SG: Ecological insights from range-expanding populations

随着大气和海洋变暖，植物和动物的地理分布正在扩大。例如，招潮蟹最近将其活动范围扩大到了马萨诸塞州科德角的历史界限以北。虽然科学家们已经记录了数千种物种的范围扩张，但一个大问题仍然存在：这些生物对它们在扩大的范围内占据的新栖息地有什么影响？招潮蟹生活在盐沼，这是经济上重要的生态系统，为渔业和旅游业提供燃料。这项研究将集中在招潮蟹将对新扩大范围内的盐沼产生的影响（即，Cape Cod）。该项目的调查结果将向公众公布。除了本科生和研究生外，中学教师和学生将直接参与这项研究。记录在案的招潮蟹（Uca pugnax）的北方扩张是一个特殊的机会，以测试气候驱动的物种引进对生态系统功能的影响。在其原生分布区，U. pugnax影响一系列沼泽功能，包括初级生产，养分循环和食物网。在身体大小方面，招潮蟹遵循伯格曼法则（身体大小与纬度之间的正相关关系），马萨诸塞州的个体几乎是格鲁吉亚个体的两倍。这种地理模式可以告知在气候变化的背景下，个别种群对生态系统功能的相对影响。本研究将检验以下假设：（1）扩大范围种群中的招潮蟹（例如，马萨诸塞州）将有更大的人均影响沼泽功能比那些在历史范围的人口（例如，格鲁吉亚），因为它们的体型较大。（2.）在沼泽规模，范围扩大的螃蟹将有轻微的影响，沼泽功能相对于历史螃蟹，因为这些人口是10倍小于历史范围的人口。将沿着纬度梯度（格鲁吉亚州、弗吉尼亚州、马萨诸塞州）对一系列生态系统过程（例如，初级生产、分解、底栖动物多样性、植物化学计量）。此外，招潮蟹体型大小与生态系统影响相关的目标假设将在一项中型生态系统研究中进行测试。该奖项反映了NSF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。

As the atmosphere and oceans warm, plants and animals are expanding their geographic distributions. For instance, the fiddler crab recently expanded its range north of its historic limit of Cape Cod, Massachusetts. While scientists have documented the range expansion of thousands of species, a big question remains: What is the impact of these organisms on the new habitats they occupy in their expanded ranges? Fiddler crabs live in salt marshes, which are economically important ecosystems that fuel fisheries and tourism. This research will focus on the impact that fiddler crabs will have on salt marshes in the newly expanded range (i.e., north of Cape Cod). Findings from this project will be made available to the public. Middle-school teachers and students in addition to undergraduate and graduate students will be directly involved in this research. The documented northern expansion of fiddler crabs (Uca pugnax) is an exceptional opportunity to test the effects of climate-driven species introductions on ecosystem functioning. In its native range, U. pugnax influences a range of marsh functioning including primary production, nutrient cycling, and food-webs. In terms of body size, fiddler crabs follow Bergmann's Rule (a positive relationship between body size and latitude) with individuals in Massachusetts being almost twice as large as those in Georgia. This biogeographic pattern may inform the relative effect of individual populations on ecosystem function in the context of climate change. The following hypotheses will be tested in this study: (1.) Fiddler crabs in the expanded-range populations (e.g., Massachusetts) will have larger per-capita effects on marsh functioning than those in the historic-range populations (e.g., Georgia) because of their larger size. (2.) At the landscape-scale, range-expanded crabs will have minor effects on marsh functioning relative to historic crabs because these populations are 10x smaller than historic-range populations. These hypotheses will be tested using a combination of field experiments and observational studies along a latitudinal gradient (Georgia, Virginia, Massachusetts) on a suite of ecosystem processes (e.g., primary production, decomposition, benthic animal diversity, plant stoichiometry). In addition, the targeted hypothesis that fiddler crab body size is correlated with ecosystem impacts will be tested in a mesocosm study.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.