DISSERTATION RESEARCH: Phylogenesis of Hostshifts and Specialization in Neodiprion Sawflies

哈佛大学的Brian Farrell博士和Catherine Linnen女士获得了一笔赠款，用于研究新物种产生的生态和地理环境。特别是，进化生物学家长期以来一直在争论物种形成是否需要地理上的繁殖障碍。现在有令人信服的证据表明，在以植物为食的昆虫中，当个体转移到新的寄主植物时，在没有繁殖的地理障碍(即共生)的情况下，可能会出现新的物种。但这种物种形成模式在产生植物食性昆虫惊人多样性方面所起的作用仍未得到检验，因为大多数研究都集中在单一分叉或最近分叉的物种上。这项研究的目的是了解不同物种形成模式对当代多样性的贡献，并确定某些生活史属性(例如，草食和饮食专业化)是否使生物体倾向于特定的物种形成模式。这些问题将在锯蝇属Neodiprion(膜翅目：Diprionidae)中解决，这是一组北美针叶树食性昆虫，包括几种害虫。具体地说，这项研究将通过检测DNA序列和形态特征的种间差异来阐明Neodiprion属物种之间的进化关系。这项研究的结果将为基本的生物学问题提供重要的见解：新物种是如何以及为什么形成的？此外，这项研究将有助于我们了解Neodiprion的本地和入侵物种，并可能揭示该属内神秘的、寄主专化的物种。这些研究完成后，将通过万维网向公众提供一个数据库，其中包括博物馆标本、出版物、生活史信息、地理范围和每一种新蚊虫的数字图像。

A grant has been awarded to Dr. Brian Farrell and Ms. Catherine Linnen at Harvard University to investigate the ecological and geographical circumstances under which new species arise. In particular, evolutionary biologists have long debated whether geographic barriers to reproduction are required for species formation. There is now convincing evidence that in plant-feeding insects, new species can arise in the absence of geographical barriers to reproduction (i.e., in sympatry) when individuals shift to a new host plant. But the role that this speciation mode has played in generating the staggering diversity of plant-feeding insects remains untested, as most studies have focused on single diverging or recently diverged species. The goal of this research is to understand the contribution that different speciation modes have made to contemporary diversity and to determine whether certain life history attributes (e.g., herbivory and dietary specialization) predispose organisms to particular speciation modes. These questions will be addressed in the sawfly genus Neodiprion (Hymenoptera: Diprionidae), a group of North American conifer-feeding insects that includes several pest species. Specifically, this study will elucidate the evolutionary relationships between species in the genus Neodiprion by examining interspecific variation in DNA sequences and morphological characteristics.The results of this study will provide important insights into the fundamental biological question: How and why do new species form? In addition, this research will contribute to our understanding of native and invasive species of Neodiprion and may uncover cryptic, host-specialized species within the genus. Upon completion of these studies, a database including museum specimens, publications, life history information, geographic range, and digital images for each Neodiprion species will be made publicly available via the World Wide Web.