The phasmatodean tree of life: resolving evolutionary patterns of diversity and disparity in a mesodiverse insect lineage

竹节虫科（Phasmatodea）是大型陆生草食性节肢动物中的一个中分化谱系，主要分布在热带和亚热带。它们通常在夜间活动，并表现出显着的伪装形式，模仿植物的各个部分，如树枝，树皮和树叶，以欺骗视觉狩猎捕食者。Phasmatodea包括~3100现存描述的物种，并作为一个模型系统来解决进化生物学中的重要问题，如物种形成，无性进化，形态特征的丧失和恢复，以及分支多样化，或者更准确地说，在地理隔离中重复适应辐射。直到最近，竹节虫和叶虫仍然是最后剩下的昆虫目之一，没有一个强有力的更高层次的系统发育假说。我们最新的分子研究的基础上广泛的转录组学和桑格序列数据，现在已经解决了这些昆虫的早期进化和证实的发现，即现存的多样性是一个令人惊讶的最近快速辐射的结果。我们全面的时间校准的系统发育分析是基于从1200多个分类群的最大系统发育覆盖率选择的数据-超过三分之一的已知物种多样性。该树提供了一个进化框架，用于（i）追踪phasmatodeans的全球历史地理学，（ii）评估物种形成和灭绝的速率，（iii）重建祖先特征状态和参与适应性辐射并对多样化产生影响的关键特征的转变。这些特征包括飞行能力和相关结构的存在，如翅膀和单眼，身体大小和形状，跗附着结构和无性繁殖能力。然而，对于一些关键的进化谱系，其中没有转录组学的数据是可用的，我们的分析仍然产生相互矛盾的系统发育假说。然而，强大的进化情景概述的研究问题，只能从一个可靠的遗传学推断。为了实现这一目标，我们将扩大我们的研究，并应用进一步的基因组学方法，这是基于目标富集选定的外显子为200精心挑选的信息物种的棍棒和叶昆虫。该项目旨在显着推进我们对以前被忽视的昆虫群体在空间和时间上的适应性进化枝多样化的理解。

Stick and leaf insects, or Phasmatodea, are a mesodiverse lineage of large terrestrial herbivorous arthropods with predominantly tropical and subtropical distribution. They are usually nocturnal and exhibit remarkable forms of masquerade crypsis, imitating various parts of plants, such as twigs, bark and leaves to deceive visually hunting predators. Phasmatodea comprises ~3100 extant described species and serves as a model system to address important questions in evolutionary biology, such as speciation, evolution of asexuality, loss and regain of morphological traits, and clade diversification or, more precisely, repeated adaptive radiations in geographic isolation. Until recently, stick and leaf insects stood out as one of the last remaining insect orders without a robust higher-level phylogenetic hypothesis. Our latest molecular studies based on extensive transcriptomic and Sanger sequence data have now resolved the early evolution of these insects and corroborate the finding that the extant diversity is the result of a surprisingly recent rapid radiation. Our comprehensive temporally calibrated phylogenetic analysis is based on data selected for maximum phylogenetic coverage from over 1200 taxa – more than one third of the known species diversity. The tree provides the evolutionary framework for (i) tracing the global historical biogeography of phasmatodeans, (ii) assessing rates of speciation and extinction, and (iii) reconstructing ancestral character states and transformations of crucial traits that are involved in adaptive radiations and have an effect on diversification. These traits comprise flight capability and the presence of associated structures such as wings and ocelli, body size and form, tarsal attachment structures and the capacity for asexual reproduction. Yet, for some crucial evolutionary lineages of which no transcriptomic data is available our analyses still produce conflicting phylogenetic hypotheses. However, robust evolutionary scenarios for the outlined research questions can only be inferred from a reliable phylogeny. To reach this goal, we will expand our studies and apply a further phylogenomic approach, which is based on target enrichment of selected exons for 200 carefully chosen informative species of stick and leaf insects. The project is designed to significantly advance our understanding of adaptive clade diversification across space and time in a previously neglected group of insects.