Collaborative Research: Antarctic Dry Valley Nematode Communities: Establishment, Function, and Response to Disturbance

线虫是一种微小的蛔虫，是能够在南极干谷土壤中生存的最复杂的动物之一。如果线虫向栖息地的扩散是均匀的，并且受地理限制是不受限制的，那么线虫群落就有可能在南极洲干谷的所有土壤中建立起来，就像它们在其他研究过的生态系统中所做的那样。线虫在干谷的分布是不完整的。因此，线虫的扩散率很低，或者线虫群落的建立是由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决定的。生境适宜性可由碳可利用性或盐度等因素来确定。本研究项目围绕从个体到生态系统尺度的中心假设进行组织，以了解线虫如何在南极干谷土壤中分散、生存和发展功能群落。假设：(1)干旱对线虫群落功能的影响大于温度；(2)生境适宜性是决定干谷线虫群落建立和维持的主要因素，而非扩散。为了验证这些假设，将进行实地工作，通过从各种地点取样，包括广泛的盐度、湿度和碳含量，来检查似乎适合线虫群落生长和建立的栖息地的特征。稳定同位素研究（C和N）将提供关于进入土壤生态系统和支持线虫的C来源的信息。将在野外用诱捕器和实验室用分子技术检查扩散情况，以调查具有相似形态特征的广泛分布的线虫之间存在的遗传变异。线虫的生存策略将在野外和实验室条件下进行研究，以更好地了解这些动物如何能够在恶劣的气候条件下生存。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、资源配置主要投资于生存的生态系统中。关于这种变化的影响程度的任何知识，以及各种土壤物理和化学特性的影响，最终都可以外推到其他环境。

9522665 Virginia 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.