Reconstructing web evolution and spider diversification in the molecular era
Reconstructing web evolution and spider diversification in the molecular era
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DOI：
10.1073/pnas.0901377106
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发表时间：
2009-03-31
影响因子：
11.1
通讯作者：
Agnarsson, Ingi
中科院分区：
文献类型：
--
作者：
Blackledge, Todd A.;Scharff, Nikolaj;Agnarsson, Ingi
蜘蛛的进化多样化归功于丝绸的惊人创新。蜘蛛在合成许多不同种类的丝方面是独一无二的，并在它们的一生中利用丝发挥各种生态功能，特别是制作捕食网。在这里，我们构建了一个广泛的更高水平的蜘蛛系统发育结合分子数据和传统的形态和行为特征。我们用这个进化史来检验蜘蛛网只进化一次的假设。然后，我们研究蜘蛛多样化与不同的网络架构和丝绸使用的关系。我们发现球网的单一起源得到了强有力的支持，这意味着捕获丝的纺丝发生了重大转变，球网反复丢失或转化。我们发现，放弃昂贵的筛状捕获丝与蜘蛛的两个主要多样化事件相关(1)。用水性丝胶取代筛状丝，可能解释了现代编织圆球蜘蛛(蜘蛛总科)与筛状编织蜘蛛(Deinopoidae)相比具有更大的多样性(2)。在“RTA分支”，这是编织蜘蛛的姐妹群，包含了一半的蜘蛛多样性，90%的物种丰富度与反复失去筛丝和放弃猎物捕获网有关。在两组患者中，伴随着脑脊膜的丢失是从底物限制的网中释放出来的，无论是通过悬浮在空气中的网，还是通过完全放弃网。因此，蜘蛛在丝和网生产方面的这些行为变化，可能在蜘蛛作为昆虫捕食者的戏剧性进化成功和生态优势中发挥了关键作用。
The evolutionary diversification of spiders is attributed to spectacular innovations in silk. Spiders are unique in synthesizing many different kinds of silk, and using silk for a variety of ecological functions throughout their lives, particularly to make prey-catching webs. Here, we construct a broad higher-level phylogeny of spiders combining molecular data with traditional morphological and behavioral characters. We use this phylogeny to test the hypothesis that the spider orb web evolved only once. We then examine spider diversification in relation to different web architectures and silk use. We find strong support for a single origin of orb webs, implying a major shift in the spinning of capture silk and repeated loss or transformation of orb webs. We show that abandonment of costly cribellate capture silk correlates with the 2 major diversification events in spiders (1). Replacement of cribellate silk by aqueous silk glue may explain the greater diversity of modern orb-weaving spiders (Araneoidea) compared with cribellate orb-weaving spiders (Deinopoidea) (2). Within the "RTA clade," which is the sister group to orb-weaving spiders and contains half of all spider diversity, >90% of species richness is associated with repeated loss of cribellate silk and abandonment of prey capture webs. Accompanying cribellum loss in both groups is a release from substrate-constrained webs, whether by aerially suspended webs, or by abandoning webs altogether. These behavioral shifts in silk and web production by spiders thus likely played a key role in the dramatic evolutionary success and ecological dominance of spiders as predators of insects.