DISSERTATION RESEARCH: The functional consequences of antagonism in fungal communities

了解下个世纪地球气候将如何变化，在科学、社会和经济方面都具有重大意义。为了预测未来的气候，科学家们需要了解世界上最小的生物，真菌和细菌，是如何对不断变化的环境条件做出反应的。这些微生物在地球的碳循环中起着至关重要的作用。它们分解死去的植物，将二氧化碳释放回大气中。目前的气候模型假设这种释放速率是由环境条件决定的，如温度、湿度或土壤ph。这些条件的变化预计会“改变”微生物活动的“刻度盘”。如果天气变暖，微生物会释放更多的二氧化碳；如果天气变冷，微生物释放的二氧化碳就会减少。然而，这种假设忽略了大多数微生物的一个关键方面：它们是技艺高超的战士。真菌和细菌释放出数量惊人的化学物质和化合物，旨在杀死它们的同伴微生物，并在它们的领地上定居。然而，这场战争付出了相当大的代价。微生物必须在使用能量进行战斗或使用能量进行生长之间做出选择。在拟议的工作中，研究人员将量化微生物战斗如何影响环境条件下的分解率，帮助了解微生物驱动的二氧化碳释放将在何时何地对不断变化的环境条件做出不可预测的反应。调查人员还将培训一名高中生，并与一家自然历史博物馆开展拓展活动。在先前多样性功能研究的基础上，研究人员将开发一个可推广的模型，以解开拮抗竞争与环境条件作为微生物介导分解率驱动因素的相对重要性。利用收集到的44种木材腐烂真菌的基线性状数据，将选择100个独特的群落，这些群落具有不同水平的战斗能力、平均抗应力能力和物种丰富度（从3到12个独特物种）。这些群落将聚集在现实的微观世界中，并在最佳条件（温暖和潮湿）和压力条件（寒冷和干燥）下孵化。12周后测量木材分解总量。这项研究将使研究人员能够解决三个主要问题：(1)群落水平的分解与利用微生物个体分解率预测的分解是否不同？(2)这些差异是否取决于个体是好斗真菌还是耐应力真菌？(3)应激和最佳环境条件下拮抗相互作用的相对重要性是否不同？这些问题的答案最终将有助于重建现有的气候模型，并更好地预测全球二氧化碳通量将如何随时间变化。

Understanding how the Earth's climate will change over the next century is of enormous scientific, social, and economic importance. In order to make these projections of future climate, scientists will need to understand how the world's smallest organisms, fungi and bacteria, respond to changing environmental conditions. These microbes play a critical role in the Earth's carbon cycle. They decompose dead plant material, releasing carbon dioxide back into the atmosphere. Current climate models assume that the rate of this release is determined by environmental conditions, such as temperature, moisture, or soil pH. Changes in these conditions are expected to "turn the dial" on microbial activity. If it gets warmer, microbes will release more carbon dioxide; if it gets colder, microbes will release less carbon dioxide. Yet this assumption ignores a key aspect of most microbes: they are highly skilled warriors. Fungi and bacteria release an astonishing number of chemicals and compounds intended to kill their fellow microbes and colonize their territory. This warfare, however, comes at a considerable cost. A microbe must choose between using its energy for combat or using its energy for growth. In the proposed work, the researchers will quantify how microbial combat affects decomposition rates across environmental conditions, helping to understand where and when microbially-driven carbon dioxide releases will respond unpredictably to changing environmental conditions. The investigators will also train a high school student and develop outreach activities with a natural history museum. Building on previous diversity-function studies, the researchers will develop a generalizable model to disentangle the relative importance of antagonistic competition versus environmental conditions as drivers of microbial-mediated decomposition rates. Using baseline trait data collected on 44 wood-decay fungi, 100 unique communities will be selected with varying levels of combative ability, average stress-tolerance ability, and species richness (from 3 to 12 unique species). The communities will be assembled in realistic microcosms and incubated under both optimal conditions (warm and wet) and stressful conditions (cold and dry). Total wood decomposition will be measured after 12 weeks. This study will allow the researchers to address three main questions: (1) Does community-level decomposition differ from what is predicted using the microbes' individual decomposition rates? (2) Do these differences depend on whether the individuals are combative fungi or stress-tolerant fungi? and (3) Does the relative importance of antagonistic interactions differ between stressful and optimal environmental conditions? The answers to these questions will ultimately help restructure existing climate models and better project how global carbon dioxide fluxes will change over time.