Department of Biology and Integrated Bioscience Program, University of Akron, Akron, Ohio, USA.
Sci Rep. 2012;2:833. doi: 10.1038/srep00833. Epub 2012 Nov 12.
Correlated evolution of traits can act synergistically to facilitate organism function. But, what happens when constraints exist on the evolvability of some traits, but not others? The orb web was a key innovation in the origin of >12,000 species of spiders. Orb evolution hinged upon the origin of novel spinning behaviors and innovations in silk material properties. In particular, a new major ampullate spidroin protein (MaSp2) increased silk extensibility and toughness, playing a critical role in how orb webs stop flying insects. Here, we show convergence between pseudo-orb-weaving Fecenia and true orb spiders. As in the origin of true orbs, Fecenia dragline silk improved significantly compared to relatives. But, Fecenia silk lacks the high compliance and extensibility found in true orb spiders, likely due in part to the absence of MaSp2. Our results suggest how constraints limit convergent evolution and provide insight into the evolution of nature's toughest fibers.
特征的相关性进化可以协同作用，促进生物功能。但是，如果某些特征的可进化性受到限制，而其他特征不受限制，会发生什么呢？球形网是 12000 多种蜘蛛起源的关键创新。球形网的进化取决于新型纺丝行为的起源和丝材料特性的创新。特别是，一种新的主要膨体蛛丝蛋白（MaSp2）增加了丝的延展性和韧性，在球形网如何阻止飞行昆虫方面发挥了关键作用。在这里，我们展示了伪球形织网蜘蛛 Fecenia 与真正的球形蜘蛛之间的趋同进化。与真正的球形蜘蛛的起源一样，Fecenia 的牵引丝与近亲相比有了显著的改善。但是，Fecenia 的丝缺乏在真正的球形蜘蛛中发现的高顺应性和延展性，这可能部分是由于 MaSp2 的缺失。我们的结果表明了约束如何限制趋同进化，并为研究自然界最坚韧的纤维的进化提供了线索。
