Multispecies interactions: causes and effects of species fluctuations in space and time

多物种相互作用：物种时空波动的原因和影响

• 批准号: RGPIN-2016-05621
• 负责人: Gilbert, Benjamin
• 金额: $ 2.33万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=709783
• 关键词: Multispecies; interactions; causes; effects; species

One of the most perplexing challenges to understanding biodiversity lies in determining the importance of fluctuations in species abundances through time and space. Scientists have shown that species-specific fluctuations are necessary to maintain diversity, yet fluctuations are known to contribute to species extinctions. Moreover, most species occur in spatially patchy habitats, which are prone to large fluctuations. Reconciling the opposing consequences of fluctuations requires identifying processes that drive fluctuations, determining when and how these processes dominate ecological dynamics, and understanding why different processes lead to divergent outcomes. In this proposal, my lab will test the prevalence and consequences two poorly-understood sources of fluctuations that are common in patchy habitats. The first, ecological drift, is the process of random change in communities that results from demographic stochasticity, and how this stochasticity is dampened or propagated through ecological interactions. There have been several calls for formalizing drift as a fundamental process in ecology. Our research test the importance of drift in competitive communities, and identify the conditions in which drift overwhelms deterministic processes. This will be complemented by parallel research on drift in food webs, with a focus on how stochasticity scales across trophic levels. Both empirical studies will be used to inform theoretical models that will formalize the importance of habitat patch size, species interactions, among-species differences in demographic stochasticity, and body size on ecological drift. The second part of the proposed research will test the prevalence and effects of fluctuations that result from dynamic feedbacks between local interactions and dispersal. These feedbacks are poorly understood for most systems, yet structure diversity within patches and across landscapes. Importantly, local interactions and dispersal are dependent on temperature, providing a unique opportunity to understand their dynamic feedbacks but also making this understanding imperative for conservation. We will use a specialist plant-herbivore system that is naturally fragmented to estimate the temperature-dependence of herbivore feeding rates, dispersal rates and impacts on plants, and resulting changes in plant patchiness and local abundances of herbivore species. We will use these parameters to predict how chronic temperature change and fluctuating temperatures alter dynamic feedbacks between local interactions and dispersal, and test these predictions using observational studies and large-scale experimental metacommunities. Overall, these studies of causes and consequences of species fluctuations will address fundamental gaps in understanding how biodiversity is maintained, and provide new insights for conservation in an era of global change.

理解生物多样性最令人困惑的挑战之一在于确定物种丰度在时间和空间上波动的重要性。科学家们已经证明，物种特有的波动是保持多样性所必需的，但已知波动有助于物种灭绝。此外，大多数物种出现在空间分布不均匀的生境中，容易出现大的波动。研究波动的相反后果需要确定驱动波动的过程，确定这些过程何时以及如何主导生态动态，并理解为什么不同的过程导致不同的结果。 在这项提案中，我的实验室将测试在斑块栖息地中常见的两种不太了解的波动来源的流行程度和后果。第一，生态漂移，是随机变化的过程中的社区，结果从人口统计的随机性，以及这种随机性是如何抑制或通过生态相互作用传播。有几个要求正式漂流作为一个基本的生态过程。我们的研究测试漂移在竞争社区的重要性，并确定漂移干扰确定性过程的条件。这将通过对食物网漂移的平行研究来补充，重点是随机性如何在营养水平上扩展。这两个实证研究将被用来通知理论模型，将正式的栖息地斑块大小，物种间的相互作用，在人口统计随机性，和身体大小对生态漂移的物种差异的重要性。 拟议研究的第二部分将测试当地相互作用和扩散之间的动态反馈所产生的波动的普遍性和影响。对于大多数系统，这些反馈知之甚少，但斑块内和景观间的结构多样性。重要的是，当地的相互作用和传播依赖于温度，提供了一个独特的机会，了解他们的动态反馈，但也使这种理解保护势在必行。我们将使用一个专业的植物-草食动物系统，该系统是自然分散的，以估计草食动物的摄食率，扩散率和对植物的影响的温度依赖性，以及由此产生的植物斑块和草食动物物种的本地丰度的变化。我们将使用这些参数来预测慢性温度变化和温度波动如何改变局部相互作用和扩散之间的动态反馈，并使用观测研究和大规模实验亚稳态来测试这些预测。 总体而言，这些对物种波动原因和后果的研究将解决在理解生物多样性如何维持方面的根本差距，并为全球变化时代的保护提供新的见解。