Consensus in cockroach and termite phylogeny illuminates the origins of sociality

Cockroaches and termites (Blattodea) occur in almost all terrestrial ecosystems and include important decomposers, pests, as well as groups of medical importance. However, the evolution and systematics of Blattodea have long remained unresolved and recent phylogenomic studies have recovered divergent results that conflict significantly among each other and with morphology-based phylogenies. Using methods designed to counter common sources of error in genome scale phylogenetic estimation, we re-analyze the deep phylogeny of Blattodea using the largest datasets assembled to date including published transcriptomes, mitochondrial genomes, as well as data derived from Sanger-sequencing. All three datasets recovered a congruent, well-resolved and strongly supported phylogeny of Blattodea with a monophyletic Solumblattodea, and with Nocticolidae + Corydiidae comprising the earliest branching clade. The enigmatic families Lamproblattidae + Anaplectidae comprise a sister clade to Cryptocercidae + Isoptera, a novel result shedding light on the evolution of eusociality in termites. We propose the name Lanablattae for the clade Lamproblattidae + Anaplectidae and Artioblattodea for Xylophagodea + Lanablattae. Ancestral state reconstruction suggests that the ancestors of Artioblattodea was not monogamous, implying that kin selection may only play a major role in the later stages of the evolution of eusociality, while non-nepotistic cooperation may be relatively more important at the onset of social group forming. Our results provide a robust backbone phylogeny of cockroaches and termites, opening new possibilities for studying macroevolutionary patterns in this biodiverse order.

蟑螂和白蚁（直翅目）几乎存在于所有陆地生态系统中，它们不仅是重要的分解者，也是害虫，并且在医学上具有重要地位。然而，直翅目的进化与系统发育问题长期以来一直未得到解决。最近的分子系统发育研究得出了相互冲突的结果，这些结果与基于形态学的系统发育树存在显著差异。通过设计用以抵消基因组规模系统发育估计中常见误差来源的方法，我们重新分析了直翅目的深层次系统发育，使用了迄今为止构建的最大数据集，包括已发表的转录组、线粒体基因组以及来自Sanger测序的数据。这三个数据集均恢复了直翅目的一个一致、清晰且得到强烈支持的系统发育树，其中Solumblattodea为单系群，Nocticolidae + Corydiidae构成最早分支的类群。神秘的家系Lamproblattidae + Anaplectidae与Cryptocercidae + Isoptera构成姐妹群，这一新颖的结果为白蚁的社会性进化提供了新的见解。我们提出将Lamproblattidae + Anaplectidae命名为Lanablattae，将Xylophagodea + Lanablattae命名为Artioblattodea。祖先状态重建表明，Artioblattodea的祖先并非一夫一妻制，这暗示了亲缘选择可能只在社会性进化的后期阶段扮演主要角色，而非亲缘合作可能在社交群体形成初期相对更为重要。我们的研究结果为蟑螂和白蚁提供了一个稳健的系统发育骨架，为研究该生物多样性丰富的目中的宏观进化模式开辟了新的可能性。