El-Sabaawi Rana W, Warbanski Misha L, Rudman Seth M, Hovel Rachel, Matthews Blake
Department of Biology, University of Victoria, P.O. Box 1700, Station CSC, Victoria, BC, V8W 2Y2, Canada.
Department of Zoology, University of British Columbia, 4200-6270 University Boulevard, Vancouver, BC, V6T 1Z4, Canada.
Oecologia. 2016 Aug;181(4):1209-20. doi: 10.1007/s00442-016-3599-0. Epub 2016 Apr 13.
Understanding how trait diversification alters ecosystem processes is an important goal for ecological and evolutionary studies. Ecological stoichiometry provides a framework for predicting how traits affect ecosystem function. The growth rate hypothesis of ecological stoichiometry links growth and phosphorus (P) body composition in taxa where nucleic acids are a significant pool of body P. In vertebrates, however, most of the P is bound within bone, and organisms with boney structures can vary in terms of the relative contributions of bones to body composition. Threespine stickleback populations have substantial variation in boney armour plating. Shaped by natural selection, this variation provides a model system to study the links between evolution of bone content, elemental body composition, and P excretion. We measure carbon:nitrogen:P body composition from stickleback populations that vary in armour phenotype. We develop a mechanistic mass-balance model to explore factors affecting P excretion, and measure P excretion from two populations with contrasting armour phenotypes. Completely armoured morphs have higher body %P but excrete more P per unit body mass than other morphs. The model suggests that such differences are driven by phenotypic differences in P intake as well as body %P composition. Our results show that while investment in boney traits alters the elemental composition of vertebrate bodies, excretion rates depend on how acquisition and assimilation traits covary with boney trait investment. These results also provide a stoichiometric hypothesis to explain the repeated loss of boney armour in threespine sticklebacks upon colonizing freshwater ecosystems.
理解性状多样化如何改变生态系统过程是生态与进化研究的一个重要目标。生态化学计量学提供了一个预测性状如何影响生态系统功能的框架。生态化学计量学的生长率假说将核酸是体内磷的重要储存库的生物类群中的生长与磷（P）的身体组成联系起来。然而，在脊椎动物中，大部分磷结合在骨骼中，具有骨骼结构的生物在骨骼对身体组成的相对贡献方面可能存在差异。三刺鱼种群的骨板甲存在显著差异。在自然选择的作用下，这种差异提供了一个模型系统，用于研究骨含量的进化、元素身体组成和磷排泄之间的联系。我们测量了甲胄表型不同的三刺鱼种群的碳：氮：磷身体组成。我们开发了一个机械质量平衡模型来探索影响磷排泄的因素，并测量了两个具有不同甲胄表型的种群的磷排泄量。完全披甲的形态具有更高的身体磷含量百分比，但每单位体重排泄的磷比其他形态更多。该模型表明，这种差异是由磷摄入量的表型差异以及身体磷含量组成驱动的。我们的结果表明，虽然对骨骼性状的投入会改变脊椎动物身体的元素组成，但排泄率取决于获取和同化性状与骨骼性状投入的协变方式。这些结果还提供了一个化学计量学假说来解释三刺鱼在 colonizing 淡水生态系统时反复失去骨板甲的现象。 （注：原文中“colonizing”可能有误，推测可能是“colonizing”，这里按推测翻译为“殖民化，开拓”，具体需结合更准确原文确定）
