The Nutritional Ecology of the Web of Nephila Clavipes

正如人类通常必须在货币预算内生活一样，我们有理由认为其他生物体也必须在能源预算内生活。特别是在资源有限的情况下，尽可能有效地利用资源必须是重要的。与其他效率较低的有机体相比，那些这样做的有机体大概会处于竞争和进化优势。这些想法看似合理，但很难检验。对行为活动进行分类往往是不可能的。例如，一只动物可能同时参与几项活动，包括调节体温、守卫领地边界、寻找配偶和食物。此外，很难确定适当的资源来衡量。目前也不清楚投入精力寻找食物对增长率、成熟时的大小和年龄有何影响。发育速度和途径的差异可能会对物种的进化产生巨大影响，但很少有研究解决导致这种差异的营养原因。编织圆球蜘蛛为研究资源划分和划分转移的发育后果提供了一个很好的模型系统。蜘蛛从蛋白质等生理上重要的化合物中合成蛛网。旋转球网的活动和对球网的营养投资只能用于捕获猎物，在那次觅食回合中，分配给球网的资源不能用于生长或繁殖，所有猎物捕获都发生在球网上；因此，必须在猎物捕获量减少的时期维持球网。我们将研究大型、分布广泛的球状编织蜘蛛NePhila clavipe觅食的营养生态。我们的实验将使用来自3个不同种群的蜘蛛进行核磁共振和气相色谱分析球体化学。这种编织圆球的蜘蛛的生物学将使我们能够清楚地将觅食与其他活动区分开来，并跟踪不同类型或资源如何在觅食和其他活动之间进行划分。我们还将能够确定在限制资源时，需要在觅食和其他活动之间进行权衡的资源。此外，我们还可以量化资源在各种环境条件下对觅食的投资如何影响生长和发育，我们还可以区分由于遗传差异而产生的模式和由于环境差异造成的模式。这项研究将解决大多数经典觅食模型长期持有的假设(觅食投资的变化反映了资源分配的变化，并且觅食效率的提高提高了相对适合度)，它最终将允许量化觅食和生长之间的资源划分，从而能够调查觅食投资的变化和发展计划的变化之间的精确关系。

Just as humans generally have to live within a monetary budget, it is reasonable to assume that other organisms must live within an energy budget. Particularly when resources are limiting, it must be important to utilize resources as efficiently as possible. Those organisms that do so will presumably be at a competitive and evolutionary advantage compared to others who may be less efficient. These ideas seem sensible, but have been difficult to test. It is often not possible to classify behavioral activities. For example, an animal may be simultaneously involved in several activities including thermoregulating, guarding territory boundaries, and seeking a mate as well as food. In addition, it has been difficult to identify the appropriate resources to measure. It is also not clear how investing energy in searching for food affects growth rate, and size and age at maturity. Variation in development rates and pathways can have tremendous impact on the evolution of a species, but few studies have addressed the nutritional causes that contribute to this variation. Orb-weaving spiders provide an excellent model system for the study of resource partitioning and the developmental consequences of shifts in partitioning. Spiders synthesize their web from physiologically important compounds such as proteins. The activity of spinning the orb web and the nutritional investment into the orb can serve no other purpose than prey capture, the resources allocated to the orb web are unavailable for growth or reproduction during that foraging bout, and all prey capture occurs on the orb web; thus, the web must be maintained through periods of reduced prey capture. We will examine the nutritional ecology of foraging in the large, widely distributed, orb-weaving spider Nephila clavipes. Our experiments will involve NMR and gas chromatographic analysis of orb chemistry using spiders from 3 separate populations. The biology of this orb-weaving spider will allow us to clearly distinguish foraging from other activities and to track how different types or resources partitioned between foraging and other activities. We will also be able to identify resources that, when limiting, necessitate trade-offs between foraging and other activities. In addition, we can quantify how the investment of resources into foraging affects growth and development under a variety of environmental conditions, and we can distinguish patterns that are due to genetic differences from those due to environmental differences. This study will address the long-held assumptions of most classical foraging models (that shifts in foraging investment reflect shifts in resource partitioning and that increased foraging efficiency increases relative fitness) and it will finally allow quantification of resource partitioning between foraging and growth, permitting investigation of the precise relationships between variation in foraging investment and variation in developmental programs.