Collaborative Research: Higher order interactions, functional trait changes, and species coexistence in an annual plant community

自然群落通常由几十个或几百个相互作用的物种组成。然而，为了简单起见，生态学中物种相互作用的研究通常集中在物种对之间的相互作用上。生态学家通常认为，我们对物种对之间相互作用的理解可以用来理解整个群落的动态。这一核心假设受到了高阶相互作用（HOIs）的潜在挑战，当一对物种之间的相互作用因第三种物种的存在而改变时，就会发生高阶相互作用。hoi可以使物种更容易或更难以在一个多样化的群落中共存，这取决于影响的强度和性质。因此，这些相互作用的可能存在从根本上挑战了我们对如何在自然群落中维持生物多样性的理解。然而，我们对高指向性在自然界中有多强或多普遍知之甚少。该研究将量化草地植物群落中hoi的强度和流行程度，并测试植物物种的某些物理或生理特征是否更容易发生hoi。该项目将解决社区生态学的一个基本挑战，培养一名研究生和博士后研究员，并用于改进高中、本科和研究生水平的课程。该研究将结合大规模的田间实验、植物功能性状的详细测量和数学理论的应用，提出三个问题：(1)自然界中竞争对手之间的高阶相互作用（HOIs）有多强？(2) hoi如何影响物种共存的机会？(3)生态学家能否利用植物功能性状的知识预测自然界中这些相互作用的程度？该项目将通过在加利福尼亚一年生植物群落进行的大型野外实验，量化近150个三方hoi的大小，该实验将焦点物种同时置于两种不同竞争物种的密度变化中。然后，具有hoi的模型将与所收集的人口统计数据相拟合。为了解决拟合HOI的共存后果，将在包含或排除这些HOI项的参数化模型中评估共存的入侵条件和物种持续时间。为了评估hoi的可预测性，该研究将测量植物功能性状对其他竞争对手密度的可塑性响应，并将这些信息用于预测拟合的hoi值。总的来说，这项研究将使生态学家能够量化hoi对物种共存的重要性，并确定其功能基础，为进一步研究这些相互作用的机制奠定基础。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Natural communities are often composed of dozens or hundreds of interacting species. However, for simplicity, the study of species interactions in ecology most often focuses on interactions between pairs of species. Ecologists often then assume that our understanding of interactions between species pairs can be used to make sense of the dynamics of entire communities. This core assumption is challenged by the potential for Higher Order Interactions (HOIs), which occur when the interaction between a pair of species is changed by the presence of a third species. HOIs can either make it easier or more difficult for species to coexist in a diverse community, depending on the strength and the nature of the effects. The possible existence of these interactions therefore fundamentally challenges our understanding of how biodiversity is maintained in natural communities. However, we know very little about how strong or widespread HOIs might be in nature. The research will quantify the strength and prevalence of HOIs among plant species in a grassland community and test if certain physical or physiological characteristics of plant species make HOIs more likely to occur. The project will address a fundamental challenge in community ecology, train a graduate student and postdoctoral researcher, and be used to improve courses offered at the high school, undergraduate and graduate level. The research will combine large-scale field experiments, detailed measurements of plant functional traits, and the application of mathematical theory to ask three questions: (1) How strong are Higher Order Interactions (HOIs) among competitors in nature? (2) How do HOIs affect opportunities for species coexistence? (3) Can ecologists predict the magnitude of these interactions in nature with knowledge of plant functional traits? The project will quantify the magnitude of nearly 150 three-way HOIs through a large field experiment in a California annual plant community subjecting focal species to simultaneously varying densities of two different competitor species. Models with HOIs will then be fit to the demographic data collected. To address the coexistence consequences of the fitted HOIs, the invasion condition for coexistence and species persistence times will be evaluated in parameterized models that either include or exclude these HOI terms. To assess the predictability of HOIs, the research will measure how plant functional traits plastically respond to the densities of other competitors, and this information will be used to predict the value of the fitted HOIs. Taken together, the research will allow ecologists to both quantify the importance of HOIs for species coexistence and identify their functional basis, laying the groundwork for further mechanistic studies of these interactions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.