The Ecological and Individual Context of Host Choice and Reproductive Isolation: a Behavioral Approach

了解地球巨大生物多样性的起源是进化生物学家的主要目标。生物多样性有两个主要因素：存在的大量生物物种，以及在不同物种中以不同方式进化的各种特征，以使它们适应特定的生态挑战。近年来，人们认识到，产生性状多样性的同一过程也可能促进物种水平多样性的形成。也就是说，生态适应性分化现在被认为促进了物种形成(物种形成)。该项目采用新的方法来评估各种草食性叶甲虫种群(寄主形式)所经历的不同生态挑战如何导致这些种群以较低的速度杂交和交换基因，从而使它们走上物种形成的道路。这些寄主形式一生都生活在一个或另一个树种上。这个项目研究了三种寄主形式：与自然界中特定种类的枫树、赤杨和柳树相关的寄主形式。众所周知，这些寄主形式更喜欢使用它们的本地寄主(例如，对于枫树寄主形式的枫树)，并且在它们上生长和发育得最好。因此，这些寄主形式已经不同地适应了它们各自的寄主植物。该项目提出了三个主要问题：第一，本土寄主植物的相对可用性是否影响其相关寄主形式与其他寄主形式的甲虫交配的频率？也就是说，寄主形式发现自己所处的生态环境的这一方面是否会影响它们分化为独立物种的可能性？其次，在决定两种寄主形式进行或不进行杂交的程度时，哪些特定的生殖障碍是最重要的？不同的寄主形式是在不同的时间或在不同的植物上交配，还是它们无法在替代寄主上生存，因此它们之间根本不会发生交配？第三，每个寄主的平均倾向在多大程度上掩盖了个体甲虫在行为上的重要差异，这些差异决定了哪种寄主植物更受欢迎，以及外国配偶是否被接受？这些问题中的每一个都涉及关键的未决问题，即生态因素如何以及在多大程度上有助于物种形成和生物多样性的生产。这项研究的一部分将与范德比尔特大学的一门讲座相结合，本科生将收集和分析与课堂主题相关的数据。本科生还将通过参加专门的研究课程来更积极地参与。过去，在这个实验室进行研究的学生中，有一半以上是女性。通过研究生态环境变化对栖息地利用和种群间杂交的影响，该项目将促进对人类对生物所经历的生态环境的广泛影响如何影响生物多样性的理解。通过评估决定寄主植物选择的行为，这项工作将帮助我们了解促进采用新寄主植物的因素，例如农业害虫。

Understanding the origins of the Earths tremendous biodiversity is a major goal of evolutionary biologists. Biodiversity has two major elements: the great number of species of organisms that exist, and the great variety of traits that have divergently evolved in different species to adapt them to their particular ecological challenges. In recent years, it has become appreciated that the same process that yields diversity in traits may also promote the formation of species-level diversity. That is, ecologically adaptive divergence is now believed to promote species formation (speciation). This project adopts novel approaches to evaluate how it is that the different ecological challenges experienced by various herbivorous leaf beetle populations (host forms) can cause those populations to interbreed and exchange genes at a reduced rate, thus setting them on the path to speciation. These host forms live their entire lives on one or another tree species. This project studies three host forms: those associated with specific species of maple, alder, and willow trees in nature. These host forms are known to prefer to use their native hosts (e.g., maple, for the maple host form) and to grow and develop best on them. These host forms have thus divergently adapted to their respective host plants. The project asks three major questions: First, does the relative availability of a native host plant influence the frequency with which its associated host form mates with beetles of other host forms? That is, does this aspect of the ecological context in which host forms find themselves influence the likelihood that they will diverge into separate species? Second, what particular reproductive barriers are most important in determining the degree to which two host forms do or do not interbreed? Do different host forms mate at different times or on different plants, or do they fail to survive on alternative hosts so that no mating between them occurs at all? Third, to what degree do the average tendencies of each host form mask biologically important variation among individual beetles in the behaviors that determine which host plant is preferred and whether or not a foreign mate is accepted? Each of these questions gets at critical outstanding issues about how and to what degree ecological factors contribute to the process of speciation and the production of biodiversity. Part of this research will be integrated with a lecture course at Vanderbilt University, with undergraduates collecting and analyzing data that is relevant to the topics being covered in class. Undergraduates will also more actively participate through enrollment in dedicated research courses. In the past, more than half of the students who have conducted research in this lab have been women. By examining the consequences of changing ecological context for habitat use and interbreeding between populations, this project will promote understanding of how widespread human impact on the ecological context experienced by organisms may affect biodiversity. By evaluating the behaviors that determine host plant selection, this work will help us to understand factors that promote the adoption of new host plants, as in the case of agricultural pests.