Priority Effects and Nonhierarchical Competition Shape Species Composition in a Complex Grassland Community.
Priority Effects and Nonhierarchical Competition Shape Species Composition in a Complex Grassland Community.
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DOI：
10.1086/701434
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发表时间：
2019-03
期刊：
影响因子：
--
通讯作者：
Mordecai EA
中科院分区：
文献类型：
--
作者：
Uricchio LH;Daws SC;Spear ER;Mordecai EA
利基和适应度差异控制着竞争的结果，但确定它们在被入侵社区中的相对重要性（可能远未达到平衡）仍然是一个紧迫的问题。此外，目前尚不清楚主要针对相互作用物种对而开发的研究竞争的经典方法是否能够充分捕捉复杂物种组合中的动态。我们使用来自草原群落的两种本地物种和三种外来物种的竞争实验来参数化种群动态模型。我们发现了本地物种之间最小的适应度差异或生态位差异的证据，导致缓慢的替代动态和优先效应，但巨大的适应度优势允许外来物种无条件入侵本地物种。外来物种之间强烈的种间竞争驱动的优先效应在 80% 的模型结果中推动了两个外来物种之一的单物种优势，而在其余 20% 的模型结果中则出现了本地和外来物种之间的非等级竞争和共存的复杂混合。真菌感染是一种普遍假设的共存机制，其适应度效应较弱，不太可能对共存产生实质性影响。与之前关于主要以本地为主的群落中的成对结果的研究相比，我们的工作支持近中性动态和优先效应作为入侵群落物种组成驱动因素的作用。
Niche and fitness differences control the outcome of competition, but determining their relative importance in invaded communities—which may be far from equilibrium—remains a pressing concern. Moreover, it is unclear whether classic approaches for studying competition, which were developed predominantly for pairs of interacting species, will fully capture dynamics in complex species assemblages. We parameterized a population-dynamic model using competition experiments of two native and three exotic species from a grassland community. We found evidence for minimal fitness differences or niche differences between the native species, leading to slow replacement dynamics and priority effects, but large fitness advantages allowed exotics to unconditionally invade natives. Priority effects driven by strong interspecific competition between exotic species drove single-species dominance by one of two exotic species in 80% of model outcomes, while a complex mixture of nonhierarchical competition and coexistence between native and exotic species occurred in the remaining 20%. Fungal infection, a commonly hypothesized coexistence mechanism, had weak fitness effects and is unlikely to substantially affect coexistence. In contrast to previous work on pairwise outcomes in largely native-dominated communities, our work supports a role for nearly neutral dynamics and priority effects as drivers of species composition in invaded communities.
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