毛蚜亚科系统发育关系重建及其与寄主植物之间演化关系研究

Chaitophorinae is an important subfamily in Aphididae, Hemiptera, because many species are pests of forestry and agriculture. Chaitophorinae is an indispensable part of model on reconstructing phylogeny of aphid, but the species diversity and the plylogeny of the subfamily were not studied in its entirety. Two tribes, Chaitophorini and Siphini belong in this subfamily. They have some special characteristics both in morphology and life cycle. The monophyly of the subfamily is supported by both molecular and morphological data. But only the monophyly of Siphini and the relationship of the genera in this tribe are settled. The relationships between the two tribes and among genera of Chaitophorini are still puzzles. The host plants of two tribes are quite different, as Chaitophorini feeding on ligneous and Siphini feeding on herbaceous plants. Whether the species feeding on crops and herbages are relatively developed ones? This question is still discussed among the aphid researchers. This proposal is to solve these problems in Chaitophorinae by finding and describing the species diversity, reconstructing the phylogenetic trees and revealing the relationships between the Chaitophorinae species and their host plants based on the macroscopical and microcosmic data. The representative species of all the genera and the tribes in the subfamily will be selected as the samples here. There are 9 genes from 3 genomes used as molecular markers, EF-1α, LWO, CD, 18S rDNA from nuclear genome, COI, COII, Cytb from mitochondrial genome and 16S rDNA, gnd from genome of primary bacterial symbiont of aphid. The analysis of combined molecular and morphological characteristics will suggest the phylogenetic relationships in Chaitophorinae. After combined analysis of the total-evidence database, such as host plants, life cycles, fossils, Paleoclimate, Paleogeology, etc., the relationships between Chaitophorinae and its host plants will be revealed in the phylogenetic trees. The results of this proposal will also be valuable in aphid speciation and mechanism research of pests.

毛蚜亚科是半翅目蚜科的重要类群，是经济树木和主要作物的重要害虫，该亚科物种多样性没有系统描述，亚科内部的系统发育关系至今也没有得到诠释；亚科内2个族，毛蚜族和伪毛蚜族分别取食木本植物和草本植物。因此摸清该亚科的物种组成，重建内部的系统发育关系，探讨该亚科物种与其寄主植物之间的演化关系等，对蚜虫物种分化及蚜虫类害虫形成机制研究具有重要意义。本项目将发现并描述我国毛蚜亚科物种多样性；选取该亚科所有族和属的代表物种及多个外群，利用来自细胞核、线粒体和蚜虫内共生菌的3个基因组的9个基因数据，整合蚜虫形态性状和生活习性等全证据，阐明该亚科各类群间的系统发育关系；基于系统关系框架，结合生物地理、地质气候历史等数据整合性研究，解析该类群与其寄主植物之间的演化历史，为探讨植食性昆虫与植物协同进化、物种形成机制、生物地理演化及蚜虫类害虫进化机制等相关领域的后续科学研究提供范例，而且将丰富生物适应进化理论。

毛蚜亚科是半翅目蚜科的重要类群，是经济树木和主要作物的重要害虫，本研究旨在摸清该亚科的物种组成，重建亚科内部的系统发育关系，探讨该亚科物种与其寄主植物之间的演化关系等，对蚜虫物种分化及蚜虫类害虫形成机制研究具有重要意义。通过开展毛蚜亚科物种形态分类与DNA分类研究，构建了毛蚜亚科标本数据库和毛蚜亚科物种数据库。基于获得的该亚科2族8属670个样本的1609条序列，包括蚜虫线粒体基因COI、COII、Cytb和蚜虫初级内共生菌Buchnera的gnd基因，使用4种物种界定方法阈值+NJ、ABGD、GMYC和PTP，开展了毛蚜亚科的DNA分类和DNA条形码鉴定效果分析。研究结果表明在毛蚜亚科内表现出了相对较高的种间遗传距离和相对较低的种内遗传距离，即利用DNA条形码可以有效地区分该亚科物种；COI与COII基因在DNA条形码研究中是更为合适的基因标记；在物种界定方法上，ABGD与GMYC更适合毛蚜亚科研究。在系统发育研究中，选取了毛蚜亚科2族10属52种作为内群及3科3亚科12种作为外群，基于3个线粒体基因（COI、COII、Cytb）、2个核基因（EF-1α、LWO）、1个蚜虫内共生菌Buchnera基因（gnd）和65个形态性状与生物学数据，分别使用最大简约法、最大似然法和贝叶斯法重建了毛蚜亚科的系统发育关系。研究结果支持毛蚜亚科及其毛蚜族与伪毛蚜族2个族的单系性。在重建的毛蚜亚科系统发育关系的基础上，对亚科内各节点的分歧时间进行了估算，依据物种的寄主植物重建了毛蚜亚科寄主植物祖先状态，并对毛蚜亚科与其寄主植物的演化关系进行了探讨。研究结果表明毛蚜亚科的起源时间大约为白垩纪晚期，明确了该亚科的祖先起源于槭属植物。毛蚜族与伪毛蚜族的分化时间分别为古新世早期和晚期；毛蚜族的祖先起源于槭属植物，随后在毛蚜属中发生了多次由杨属至柳属植物的寄主转移和快速分化；伪毛蚜族伴随着禾本科植物的起源由槭属植物转移至禾本科植物进而发生分化。本研究成果将在很大程度上提高毛蚜类物种的鉴定速度与准确性，为探讨植食性昆虫与植物协同进化、物种形成机制、生物地理演化及蚜虫类害虫进化机制等相关领域的后续科学研究提供范例，而且将丰富生物适应进化理论。