Linking intra-specific trait variation and plant function: seed size mediates performance tradeoffs within species
Linking intra-specific trait variation and plant function: seed size mediates performance tradeoffs within species
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DOI：
10.1111/oik.06494
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发表时间：
2019-12-01
期刊：
影响因子：
3.4
通讯作者：
Rogers, Haldre S.
中科院分区：
文献类型：
--
作者：
Fricke, Evan C.;Tewksbury, Joshua J.;Rogers, Haldre S.
植物群落内存在大量的种内性状变异，理论上这种变异可能会影响群落的动态。虽然最近的研究集中在性状本身的种内变异，但正是这种变异对植物表现的影响使种内性状变异与种内或种间的生态动态有关。要评估种内性状变异对群落动态的重要性，关键是要了解性状与绩效变异之间的联系，以及性状在调节绩效多个组成部分之间的关系中所起的作用。种子大小被认为影响植物表现的方方面面，包括繁殖力、幼苗生长、传播和对天敌的耐受性。对于两个热带树种，我们评估了种子大小如何与每个物种内的表现差异有关，并确定了种内性状差异是否中介了种内表现的权衡。我们使用田间种子雨收集来表征扩散的大小依赖结果，在靠近或远离同种植物的土壤中播种已知大小的种子以表征对土壤病原体的敏感性，并监测已知大小种子的幼苗生长。我们发现，种内种子大小的差异导致了种内表现的差异。基于性状的表现变异程度始终小于性状变异程度，种子大小对每个物种的表现成分有不同的影响。其中一个物种表现出一种权衡，其中小种子具有繁殖力优势(单位生殖质量的幼苗更多)，但产生更小的幼苗，而另一个物种表现出权衡，即小种子分散到同种密度较低的地区，但对密度敏感的天敌的耐受性较差。我们的结果表明，一个单一的性状可以影响性能的多个组成部分，并可以在共生物种中调节不同的权衡。单一性状在多维生态位空间中的复杂和异质性效应可能有利于种间生态位的分化和共存。
Substantial intra-specific trait variation exists within plant communities, and in theory this variation could influence community dynamics. Although recent research has focused on intra-specific variation in traits themselves, it is the influence of this variation on plant performance that makes intra-specific trait variation relevant to ecological dynamics within or among species. Understanding the links between trait and performance variation, and the role of traits in mediating relationships among multiple components of performance, is critical for assessing the importance of intra-specific trait variation for community dynamics. Seed size is thought to affect aspects of plant performance including fecundity, seedling growth, dispersal and tolerance of natural enemies. For two tropical tree species, we assessed how seed size was related to performance variation within each species and determined whether intra-specific trait variation mediates intra-specific performance tradeoffs. We used field seed rain collection to characterize size-dependent outcomes of dispersal, sowed seeds of known size in soil collected near or far from conspecifics to characterize susceptibility to soil pathogens, and monitored growth of seedlings from seeds of known size. We found that intra-specific seed size variation caused intra-specific performance variation. The degree of trait-based performance variation was consistently smaller than the degree of trait variation, and seed size influenced different components of performance for each species. One species exhibited a tradeoff in which small seeds had a fecundity advantage (more seedlings per unit reproductive mass) but produced smaller seedlings, whereas the other species exhibited a tradeoff in which small seeds dispersed to areas of low conspecific density but were less tolerant of density-responsive natural enemies. Our results indicate that a single trait can influence multiple components of performance and can mediate different tradeoffs in co-occurring species. Complex and heterogeneous effects of a single trait in multidimensional niche space may favour inter-specific niche differentiation and coexistence.