CAREER: Water-Soluble Block Ionomer Complexes

9421025只雀斑线虫是微小的蛔虫，是能够在南极干燥山谷的土壤中生存的最复杂的动物之一。如果线虫在栖息地的扩散是均匀的，不受地理限制，线虫群落可能会在南极洲干燥山谷的所有土壤中建立，就像它们在其他研究的生态系统中所做的那样。干旱河谷线虫分布呈斑块状。因此，线虫群落的建立取决于潜在栖息地的适宜性和线虫在恶劣环境条件下生存的能力。栖息地的适宜性可由碳可获得性或盐度等因素来定义。这项研究项目围绕着从个体到生态系统规模的中心假设来组织，以了解线虫如何在南极干旱河谷土壤中分散、生存和发展功能群落。这些假设是：(1)干燥比温度对线虫群落功能的影响更大；(2)生境适宜性而不是扩散是决定干旱河谷线虫群落建立和维持的主要因素。为了验证这些假设，将进行实地工作，通过从各种地点采样，检查似乎适合线虫群落生长和建立的栖息地的特征，包括广泛的盐度、水分和碳含量。稳定同位素研究(碳和氮)将提供有关进入土壤生态系统和支持线虫的碳源的信息。将在野外用诱捕器检测扩散情况，在实验室用分子技术研究分布广泛、形态特征相似的线虫之间存在的遗传变异性。线虫的生存策略将在野外和实验室条件下进行检查，以更好地了解这些动物如何能够在恶劣的气候条件下坚持下去。此外，土壤食物网是环境变化的敏感指标，特别是在生物多样性低、资源分配主要投资于生存的生态系统中。任何关于这种变化的影响程度的知识，以及各种物理和化学土壤特性的影响，最终都可以推断到其他环境。

9421025 Freckman Nematodes, microscopic roundworms, are among the most complex animals capable of survival in the soils of the Antarctic Dry Valleys. If dispersal of nematodes to habitats is uniform and unlimited by geographical constraints, communities of nematodes could potentially establish in all soils of the Dry Valleys of Antarctica, as they do in other ecosystems studied. Nematode distribution in the Dry Valleys is patchy. It follows that dispersal rates are low, or the establishment of nematode communities is governed by the suitability of potential habitats and the ability of nematodes to survive harsh environmental conditions. Habitat suitability may be defined by such factors as carbon availability or salinity. This research project is organized around central hypotheses that move from individual to ecosystem scales in order to understand how nematodes disperse, survive, and develop functional communities in Antarctic Dry Valley soils. The hypotheses are: (1) nematode community function is more influenced by desiccation than temperature, and (2) habitat suitability, not dispersal, is the major factor determining establishment and maintenance of nematode communities in the Dry Valleys. To test these hypotheses, field work will be conducted to examine the characteristics of habitats that appear suitable for nematode community growth and establishment by sampling from a variety of sites, encompassing a wide range of salinities, moistures, and carbon contents. Stable isotope studies (C and N) will provide information on sources of C entering soil ecosystems and supporting nematodes. Dispersal will be examined with traps in the field, and molecular techniques in the laboratory to investigate the genetic variability that exists between widely distributed nematodes with similar morphological characteristics. The survival strategies of nematodes will be examined under field and laboratory conditions to better understand how these animals are able to persist under harsh climatic conditions. In addition, the soil food web serves as a sensitive indicator of environmental change, particularly in this ecosystem, where biodiversity is low and resource allocation is primarily invested in survival. Any knowledge about the degree of influence of such change, as well as the influence of various physical and chemical soil characteristics, can ultimately extrapolated to other environments.