了整个水利用梯度中各基因型之间的表型可塑性和回收率差异，测量了与生长相关的，瞬时的和累积的表型。为了进一步了解环境影响的基因型，我们对基因型之间的可塑性函数和断点进行了量化。
3. 与其他研究一样，我们发现了基因型之间表型和可塑性差异的有力证据。然而，我们还发现非线性可塑性函数和断点在表型之间是常见的，尤其是相对生长速率，生物量分配和根系结构。干旱选择的基因型也更有可能在恢复过程中开花，但所有基因型在处理过程中均能抵抗干旱。
4. 我们证明可塑性函数可能有助于解释种内多样性，选择模式和对实验种群内更多变化的降雨的非线性群落反应。尤其是，可塑性函数可以帮助克服干旱/变异性容忍性与获得性策略的区别。更好地了解该草种的种内多样性将提供更多的机械洞察力，以了解其在未来干旱下在高草草原中缓冲生态系统变化并提供韧性的能力。