DISSERTATION RESEARCH: Adaptive Radiation and Interspecific Gene Flow in High Andean Espeletiinae: A Coalescent Approach

9623696 Schaal由该奖项资助的研究探索适应性辐射的工作原理，这是促进生物多样性的基本进化过程之一。适应性辐射在物种群中是明显的，这些物种从它们起源于单一的共同祖先开始，经历了异常的、往往是迅速的多样化。在植物中，这种现象在高海拔的热带生境中最为明显。在南美洲北部的安第斯山脉，星科植物（Espeletiinae）亚族已经分化成80多个物种和一系列壮观的形态形式，使其成为适应性辐射的经典例子和研究植物进化的重要模式系统。这一类群的一个有趣的特征是，在同一栖息地内，几个高度互育的埃斯波提亚科物种同时出现的频率很高。这就提出了本奖项要解决的主要问题：这些物种杂交的频率有多高？杂交在这一群体的适应性辐射中发挥了什么作用？杂交有可能将适应性基因从一个物种传播到另一个物种，甚至导致新物种的迅速产生，这使得这些问题特别令人着迷。在该奖项的支持下，将从这些共存物种的许多个体中收集基因样本。通过DNA测序检测到的这些个体和物种之间的差异，将使用由聚结理论的最新理论进展提供的强大的统计框架进行分析，使测试物种之间遗传交换的证据成为可能。研究结果将为水化作用的基本问题提供答案，不仅是在speletiinae的适应性辐射中，而且在所有水化作用可能在进化中发挥重要作用的植物中。研究结果将增强我们对热带生物多样性的认识，并有助于制定特有植物物种的保护策略。

9623696 Schaal Research funded by this award probes the workings of adaptive radiation, one of the fundamental evolutionary processes that foster biodiversity. Adaptive radiation is manifest in groups of species which, from their origins in a single common ancestor, have experienced exceptional and often rapid diversification. In plants, this phenomenon is most apparent within high elevation tropical habitats. In the Andes mountains of northern South America, the subtribe Espeletiinae (Asteraceae) has diversified into over 80 species and a spectacular array of morphological forms, making it a classic example of adaptive radiation and an important model system for studying evolution in plants. One of the many interesting characteristics of this group is the high frequency with which several highly inter-fertile species of Espeletiinae co-occur within the same habitats. This raises the main questions addressed in this award: how often do such species hybridize, and what role has hybridization played in the adaptive radiation of this group? The potential for hybridization to spread adaptive genes from one species to another and even result in the instant creation of new species makes these questions particularly fascinating. With support from this award, genetic samples will be collected from many individuals of these co-occurring species. Variation among these individuals and species, detected by DNA sequencing, will be analyzed using the statistically powerful framework provided by recent theoretical advances in coalescent theory, making it possible to test for evidence of genetic exchange among species. Results will provide answers to basic questions about the role of hydridization, not just in the adaptive radiation of the Espeletiinae but it all plants where hydridization may play an important role in evolution. Findings will enhance our knowledge of tropical biodiversity and aid in conservation strategies for endemic plant species.