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

了解地球上巨大的生物多样性的起源是进化生物学家的一个主要目标。 生物多样性有两个主要要素：存在的大量生物物种，以及不同物种为适应其特定的生态挑战而进化出的各种各样的特征。 近年来，人们逐渐认识到，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是促进物种形成（物种形成）。该项目采用新的方法来评估各种食草性叶甲种群（宿主形式）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。 这些宿主形式一生都生活在一个或另一个树种上。 本计画研究三种寄主：自然界中与枫树、桤木及杨柳相关的寄主。 已知这些宿主形式更喜欢使用它们的原生宿主（例如，枫树，为枫树主机形式）和生长和发展最好的。因此，这些寄主形式已经分化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，本地宿主植物的相对可用性是否会影响其相关宿主形式与其他宿主形式的甲虫交配的频率？ 也就是说，宿主形式所处的生态环境的这一方面是否会影响它们分化成不同物种的可能性？第二，在决定两种宿主杂交或不杂交的程度时，什么样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，还是它们不能在其他寄主上生存，所以它们之间根本没有交配？第三，在多大程度上，每种寄主形式的平均趋势掩盖了个体甲虫在决定哪种寄主植物是首选以及是否接受外来配偶的行为中的生物学重要变化？这些问题中的每一个都涉及到关键的悬而未决的问题，即生态因素如何以及在多大程度上促进了物种形成和生物多样性的产生。这项研究的一部分将与范德比尔特大学的一门讲座课程相结合，由本科生收集和分析与课堂上所涵盖的主题相关的数据。本科生也将通过专门的研究课程入学更积极地参与。过去，在这个实验室进行研究的学生中有一半以上是女性。通过研究生境使用和种群间杂交的生态环境变化的后果，该项目将促进了解人类对生物体所经历的生态环境的广泛影响可能如何影响生物多样性。 通过评估决定寄主植物选择的行为，这项工作将有助于我们了解促进采用新寄主植物的因素，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.