啮总目昆虫的线粒体基因组多样性及系统发育研究进展

啮总目包括啮虫目（皮虱和书虱）和虱目（羽虱和吸虱），是农业和医学等领域具有重要经济意义和研究价值的类群，目前已鉴定和描述的物种超过10 000个。啮总目昆虫线粒体基因组的变异性在昆虫各类群中最为剧烈，这些变异包括基因组的结构、基因排序、基因含量和链上分布等诸多方面。本文全面分析和总结了啮总目昆虫裂化线粒体基因组的进化属性，并结合两侧对称动物线粒体基因组的裂化特征重构了线粒体基因组环裂化的过程。引入“线粒体基因组核型”的概念来描述动物线粒体基因组丰富的变异程度。动物线粒体的染色体有减小的趋势，而线粒体基因组的裂化正是体现这种趋势的一种重要策略。同时，总结和探讨了目前具有争议的啮总目主要类群间的系统发育关系。本综述为啮总目昆虫线粒体基因组学、啮总目系统发生关系以及两侧对称动物线粒体基因组进化模式的研究提供一个新的视角。

Progress in mitochondrial genome diversity and phylogeny of Psocodea

The superorder Psocodea has over 10 000 described species in two orders: Psocoptera (barklice and booklice) and Phthiraptera (chewing lice and sucking lice). Many psocodean insects are important stored product pests, and some are important vectors for human and animal diseases. Recent studies indicate that psocodean insects have the most dramatic variation of mitochondrial (mt) genomes observed in insects, including genome architecture, gene order, gene content and gene strand asymmetry. In this review, we summarized the evolutionary features of the multipartite mt genomes observed in species of the Psocodea and introduced a new concept “mitochondrial genome karyotypes” to describe the complexity of animal mt genome. Furthermore, in combination with fragmented mt genomes of other bilateral animals, we proposed the mechanism to explain how multipartite circular mt genomes are generated. We propose that the selection pressure for compact mt genomes in bilateral animals favors small mt chromosomes when small mt chromosomes co-exist with the typical large mt chromosomes. Thus, small mt chromosomes may have selective advantages over large ones in bilateral animals. Fragmentation of mt genome is likely an important strategy to streamline mt genome. Meanwhile, we also investigated the current controversial views on the phylogenetic relationships among major lineages of the Psocodea. This review will provide new insights into the evolutionary pattern of mt genome of psocodean insects and other bilateral animals, as well as the phylogeny of Psocodea.