Ecological and evolutionary dynamics

自然生态系统最显著的特征之一是其物种的巨大多样性。这种多样性可能因地点和时间而异。不太明显但同样引人注目的是进化多样性：表型和基因频率的时间和空间变化。这种变化是如何产生和维持的？这些问题是基本生态和进化研究的根本利益，也是保护生物多样性的基础。在基本层面上，我们知道答案：任何类型的生物体的丰度都取决于它出生、死亡和在不同地点之间移动的速度（在更长的时间尺度上，物种形成等进化力量发挥了作用）。但是，要弄清楚细节是极其困难的，因为出生率、死亡率和运动率在空间和时间上会有很大的差异，并取决于许多因素。我的研究涉及出生，死亡和运动的基本过程如何使用模型系统产生生物多样性模式，在模型系统中可以测量和操纵这些过程的速率。 我的建议描述了三组解决不同问题的项目：（1）人口和环境的随机性如何与确定性力量相互作用，以推动人口和社区动态？我建议用由快速生长的原生生物和细菌组成的实验室微观群落来回答这个问题。这个系统允许我直接操纵人口统计随机性和其他因素的强度，这在大多数其他系统中是不可能的。(2)环境的时间变异能像空间变异那样有效地维持遗传多样性吗？我建议通过测试湖泊细菌对水化学空间和时间变化的局部适应来回答这个问题，使用我开发的一种新协议来移植细菌。(3)物种间的相互作用如何影响当地的适应和物种沿着环境梯度的分布？我建议研究生物环境（邻近植物）如何影响高山植物如何适应其恶劣的非生物环境，从而影响适应性遗传变异的维持沿着海拔梯度和确定物种的海拔范围限制。* *它结合了对经典问题的新方法和对以前没有解决的问题的直接攻击。这些结果将提高我们对随机性的理解，提供关于环境波动是否维持遗传多样性的第一个实地数据，并解决有关范围限制的生态和进化决定因素的公开问题。除了有助于基本的理解，拟议的工作将为7名研究生提供培训，并为至少13名本科生提供研究经验。

One of the most striking features of natural ecosystems is their great diversity of species. This diversity can vary among sites and over time. Less obvious, but equally striking, is evolutionary diversity: temporal and spatial variation in phenotypes and gene frequencies. How is this variation generated and maintained? These questions are of fundamental interest for basic ecological and evolutionary research, and also underpin the conservation of biodiversity. At a basic level, we know the answer: the abundance of any type of organism just depends on the rates at which it gives birth, dies, and moves between sites (and on longer timescales uniquely-evolutionary forces like speciation come into play). But working out the details is extremely difficult, since rates of birth, death, and movement can vary greatly in space and time and depend on many factors.****My research addresses how the fundamental processes of birth, death, and movement generate patterns in biodiversity using model systems in which the rates of these processes can be measured and manipulated.  My proposal describes three sets of projects addressing different questions: (1) How do demographic and environmental stochasticity interact with deterministic forces to drive population and community dynamics? I propose to answer this question with laboratory microcosm communities comprised of fast-growing protists and bacteria. This system allows me to directly manipulate the strength of demographic stochasticity and other factors, manipulations that are impossible in most other systems. (2) Can temporal environmental variation maintain genetic diversity as effectively as spatial variation? I propose to answer this question by testing for local adaptation of lake bacteria to spatial and temporal variation in water chemistry, using a novel protocol I have developed to transplant bacteria in time as well as space. (3) How do species interactions affect local adaptation and species distributions along environmental gradients? I propose to examine how the biotic environment (neighboring plants) affects how alpine plants adapt to their harsh abiotic environment, thereby affecting the maintenance of adaptive genetic variation along elevational gradients and determining species' elevational range limits. ****The proposed research is hypothesis-driven. It combines new approaches to classic problems with direct attacks on problems that have not previously been addressed. The results will improve our understanding of stochasticity, provide the first field data on whether environmental fluctuations maintain genetic diversity, and resolve open questions about the ecological and evolutionary determinants of range limits. Besides contributing to fundamental understanding, the proposed work will provide training for 7 graduate students and provide research experience for at least 13 undergraduates.**