Fungal symbiont effects on dune plant diversity depend on precipitation

1. Historically, mutualisms have been considered to be less important than antagonisms in affecting the composition of ecological communities. In plant communities, beneficial microbes may feature as keystone mutualists in structuring community composition. Understanding the direction and magnitude of mutualist effects at the community scale may be critical for making accurate predictions on plant responses to climate change, particularly for mutualists that ameliorate climate-induced stressors. Such mitigation could shift outcomes between mutualist-enhanced species diversity and mutualist-reduced diversity, depending on whether a mutualist accelerates habitat modification or competitive exclusion by its partner species. 2. Here, we tested the relative importance and interactive effects of altered precipitation and symbiosis between an epichloid fungal endophyte and a dominant grass species for dune plant communities along the Great Lakes, USA. In 2010, we imposed field manipulations of...

1. 长期以来，学界普遍认为互利共生（mutualisms）在影响生态群落组成方面的重要性不及拮抗作用（antagonisms）。在植物群落中，有益微生物可作为构建群落组成的关键互利共生者（keystone mutualists）发挥作用。明晰群落尺度下互利共生者效应的方向与强度，对于精准预测植物对气候变化的响应至关重要，尤其是对于能够缓解气候诱导胁迫因子（climate-induced stressors）的互利共生者而言。这类缓解效应可能会改变两种结果的走向——互利共生者提升物种多样性，或是降低物种多样性，这取决于互利共生者是否会加速其宿主物种的生境改造或竞争排除（competitive exclusion）。
2. 本研究针对美国五大湖沿岸的沙丘植物群落，探究了降水改变与香柱菌属真菌内生菌（epichloid fungal endophyte）-优势草本物种共生关系二者的相对重要性及交互效应。2010年，我们开展了野外操控实验……