Collaborative Research: Stochasticity and Cryoconite Community Assembly and Function

冰凝石洞是完全包裹在贫瘠的冰川冰中的生命的口袋。当灰尘吹到冰面上融化了一个很小的、基本上孤立的洞，这个洞可以作为自己的小生态系统，这些生命就形成了。这些灰尘中可能含有细菌、藻类或微小动物等微生物。洞内的微生物相互作用，并执行一个更大的生态系统，如森林的典型功能。在极端寒冷的环境中，如南极干谷，冰锥石洞尤其重要，在那里它们起着生命储存库的作用。由于冰凝石洞大多是封闭的，并且可以持续多年，因此可以随着时间的推移对它们进行追踪，以测试有关相互作用的生物群落如何发展成为功能齐全的生态系统的基本科学问题。该项目将对现有的和实验创建的低温孔进行取样，以了解这些生态系统是如何发展的，以及随机过程（如哪些生物先到达那里）在多大程度上影响最终的群落组成和功能。这些结果不仅将提高我们对微生物群落如何聚集和影响微生态系统（如低温孔）功能的理解，而且还将提高我们对群落聚集过程如何影响更大生态系统（如森林）功能的理解。更好地了解群落的建立、发展和对非生物因素的响应对于预测生态对环境变化的响应至关重要。在众多生态系统中，揭示群落聚集、生物多样性和养分循环之间的联系是至关重要的，因为这些是决定生态对环境变化响应的关键因素。低温结晶岩孔的独特性和很大程度上的孤立性提供了一个实验系统，将促进对驱动群落聚集的过程（例如，随机动力学，如扩散限制、组装顺序和生态漂移）的基本理解。该项目将使用实地抽样活动和一些可操作的实验来检验一个将群落和生态系统生态学理论结合起来的假设：随机过程引导微生物群落聚集和影响生物多样性和生态系统过程的区域模式的程度。将对冰冻孔进行采样，以比较水文连接孔和水文隔离孔之间的群落组成、环境因素和生态系统功能。在两个生长季节期间，还将建造和监测新的冰凝石孔，以具体改变其组装顺序和群落大小，从而将独特的操作实验与实地调查相结合，以解决与南极及其他地区相关的问题。扩增子测序、宏基因组学、显微镜、敏感环境化学方法以及光合作用和呼吸测量将用于测试一系列与区域生物多样性模式、环境因子异质性和生态系统过程相关的子假设。

Cryoconite holes are pockets of life completely encased in otherwise barren glacial ice. These pockets of life form when dust blown onto the ice melts a small, largely isolated hole that can function as its own tiny ecosystem. This dust can contain microorganisms such as bacteria, algae, or microscopic animals. The microorganisms within the hole interact and carry out functions typical of a larger ecosystem, such as a forest. Cryoconite holes are especially important in extreme cold environments such as the Antarctic Dry Valleys, where they function as repositories of life. Because cryoconite holes are mostly enclosed and persist for years, they can be tracked over time to test fundamental scientific questions about how communities of interacting organisms develop to become fully functioning ecosystems. This project will sample existing and experimentally created cryoconite holes to understand how these ecosystems develop and to what degree random processes (such as which organisms get there first) affect the final community composition and functioning. The results will not only improve our understanding of how microbial communities assemble and affect the functioning of microecosystems such as cryoconite holes, but also how the processes of community assembly affect functioning of larger ecosystems, such as forests. A better understanding of community establishment, development, and response to abiotic factors are essential to forecasting ecological responses to environmental change.It is essential to unravel the links between community assembly, biodiversity, and nutrient cycling across numerous ecosystems because these are critical factors determining ecological responses to environmental change. The unique, largely isolated nature of cryoconite holes provides an experimental system that will advance fundamental understanding of the processes (e.g., stochastic dynamics such as dispersal limitation, assembly order, and ecological drift) driving community assembly. This project will use a field sampling campaign and a number of manipulative experiments to test a hypothesis that unites theory in community and ecosystem ecology: the degree to which stochastic processes guide microbial community assembly and affects regional patterns in biodiversity and ecosystem processes. Cryoconite holes will be sampled to compare community composition, environmental factors, and ecosystem functioning between hydrologically connected and isolated holes. New cryoconite holes will also be constructed and monitored over the course of two growing seasons to specifically alter assembly order and community size, thereby pairing a unique manipulative experiment with field surveys to address questions with relevance to the Antarctic and beyond. Amplicon sequencing, metagenomics, microscopy, sensitive environmental chemistry methods, and photosynthesis and respiration measurements will be used to test a series of sub-hypotheses that relate stochasticity to patterns in regional biodiversity, heterogeneity in environmental factors, and ecosystem processes.