基于线粒体基因组探讨白垩纪-第三纪事件对长纺蛛多样化的影响

It has been well recognized that angiosperm radiation during the Cretaceous Terrestrial period facilitated the general diversification of holometabolous insects. The contemporaneous boom of fast terrestrial insects provided food resources, accelerating the diversification of agile spiders. The Cretaceous Tertiary Revolution (KTR) may have been the most important event structuring spider evolution and is hypothesized to be responsible for the success of webless hunting within Entelegynae. The Long-Spinnered Bark Spiders family, Hersiliidae, including the arboreal agile and irregular ground sheet genera, is considered as a possible intermediate between Orbiculariae and the RTA (retrolateral tibial apophysis) clade. However, many questions regarding the origin time and region of hersiliids, the direction of diversification of arboreal adaptation, and its evolutionary relationships within Entelegynae still remain unanswered. In this program, co-worked with the taxonomic scientist of Hersiliidae, Dr. Stefan H. Foord, we will first sequence the mitogenomes of 25 species within 16 genera of Hersiliidae using NGS approaches. Phylogenies will be reconstructed using Bayesian inference, maximum likelihood, and maximum parsimony. Ancient regions and characters will be reconstructed based on the phylogenetic trees. Divergence times will be estimated using fossil and biogeographical calibrations. In combination with amber fossils, the distribution of extant taxa, geographical history, and climate data, ENMs (Environmental Niche Models) will be constructed to explore the potential factors impacting the diversification of hersiliids.

白垩纪-第三纪时期，有花植物的适应辐射，促进了完全变态昆虫的多样化。同时，地表昆虫的大爆发（距今125-90 Ma）为蜘蛛提供了丰富的食物资源，推动了游猎蜘蛛的多样化。白垩纪-第三纪事件作为复杂生殖器类蜘蛛从结网到游猎演化的关键因素，造就了当前蜘蛛目中最广的多样化事件（RTA分支多样化）。长纺蛛作为园网类蜘蛛和地表游猎的RTA分支蜘蛛之间的中间过渡类群，既有树栖游猎型又有地表结网型的种类。但是长纺蛛在蜘蛛目的系统地位、起源时间和地点以及演化方向等问题，一直悬而未决。本研究将联合非洲长纺蛛分类学专家Dr. S. H. Foord，首次利用高通量测序手段获得16属25种长纺蛛线粒体基因组数据，结合化石证据和相关地质年代时间节点，构建长纺蛛系统发育关系，重建祖先区域和特征。同时运用生态位模型，探讨长纺蛛多样化的可能进化驱动力, 最终尝试解答白垩纪-第三纪事件是否影响，如何影响长纺蛛多样化？

基于线粒体基因组探讨白垩纪-第三纪事件对长纺蛛多样化的影响，试图验证长纺蛛非洲起源和地表起源假说，探讨全球长纺蛛多样性演化的成因和过程。主要研究内容包括：1）使用线粒体基因组数据推断覆盖所有属的系统发育进化树，重建祖先特征和历史分布区域；验证地表/非洲起源假说；2）以及长纺蛛I,II,IV步足后跗节分节机制的探索（转录组水平）；3）基于全球蜘蛛目骨干生命树的最新成果，为进一步扩大研究样品的数据，探讨区域群落区系的谱系多样性，研究了简化线粒体全基因组数据集方法，以及K-mers based phylogenetic placement方法。研究进展及成果：1）获得了15种覆盖所有长纺蛛已知属代表的线粒体基因组数据，建立了长纺蛛系统发育进化树，完成祖先特征和祖先区域重建； 2）获得了苏门答腊长纺蛛的转录组数据；3）此外，利用甲虫获得了区域甲虫群落的高通量个体DNA条形码数据，并获得高质量线粒体基因组简化多基因子集，提高了phylogenetic placement的可靠性和准确性。关键数据及其科学意义：1）基于蜘蛛目骨干生命树，结合世界蜘蛛名录和GBIF数据，试探性地研究了世界蜘蛛古生物地理的装配过程; 2) 将二代测序数据和线粒体基因组数据（简化多基因子集）结合，实现了对区域群落数据的谱系多样性分析。

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