Yeast in the Antarctic Dry Valleys: Biological role, distribution, and evolution

南极干旱山谷中的植被：生物学作用、分布和进化南极极地沙漠的土壤群落由极少数特有的细菌、真菌和无脊椎动物组成。丝状和单细胞真菌都已从南极土壤类型的多样性中分离出来，但极地沙漠土壤中似乎只有酵母是特有的。虽然酵母菌在南极土壤中的生态作用尚不明确，但酵母可能是合成土壤无脊椎动物所需甾醇的异养群落中的主要类群。此外，酵母可能参与积累和调动限制生长的营养物质，如进入极地沙漠食物网的磷。这项多学科研究将确定土壤酵母在麦克默多干谷生态系统中所扮演的角色，以便更好地了解极地沙漠和其他极端环境，并为将酵母纳入温带环境的生物地球化学模型提供基础。土壤微生物区系调节着陆地生态系统的大部分过程，如分解、土壤呼吸、对微、宏观养分的吸收和固定、重金属的解毒等，是全球主要的碳汇。温带地区土壤群落的复杂性给研究生态系统功能的生物和非生物参数之间的关系带来了困难，控制土壤微生物区系种群的因素仍然缺乏了解。南极大陆沙漠地区的极端气候和相对简单的群落结构为确定对许多生态系统过程至关重要的土壤有机体之间的相互作用提供了独特的机会。极地荒漠土壤中酵母菌的丰度和分布将与土壤的物理和化学性质相关，这些数据将利用地理信息系统(GIS)进行存储和分析。将在体外探索几个生理参数，为理解这些生物可能发挥的功能作用奠定基础(S)。干谷酵母的进化将通过根据DNA序列确定谷内和谷间种群关联模式来解决。这些实验将为未来的研究奠定坚实的基础，为合作研究提供更多的机会，从中学到大学的学生都将有机会参与这个项目。

0125611ConnellYeasts in the Antarctic Dry Valleys: Biological role, distribution, and evolutionThe soil community of Antarctic polar desert is comprised of few endemic species of bacteria, fungi, and invertebrates. Both filamentous and single cellular fungi have been isolated from a diversity of Antarctic soil types, but only yeast appear to be endemic to the polar desert soils. Although the ecological roles of yeast in Antarctic soils is undefined, yeast may be the principal taxa in the heterotrophic communities that synthesize sterols required by soil invertebrates. In addition, yeast may be involved in accumulating and mobilizing growth limiting nutrients such as phosphorus into the polar desert food web. This multidisciplinary research will characterize the roles soil yeast play in the McMurdo Dry Valley ecosystem in order to better understand polar deserts and other extreme environments, as well as provide a foundation for incorporating yeast into biogeochemical models of temperate environments. Soil microbiota mediate most of the terrestrial ecosystem processes such as decomposition, soil respiration, the uptake and fixation of micro and macro-nutrients, detoxification of heavy metals, and serve as major global carbon sinks. The complexity of soil communities in temperate regions pose difficulties in studying the relationships between biotic and abiotic parameters of ecosystem function and the factors controlling populations of soil microbiota remain poorly understood. The extreme climate and relatively simple community structure of the continental Antarctica desert regions offer a unique opportunity to define interactions between soil organisms that are central to many ecosystems processes. The abundance and distribution of yeast in polar desert soils will be correlated with physical and chemical soil properties and these data will be stored and analyzed using Geographic Information Systems (GIS). Several physiological parameters will be explored in vitro to develop a basis for understanding the functional role(s) these organisms may play. The evolution of Dry Valley yeast will be addressed by determining intra- and inter-valley population relatedness patterns, based on DNA sequence. These experiments will form a strong foundation for future investigations, provide additional opportunities for collaborative research and students from middle school through college will be given the opportunity to participat in this project.