The limits of evolutionary adaptation in ecological time: experimental evolution and ecology.

我的研究项目使用实验室实验来研究生态学和进化的基本过程。单细胞酵母和藻类的种群很容易在实验室中维持，并且由于它们非常大的规模（在一个小烧瓶中有数十亿个个体）和快速的周转（几小时的生成时间），它们使实时研究大规模过程成为可能。我将使用这些实验室的微观模型来研究三种过程。第一个项目通过展示不同的生活方式如何在短时间内进化来探索适应的极限。我将追踪一系列的变化，使藻类通过光合作用在光中生长（像绿色植物）进化成可以在完全黑暗中生长的类型，使用有机化学物质作为食物来源（像真菌）。第二个项目研究适应的特殊性。不同种类的细菌或酵母菌各自可以代谢一定范围的底物，就像动物只消耗有限范围的食物一样。我将记录酵母群体的饮食如何进化，当他们提供了一个复杂的底物混合物，如他们在自然环境中遇到。这些实验的目的是表明，可以从涉及代谢途径结构的生化原理来预测实验室人群中饮食专业化的程度。第三个项目将实验方法扩展到整个社区，以发现他们如何应对严重的压力。这介绍了两种新技术。第一种是带扩散的梯度选择，它通过对不断增加的压力水平的连续适应，使一个具有抵抗力的群落逐渐出现。第二种是蓄积式生物反应器，其设计目的是在自然群落中发现非常罕见的类型，这些类型能够执行某些特定的任务，例如降解特定的毒素。这些技术既可以应用于群落聚集的基本过程，也可以应用于诸如污染土壤和水的生物修复等实际问题。

My research program uses laboratory experiments to investigate fundamental processes in ecology and evolution. Populations of unicellular yeasts and algae are easily maintained in the laboratory, and by virtue of their very large size (billions of individuals in a small flask) and rapid turnover (generation times of a few hours) they make it possible to study large-scale processes in real time. I shall use these laboratory microcosms to study three kinds of process. The first project explores the limits of adaptation by showing how radically different ways of life can evolve within short periods of time. I shall trace the series of modifications that enable an alga that grows in the light by photosynthesis (like a green plant) to evolve into types that can grow in complete darkness, using an organic chemical as a food source (like a fungus). The second project investigates the specificity of adaptation. Different strains of bacteria or yeast can each metabolize a certain range of substrates, just as animals consume only a limited range of foodstuffs. I will document how diet of yeast populations evolves when they are offered a complex mixture of substrates, such as they encounter in natural environments. The goal of these experiments is to show that the degree of dietary specialization that evolves in laboratory populations can be predicted from biochemical principles involving the structure of metabolic pathways. The third project extends the experimental approach to whole communities to discover how they can respond to severe stress. This introduces two novel techniques. The first is gradient selection with dispersal, which contrives the gradual emergence of a resistant community by successive adaptation to increasing levels of stress. The second is the accumulating bioreactor, which is designed to discover very rare types in natural communities that are capable of performing some defined task, such as degrading a particular toxin. These techniques can be applied both to fundamental processes of community assembly and to practical problems such as the bioremediation of polluted soil and water.