SG: Preference by birds for rare species of fruits and its role in maintaining diversity in plant communities

该项目旨在更好地了解鸟类水果选择的过程，进而了解水果选择如何影响植物群落的多样性和组成。绝大多数木本植物物种--特别是在最多样化的森林中--依靠吃水果的鸟类来散播种子，但在社区层面上缺乏关于影响水果选择和种子传播的因素的信息。该项目将通过在美洲各地的观察和实验来解决这一缺陷。这项研究的首要目标是检验这样一个假设，即不同大小和类别的食果鸟增加了环境中稀有植物物种的扩散速度。更好地了解鸟类种子的传播对于推进生态学至关重要，因为植物种群依赖种子传播来再生、共存、殖民新的地区、改变地理范围以及应对气候和其他环境变化。除了推进基础科学，这项研究产生的知识将对林业、自然资源管理、恢复生态学和保护产生积极影响。这些活动将对研究生和本科生进行培训，扩大少数民族在科学领域的教育和参与，同时促进研究人员与来自美国、秘鲁和阿根廷的学生之间的国际合作与交流。现有的理论和实证工作表明，负密度依赖(NDD)的平衡和稳定机制通过赋予群落中相对稀有的物种优势，在维持物种多样性方面发挥着关键作用。这个项目将研究一类鲜为人知的NDD过程，如果被证明是广泛发生的，可能对维持多样性和构建植物-果食性互惠群落非常重要：反根茎结实和种子传播。当物种的果实在鸟类等共享食果性种子传播剂的植物群落中相对稀少时，反背离果树将导致不成比例的高种子传播量。为了检验抗滞育果树的普遍性，这项研究将在四个大陆地区进行实地研究，代表四个不同的植物-果食性群落。这些群落提供了完全独立的生物和非生物成分，可以用来测试抗倒伏果树的发生和数量，因为它们位于一个纬度梯度上：从北美东部(宾夕法尼亚州)到南美洲南部(巴塔哥尼亚)，包括两个秘鲁森林遗址(Madre de Dios的低地亚马逊雨林和Abra Patricia的安第斯云雾森林)。除了观察水果的消费和植物种群，还将进行使用天然和人造水果展示的受控水果选择实验。

This project aims to better understand the process of fruit-selection in birds, and in turn, how fruit-selection affects the diversity and composition of plant communities. The vast majority of woody plant species - especially in the most diverse forests - depend on fruit-eating birds to disperse their seeds, but information on the factors governing fruit choice and seed dispersal at a community level is lacking. This project will address this shortcoming through observations and experiments across the Americas. The overarching goal of the research is to test the hypothesis that fruit-eating birds of different sizes and classes increase dispersal rates for plant species that are proportionally rare in the environment. Achieving a better understanding of seed dispersal by birds is critically important to advancing ecology, since plant populations depend on seed dispersal to regenerate, coexist, colonize new areas, shift geographic ranges, and cope with climatic and other environmental changes. Beyond advancing basic science, the knowledge generated by this research will have positive implications for forestry, natural resource management, restoration ecology, and conservation. The activities will result in the training of graduate and undergraduate students, and broaden the education and participation of minorities in the sciences while fostering international collaboration and exchanges between researchers and students from the USA, Peru, and Argentina. Existing theory and empirical work suggest that equalizing and stabilizing mechanisms involving negative density-dependence (NDD) play key roles in the maintenance of species diversity by conferring advantages to species that are relatively rare in communities. This project will study a little known class of NDD process that, if proven to be of widespread occurrence, can be important for diversity maintenance and the structuring of plant-frugivore mutualistic communities: antiapostatic frugivory and seed dispersal. Antiapostatic frugivory would result in disproportionately high seed dispersal when species' fruits are relatively rare in communities of plants that share frugivorous seed dispersal agents such as birds. To examine the generality of antiapostatic frugivory, this research will conduct field studies in four continental localities representing four distinct plant-frugivore communities. These communities provide fully independent biotic and abiotic elements in which to test occurrence and magnitude of antiapostatic frugivory as they are located across a latitudinal gradient: from eastern North America (Pennsylvania) to southern South America (Patagonia), including two Peruvian forest sites (lowland Amazonian rainforest at Madre de Dios, and an Andean cloud forest at Abra Patricia). In addition to observations of fruit consumption and plant demography, controlled fruit-selection experiments using natural and artificial fruit displays will be conducted.