The functional ecology of an adaptive radiation: stable isotopes, niches, phylogenies and kidneys

尽管鸣禽是最多样化的鸟类谱系，并且几乎占据了地球上每一个陆地栖息地，但鸣禽（雀形目，或栖息的鸟类）很少适应成为海洋专家。雀鸟中海洋物种的稀少可能是由于缺乏功能性盐腺和鸟类肾脏相对无法产生高浓度尿液，这使它们无法应对伴随海洋资源而来的盐负荷。这个项目将追踪一组南美鸣禽在进化辐射中形成海洋生态位的进化路径，其中两个物种独立地成为海洋专家。该小组还包括淡水专家和同时占据淡水和海洋栖息地的物种。我们还将研究促进从淡水环境向海洋环境过渡的生理机制。实现这些目标需要三种互补的方法：1)使用分子技术来阐明群体中物种之间的进化关系；2)利用稳定同位素量化这些物种对海洋资源的相对依赖；3)利用生理和形态测量来评估使海洋物种能够应对伴随海洋资源使用而来的盐负荷的特征。这个项目基本上是跨学科的，因此它的参与者包括一位生理学家、一位系统发育学家和一位统计学家。该项目也是一个国际合作项目，包括来自智利和巴西的科学家。远征生理学旨在探索地球的功能性生物多样性，该项目是交流生物学和激励年轻学者的理想工具。这个项目是与怀俄明州的小学和中学教师合作，开发课堂练习和互动的、基于网络的虚拟探险，以便他们的学生能够进行研究。

Despite their status as the most diverse lineage of birds and their occupation of nearly every terrestrial habitat on the planet, songbirds (passerines, or perching birds) have rarely adapted to become marine specialists. The paucity of marine species among passerines is probably due to the absence of functional salt glands and to the relative inability of bird kidneys to produce highly concentrated urine, which prevents them from coping with the salt loads that accompany marine resources. This project will track the evolutionary pathways that led to a marine niche in an evolutionary radiation of a group of South American songbirds in which two species have independently become marine specialists. The group also includes freshwater specialists and species that occupy both freshwater and marine habitats. We will also investigate the physiological mechanisms that facilitated the transition from a freshwater to a marine environment. Achieving these objectives demands three complementary approaches: 1) using molecular techniques to elucidate the evolutionary relationship among the species in the group; 2) using stable isotopes to quantify the relative reliance of each of these species on marine resources, and 3) using physiological and morphological measurements to assess the traits that allow marine species to cope with the salt loads that accompany the use of marine resources. This project is fundamentally interdisciplinary and hence its participants include a physiologist, a phylogenetic systematist, and a statistician. The project is also an international collaboration that includes scientists from Chile and Brazil. Expeditionary physiology aims to explore the planet's functional biodiversity, and this project is an ideal instrument for communicating biology and inspiring young scholars. This project is a collaboration with elementary and middle school teachers across Wyoming to develop classroom exercises and interactive, web-based, virtual expeditions in order to make the research accessible to their students.