The Role of Prey Capture Thread in the Origin and Evolution of Spider Orb-webs

[9417803]蜘蛛用圆网捕捉猎物是独一无二的。圆织蜘蛛和它们的网吸引了研究行为、生态学和进化的生物学家的注意，也引起了研究蜘蛛织网所产丝特性的生物化学家和分子生物学家的兴趣。圆网捕获猎物的能力在很大程度上取决于其捕获猎物的丝线的粘性。如果没有这些线，许多触网的昆虫就会在蜘蛛跑过去制服它们之前逃跑。捕获猎物的丝线也有助于吸收猎物撞击网时的冲击力，从而加强网的强度。然而，这些猎物捕获线的特性却很少得到研究。这项研究将检查猎物捕获线特性的变化，并确定它们与蜘蛛圆网的起源、进化和运作之间的关系。最原始的圆网是水平方向的，包含干燥，模糊的捕获线，称为钩线。更高级和更多样化的织球蜘蛛群体会产生垂直定向的网，网中含有粘稠的粘胶捕获线。本研究将测量从较不高度组织的网中捕获的猎物线的粘性、抗拉强度和延伸性，这些网的组织程度低于球网、含钩线的球网和含粘线的球网。该研究将测试以下假设：球网的精确和简约的结构对捕获线的粘性、抗拉强度和可扩展性有很高的要求；这些特征在垂直网中变得更加重要，因为垂直网的方向需要它们吸收更大的力，因为它们可以拦截飞得更快的猎物。它还将显示钩状猎物捕获线的粘性如何与蜘蛛的旋转解剖结构有关，并确定旋转解剖结构的变化是否促进了球形网的起源。从这种比较中获得的信息和见解将回答有关圆网进化的主要问题，更全面地表征蜘蛛丝的功能特性，并促进对蛛网组成、结构和功能的更综合的看法。这些见解可能最终在复合材料和粘合剂或冲击吸收结构的设计中有用。

9417803 Spiders are unique in their use of orb-webs to capture prey. Orb-weaving spiders and their webs have attracted the attention of biologists who study behavior, ecology, and evolution as well as the interest of biochemists and molecular biologists who study the properties of the silk spiders manufacture to build those webs. The ability of an orb-web to capture prey depends in large part on the stickiness of its prey capture threads. Without these threads, many insects that strike a web would escape before a spider could run to and subdue them. Prey capture threads also help absorb the impact of prey that strike a web and, in this way, strengthen the web. The properties of these prey capture threads, however, have received very little study. This research will examine changes in the properties of prey capture threads and determine how they are associated with the origin, evolution, and operation of spider orb-webs. The most primitive orb-webs are horizontally oriented and contained dry, fuzzy capture threads called cribellar thread. More advanced and diverse groups of orb-weaving spiders produce vertically oriented orb-webs that contain viscous adhesive capture threads. This research will measure the stickiness, tensile strength, and extensibility of the prey capture threads from webs that are less highly organized than orb-webs, orb-webs containing cribellar thread, and orb-webs containing adhesive threads. The research will test the hypotheses that the precise and parsimonious architecture of orb-webs places a premium on the stickiness, tensile strength, and extensibility of capture threads; and that these characteristics become even more critical in vertical orb-webs whose orientation requires them to absorb greater forces because they intercept prey that fly faster. It will also show how stickiness of cribellar prey captur e threads is related to a spider's spinning anatomy and determine whether changes in spinning anatomy facilitated the origin of the orb-web. The information and insights gained from this comparison will answer major questions about the evolution of orb-webs, more fully characterize the functional properties of spider silk, and foster a more integrated view of spider web composition, structure, and function. These insights may ultimately be useful in the design of composite materials and adhesive or impact-absorbing structures.