The ecology and evolution of biodiversity in natural metacommunities

社区生态学研究的一个基本目标是了解生物多样性在空间和时间上是如何维持的。在21世纪初，社区生态学被批评为缺乏机械力量，过于偶然。作为回应，现代群落生态学强调两种方法：（1）旨在确定生态过程的机械实验，而不是从描述性模式中推断它们，（2）认识到群落通过分散而形成区域网络或“元生态性”，提供了一个一般的预测框架来理解生态结果。然而，实验测试的metacquitality理论在实际的自然metacquitities是非常稀缺的困难，在现场操作的扩散，从而提出了一个最大的知识差距今天面临的生态学。我的实验室研究北方加州一年生草原植物的生态学和生物多样性的进化。一年生植物是理想的，以测试metacromitality过程中的领域，个人和整个社区可以通过种子，模拟扩散转移。在这个系统中，我已经表明，有限的扩散阻止物种访问合适的栖息地补丁，并在空间尺度上的扩散限制体现是由环境结构。然而，我们不知道这个结果随着时间的推移有多稳定，也不知道它对社区/元生态城市尺度上的多样性有多稳定。我们将使用操纵性现场实验来测试以下预测，这些预测构成了三个研究目标的基础：1.扩散导致物种观察到的占有模式与预期的模式不匹配，如果物种被完美地分类到环境梯度的适当部分，（允许测试哪里和为什么发生失配）2.分散是非随机的，基于种子传播媒介（例如，动物，水文学）连接栖息地斑块，影响群落丰富度和组成3.由于扩散导致种间竞争者在某些栖息地斑块中重叠，而不是其他斑块，因此扩散历史指导竞争相互作用和持久性的演变。所提出的目标弥合了后居生态学，进化生态学和景观生态学之间的根本差距，测试了后居预测的现实可行性，推进基本理论。然后，基本理论可以为保护行动提供信息（例如，应在什么样的空间尺度上管理景观以保护区域进程？），在我的研究系统和其他系统中，如加拿大森林，那里的生态动态观察较慢（例如，世代时间长）或多样性不易操纵。最终，我们将提供新的证据，说明生态过程如何以及为什么在自然系统中跨尺度相互作用，推动生物多样性的进化和尺度依赖性。

A fundamental goal motivating community ecology research is to understand how biodiversity is maintained in space and time. In the early 2000s, community ecology was criticized as lacking mechanistic power and being too wrought with contingency. In response, modern community ecology emphasizes two approaches: (1) mechanistic experiments designed to pinpoint ecological processes, rather than infer them from descriptive patterns, and (2) recognizing that communities are linked by dispersal to form a regional network, or "metacommunity", offering a general predictive framework to understand ecological outcomes. However, experimental tests of metacommunity theory in actual natural metacommunities are exceptionally scarce given the difficulty of manipulating dispersal in the field, thus presenting one of the greatest knowledge gaps facing ecology today. My lab studies the ecology and evolution of biodiversity in a metacommunity of annual grassland plants in Northern California. Annual plants are ideal to test metacommunity processes in the field given that individuals and whole communities can be translocated via seed, simulating dispersal. In this system, I have shown that limited dispersal prevents species from accessing suitable habitat patches, and that the spatial scales at which dispersal limitation manifests is determined by environmental structure. However, we do not know how stable this outcome is through time or its consequences for diversity at community/metacommunity scales. We will use manipulative field experiments to test the following predictions that form the basis of three research objectives: 1.Dispersal causes species' observed occupancy patterns to mismatch patterns that would be expected if species were perfectly sorted into suitable portions of environmental gradients (allowing tests of where and why mismatches occur) 2.Dispersal is non-random, occurring directionally from some patches to others based on how seed dispersal vectors (e.g., animals, hydrology) connect habitat patches, affecting community richness and composition 3.Because dispersal causes interspecific competitors to overlap in some habitat patches and not others, dispersal histories direct the evolution of competitive interactions and persistence The proposed objectives bridge fundamental gaps between metacommunity ecology, evolutionary ecology, and landscape ecology, testing the real-world feasibility of metacommunity predictions, advancing basic theory. Basic theory can then inform conservation action (e.g., at what spatial scale should landscapes be managed to preserve regional processes?), both in my study system and in others, such as Canadian forests, where ecological dynamics are slower to observe (e.g., long generation times) or diversity less amenable to manipulation. Ultimately, we will provide novel evidence of how and why ecological processes interact across scales in natural systems, driving evolution and the scale-dependence of biodiversity.