Evolution of Life Cycles and Host Associations and the Historical Biogeography of Aphids (Subfamily Aphidinae)

蚜虫是一种以植物汁液为唯一食物来源的昆虫。由于它们的进食方式，蚜虫有久坐不动的生活方式，并且经常建立非常大的种群。蚜虫科的许多蚜虫专门以重要的农作物和园艺植物为食（例如，许多谷物作物和果树）。因此，一些蚜虫构成了重要的农业害虫，其中一些具有相当的破坏性。一些物种还进化出复杂的生命周期，包括在不相关的植物宿主之间（例如，在果树和谷物之间）进行几代克隆的强制性季节性迁徙。在北半球，蚜虫的种类也非常丰富，2500种蚜虫中只有约1%原产于南半球。然而，关于这个群体的生物多样性、生物地理学和寄主植物进化的几个令人信服的问题仍然没有答案，因为组成物种之间的关系——可以用来解决这些问题——还没有得到很好的理解。该项目旨在启动蚜虫科蚜虫之间的关系研究，以回答以下问题：尽管它们在北半球具有很高的生物多样性，但蚜虫科是否起源于南半球？寄主与植物的关系是如何随时间变化的？这些变化是如何影响物种多样性的？复杂的生命周期是否在蚜虫科的历史中多次出现？我们将从外部形态特征和基因序列中收集数据来重建蚜虫科物种之间的关系。该项目将资助一名研究生一年，并将在美国、加拿大、新西兰、中国、阿根廷和欧洲的科学家之间建立国际合作。加深对蚜虫形态的了解可能有助于未来的分类方案。对蚜虫科亲缘关系的进一步了解也有助于今后的生物防治工作，为选择适当的生物防治剂提供信息。

Aphids are insects that tap plant sap as a sole food source. As a consequence of their feeding mode, aphids have sedentary life styles and often build up very large populations. Many aphids in the lineage Aphidinae have specialized in feeding on plant hosts that are important agricultural crops and horticultural species (e.g., many grain crops and fruit trees). Thus, several Aphidinae constitute significant agricultural pests, some quite devastating. Some species also have evolved complicated life cycles that incorporate obligate, seasonal migrations between unrelated plant hosts (for example, between a fruit tree and a grain) over several clonal generations. Aphidinae are also exceptionally species-rich in the northern hemisphere, with only ~1% of the 2500 species native to the southern hemisphere. Several compelling questions concerning the biodiversity, biogeography, and host-plant evolution in this group remain unanswered, however, because relationships among the component species-which could be used to address these questions-are not well understood. This project aims to initiate the study of relationships among Aphidinae aphids, in order to answer questions such as: despite their high biodiversity in the northern hemisphere, did Aphidinae originate in the southern hemisphere? How have host-plant relationships changed through time, and how have these shifts impacted species diversifications? Have complicated life cycles originated multiple times in Aphidinae history? We will collect data from external morphological features and from gene sequences to reconstruct relationships among Aphidinae species. This project will support a graduate student for one year, and will build international collaborations between scientists in the U.S, Canada, New Zealand, China, Argentina, and Europe. Increased insights into morphology of aphids may help in future classification schemes. An improved understanding of Aphidinae relationships may also assist with future biocontrol efforts, informing the selection of appropriate biocontrol agents.