Interactions between neighboring plants are critical for biodiversity maintenance in plant populations and communities. Intraspecific trait variation and genome duplication are common in plant species and can drive eco-evolutionary dynamics through genotype-mediated plant–plant interactions. However, few studies have examined how species-wide intraspecific variation may alter interactions between neighboring plants. We investigate how subspecies and ploidy variation in a genetically diverse species, big sagebrush (Artemisia tridentata), can alter the demographic outcomes of plant interactions. Using a replicated, long-term common garden experiment that represents range-wide diversity of A. tridentata, we ask how intraspecific variation, environment, and stand age mediate neighbor effects on plant growth and survival. Spatially explicit models revealed that ploidy variation and subspecies identity can mediate plant–plant interactions but that the effect size varied in time and across experimental sites. We found that demographic impacts of neighbor effects were strongest during early stages of stand development and in sites with greater growth rates. Within subspecies, tetraploid populations showed greater tolerance to neighbor crowding compared to their diploid variants. Our findings provide evidence that intraspecific variation related to genome size and subspecies identity impacts spatial demography in a genetically diverse plant species. Accounting for intraspecific variation in studies of conspecific density dependence will improve our understanding of how local populations will respond to novel genotypes and biotic interaction regimes. As introduction of novel genotypes into local populations becomes more common, quantifying demographic processes in genetically diverse populations will help predict long-term consequences of plant–plant interactions.

中文翻译：

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种内变异介导遗传多样性植物物种的密度依赖性

相邻植物之间的相互作用对于植物种群和群落的生物多样性维护至关重要。种内性状变异和基因组重复在植物物种中很常见，并且可以通过基因型介导的植物 - 植物相互作用来驱动生态进化动力学。然而，很少有研究检查物种范围内的种内变异如何改变相邻植物之间的相互作用。我们研究了具有遗传多样性的物种大山艾树 ( Artemisia tridentata ) 的亚种和倍性变异如何改变植物相互作用的人口统计结果。使用代表A. tridentata范围广泛多样性的重复的、长期的普通花园实验，我们询问种内变异、环境和林龄如何介导邻居对植物生长和存活的影响。空间显式模型显示倍性变异和亚种同一性可以调节植物-植物相互作用，但影响大小随时间和实验地点而异。我们发现，在林分开发的早期阶段和增长率较高的地点，邻居效应的人口影响最为强烈。在亚种内，与二倍体变体相比，四倍体种群对邻居拥挤表现出更大的耐受性。我们的研究结果提供证据表明，与基因组大小和亚种身份相关的种内变异会影响遗传多样性植物物种的空间人口学。在同种密度依赖性研究中考虑种内变异将提高我们对当地人口如何响应新基因型和生物相互作用机制的理解。随着将新基因型引入当地种群变得越来越普遍，量化遗传多样性种群的人口统计过程将有助于预测植物-植物相互作用的长期后果。