基于转录组序列数据的50种长蝽总科昆虫系统发育基因组学研究

Lygaeoidea is among the largest superfamilies of the true bugs (Hemiptera-Heteroptera). Although the species diversity in Lygaeoidea is lower than that in Miroidea, Reduvioidea, and Pentatomoidea, the diversity of habitats in Lygaeoidea is the most prominent among all of the heteropteran superfamilies. The known habitats of Lygaeoidea include sucking the liquid in leaves, seeds, fruits, and nectar of plants, predating some small arthropods and sucking the body fluids, sucking the blood of mammals, and sucking in the dung of mammals. Corresponding to the diversity of habitats, the taxonomic system of Lygaeoidea is also among the most complex ones in Heteroptera. Some cladistic analyses and molecular phylogenetic analyses had been done, and the most recent two of them suggested that the previous Lygaeidae s. lat. is paraphyletic and most subfamilies within it should be elevated to family level. However, the whole phylogenetic scheme is still far from stable, and the positions of some taxa are still in controversy. The applicant and the research group propose to carry out phylogenomic studies of Lygaeoidea based on the sequences data of transcriptomes of 50 species. The main goal is to reconstruct a complete phylogenetic scheme between all families and subfamilies of Lygaeoidea. We have prepared in three aspects and have done some pilot studies. First, we have known how to use each computer program in the pipeline of phylogenomic analyses based on transcriptome data. Second, we have already obtained 5 transcriptomes data of Lygaeoidea. And we still have other 5 samples in RNAlater which have passed the quality control of RNA. These samples are now kept in refrigerator at -80℃. Third, during the last 10 years, we have published several molecular phylogenetic studies at category levels from kingdom to family, and 6 of them are about the phylogeny of true bugs. During this process, we have accumulated experiences in various steps of phylogenetic analyses, have formed clear thinking about the whole scheme of analyses, and have been familiar with the background knowledge about the morphology and fossils of Heteroptera in the evolutionary history at large time scale.

长蝽总科是半翅目异翅亚目（蝽类昆虫）的第4大总科，其栖境和习性多样性在蝽类昆虫的所有总科中非常突出，如取食植物的叶片、种子、果实、花蜜，捕食其它小型节肢动物，吸食哺乳动物的血液，取食草原上的动物粪便等。与之相应的是，其分类系统也比较复杂。虽然已有的形态特征分支分析研究和分子系统发育研究都显示原先的广义长蝽科为并系，其中大多数亚科应该被提升为科，但是在整体系统发育框架以及若干类群的地位问题上仍存较大争议。申请者计划新测序50种长蝽总科昆虫的转录组，建立完整的科间系统发育关系框架，并已从3个方面做了准备。第一，已掌握基于转录组序列数据重建系统发育的完整数据分析流程。第二，已获得长蝽总科中5个物种的转录组数据；另有5个物种的RNA质控合格样品。第三，申请者已发表的高级阶元系统发育研究案例有6项与蝽类昆虫有关，在整体研究思路和蝽类昆虫大时间尺度进化的形态、化石等方面积累了比较丰富的经验和背景知识。

长蝽总科是半翅目异翅亚目（蝽类昆虫）的第4大总科，其栖境和习性多样性在蝽类昆虫的所有总科中非常突出，其食性范围包括植物的叶片、种子、果实、花蜜，也有部分类群捕食其它小型节肢动物，吸食哺乳动物的血液，取食草原上的动物粪便等。与之相应的是，其分类系统也比较复杂。虽然已有的形态特征分支分析研究和分子系统发育研究都显示原先的广义长蝽科为并系，其中大多数亚科应该被提升为科，但是在整体系统发育框架以及若干类群的地位问题上远未明朗。本项研究目前已经新测序52种长蝽总科昆虫的转录组和9种外群昆虫的转录组，并且还生成了100多个长蝽总科物种的低覆盖度基因组数据，初步建立了科间系统发育关系框架，并进行了分歧时间推断。在已发表的阶段性成果部分，本项研究中原创性地提出了以系统发育基因组学研究为纽带，从基因组和转录组数据中挖掘类群特异性的氨基酸特征（衍征），依托系统发育的树形结构，形成层级式的分子衍征体系，用于物种的快速准确鉴定。这一研究结果已经于2016年发表在著名学术期刊Scientific Reports上。