Spatial determinants of food web structure and function, from landscape to global scales

食物网是如何随空间变化的？一方面，由于当地环境的差异或有限的扩散，遥远的食物网可能包含不同的物种。食物网的这种差异可能是极端的，当它们相距如此之远，以至于来自不同的物种库。另一方面，即使物种组成不同，物种的特征可能保持不变，因此食物网以相同的方式“运作”。解决空间对食物网结构和功能的影响，对于了解大规模压力源（如气候变化、森林破碎化）如何影响食物网至关重要。为了解决空间如何影响食物网的问题，我们需要（a）在景观和大陆尺度上重复实验，以确定扩散或地理学如何改变物种或特征;（B）使这种重复的食物网暴露于环境变化，如气候变化和扩散减少，如孤立的森林片段;以及（c）在不同地点之间移植物种甚至食物网，以将物种特征的地点差异与环境分开。在这个建议中，我提出了这样一个研究计划，基于大型无脊椎动物（主要是未成熟的昆虫）在热带凤梨科植物充满水的腋中发现。这些小系统（通常小于1升）可以以高密度出现，因此是热带森林碳预算和生物多样性的重要贡献者。重要的是，凤梨科植物广泛分布于各地和各大洲（北美洲、中美洲和南美洲）。我协调了一个由45名研究人员组成的网络，他们在整个范围内研究这个系统。** 我的研究计划考虑如何气候变化，森林破碎化，分散和物种池影响凤梨食物网的结构和功能在景观到大陆尺度。为了研究气候变化，我们将首先使用海拔作为替代，因为今天的中海拔气候预计将成为未来的高海拔气候。我们还将关注降雨，预计在新热带地区的变化超过温度，及其对凤梨食物网的影响。为了研究碎片化，我们将使用树洞-一个非常类似于凤梨科植物的系统-因为凤梨科植物在我们的碎片中的密度太不均匀了。为了研究扩散，我们将把群体遗传学的方法应用于食物网中的许多物种。为了研究物种库的影响，我们将在哥斯达黎加、波多黎各、法属圭亚那和巴西进行重复实验，并比较11个国家汇编的食物网数据（在这两种情况下都利用研究网络）。最后，我们还将操纵食物网顶部（捕食者）和食物网底部（枯叶）的特征，以帮助理解食物网的功能。总而言之，这项研究提案为理解食物网在景观和全球范围内的功能以及环境变化如何破坏这种功能提供了蓝图。**

How do food webs change over space? One the one hand, distant food webs may contain different species because of differences in the local environment or limited dispersal. Such differences in food webs may be extreme when they are so far apart as to draw from different species pools. On the other hand, even though species composition differs, the traits of the species may remain the same, such that food webs “work” the same way. Resolving the effects of space on the structure and functioning of food webs is critical for understanding how large-scale stressors (e.g. climate change, forest fragmentation) affect food webs. To resolve how space affects food webs, we need to (a) replicate experiments over landscape and continental scales, to determine how dispersal or biogeography changes species or traits; (b) expose such replicated food webs to environmental change, like altered climate, and reduced dispersal, such as occurs in isolated forest fragments; and (c) transplant species or even food webs between sites, to separate site-differences in species traits from the environment.******In this proposal I present such a research program, based on the macroinvertebrates (largely immature insects) found in the water-filled axils of tropical bromeliads. These small systems (typically <1L) can occur at high density and are therefore important contributors to the carbon budget and biodiversity of tropical forests. Importantly for this proposal, bromeliads occur widely across landscapes and continents (North, Central and South America). I co-ordinate a network of 45 researchers who work on this system throughout its range. ******My research program considers how climate change, forest fragmentation, dispersal and the species pool affect the structure and functioning of bromeliad food webs at landscape to continental scales. To study climate change, we will first use elevation as a proxy, as today's mid-elevation climate is expected to be the future's high-elevation climate. We will also focus on rainfall, expected to change more than temperature in the Neotropics, and its impact on bromeliad food webs. To study fragmentation, we will use treeholes - a system very similar to bromeliads – as bromeliad densities in our fragments are too spotty. To study dispersal, we will apply methods from population genetics to many species in the food web. To study effects of the species pool, we will conduct replicated experiments in Costa Rica, Puerto Rico, French Guiana and Brazil and compare compiled food web data over 11 countries (in both cases making use of the research network). Finally, we will also manipulate the traits at the top of food webs (predators) and at the bottom of food webs (dead leaves) to help understand how the food web functions. ******In sum, this research proposal provides a blueprint for understanding how food webs function at landscape and global scales, and how environmental change may disrupt that functioning. **