Roles of substrate, herbivory and competition in the generation of edaphic endemics: Experimental and historical approaches

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。生态专门化是物种适应特定环境的过程，对于理解生物多样性的两个重要驱动因素：物种形成（新物种的进化）和灭绝至关重要。土壤专家，或只出现在特定土壤类型上的物种，对整体生物多样性贡献很大。在加州，露出地表的蛇形土壤（重金属浓度高，必需植物养分浓度低）只占土地的1%，但却包含了该州14%（312个分类群）的植物分类群。对应激基质的适应解释了为什么在这些基质上发现了植物物种，但不能解释为什么这些物种仅限于它们。一种假说认为，对奇怪基质的适应降低了在更典型基质上生存的能力，但许多地貌学专家在种植后可以在普通土壤上生长。因此，与其他物种的相互作用可能会阻止地学专家在更常见的土壤栖息地定居。这项工作的目的是评估土壤成分、食草动物和植物竞争对手的联合选择是否产生了局限于应激基质的物种。土壤特性，在不同基质上的生长，以及与食草动物和植物竞争对手的相互作用将被测量的Streptanthus属的物种，芥菜科的成员。物种之间的进化关系将在分析中得到解释，以深入了解过去的物种形成事件及其与适应蛇形土壤的关系。一些链菊属植物被列为稀有或濒危物种。将建立一个网站，提供有关土壤和这些植物物种生命各个阶段（从种子到果实）的信息。这些资料将有助于土地管理人员调查这些植物的种群。其中一些土壤专家具有独特的特性，例如在叶子中超积累金属的能力，并且已被用于回收金属污染的土壤和植物采矿，因此本研究将更好地为此类生物修复工作提供信息。培训本科生、研究生和技术人员。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). Ecological specialization, the process by which species adapt to a certain environment, has been central to understanding two important drivers of biodiversity: speciation (the evolution of new species) and extinction. Edaphic specialists, or species that only occur on particular soil types, contribute greatly to overall biodiversity. In California, serpentine soil outcrops (with high concentrations of heavy metals and low concentrations of essential plant nutrients) make up only 1% of the land but contain 14% (312 taxa) of the state's plant taxa. Adaptation to stressful substrates explains why plant species are found on these substrates, but does not explain why such species are restricted to them. One hypothesis suggests that adaptation to odd substrates decreases the ability to live on more typical substrates, but many edaphic specialists can grow on common soils when planted. Interactions with other species may thus be preventing edaphic specialists from colonizing more common soil habitats. The goal of the proposed work is to evaluate whether combined selection from soil components, herbivores and plant competitors has generated species limited to stressful substrates. Soil properties, growth on different substrates, and interactions with herbivores and plant competitors will be measured for the species in the genus Streptanthus, members of the mustard family. The evolutionary relationships among the species will be accounted for in the analyses to gain insight into past speciation events and their relationship with adaptation to serpentine soils. Several species of Streptanthus are listed as rare or endangered. A website will be created with information on soils and all stages in the life of these plant species (seeds through fruits). Such information will be useful for land managers in surveying populations of these plants. Some of these soil specialists have unique properties, like the ability to hyperaccumulate metals in their leaves, and have been used to reclaim metal-contaminated soils and for phytomining, thus this research will better inform such bioremediation efforts. Undergraduate, graduate students and technicians will be trained.