Abstract Functional traits have been linked to relevant vital rates across co-occurring species, such as growth and survival. However, the relationship between plant traits and germination has been much less studied, despite that germination can be a key transition for plants. Building on evolutionary theory, we propose that variation in germination fraction across co-occurring desert annual plants may result from the interaction of post-germination plant traits, density dependence and microsite type. Our study system consisted of three summer annual species abundant in a desert in western Argentina, for which we quantified germination fractions in three microsite types: Larrea divaricata shrub, Bulnesia retama shrub, and open spaces among shrubs. Based on post-germination trait data (summarized by a principal component, PC1), the annual species can be arranged in terms of increasing stress-tolerance, from Amaranthus standleyanus, to Gomphrena martiana and Tribulus terrestris. We found an interaction between PC1 and density of conspecific seeds suggesting that the strength of plastic negative density-dependence decreased with the increase of plant stress-tolerance. Our results emphasize that both plastic and non-plastic (bet-hedging) mechanisms would contribute to shape germination dynamics across annual plants, and that plant traits can offer parsimonious explanations for such cross-species variation.

中文翻译：

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性状-密度-微位点相互作用表明共生沙漠一年生植物的塑性和非塑性萌发策略

摘要 功能性状与共生物种的相关生命率有关，例如生长和存活。然而，尽管萌发可能是植物的关键转变，但对植物性状与萌发之间的关系的研究却少得多。基于进化理论，我们提出，共生沙漠一年生植物发芽率的变化可能是发芽后植物性状、密度依赖性和微型场地类型的相互作用造成的。我们的研究系统由阿根廷西部沙漠中丰富的三种夏季一年生物种组成，我们量化了三种微型地点类型的发芽率：Larrea divaricata 灌木、Bulnesia retama 灌木和灌木间的开放空间。基于发芽后性状数据（由主成分 PC1 概括），从 Amaranthus standleyanus 到 Gomphrena martiana 和 Tribulus terrestris，一年生物种可以根据增加的压力耐受性排列。我们发现 PC1 与同种种子密度之间存在相互作用，表明塑性负密度依赖性的强度随着植物胁迫耐受性的增加而降低。我们的结果强调，塑料和非塑料（赌注对冲）机制都有助于塑造一年生植物的发芽动态，并且植物性状可以为这种跨物种变异提供简洁的解释。我们发现 PC1 与同种种子密度之间存在相互作用，表明塑性负密度依赖性的强度随着植物胁迫耐受性的增加而降低。我们的结果强调，塑料和非塑料（赌注对冲）机制都有助于塑造一年生植物的发芽动态，并且植物性状可以为这种跨物种变异提供简洁的解释。我们发现 PC1 与同种种子密度之间存在相互作用，表明塑性负密度依赖性的强度随着植物胁迫耐受性的增加而降低。我们的结果强调，塑料和非塑料（赌注对冲）机制都有助于塑造一年生植物的发芽动态，并且植物性状可以为这种跨物种变异提供简洁的解释。