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的果实选择过程，进而了解果实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——尤其是在最多样化的森林中——依靠以水果为食的鸟类来传播它们的种子，但是关于在群落水平上控制水果选择和种子传播的因素的信息是缺乏的。本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验证这样一个假设，即不同大小和类别的以水果为食的鸟类会增加环境中比例罕见的植物物种的传播速度。更好地了解鸟类的种子传播对促进生态学至关重要，因为植物种群依靠种子传播来再生、共存、在新地区定居、转移地理范围以及应对气候和其他环境变化。除了推进基础科学之外，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。这些活动将培养研究生和本科生，扩大少数民族在科学领域的教育和参与，同时促进来自美国、秘鲁和阿根廷的研究人员和学生之间的国际合作和交流。现有的理论和实证研究表明，包括负密度依赖（NDD）在内的平衡和稳定机制通过赋予群落中相对罕见的物种优势，在物种多样性的维持中起着关键作用。该项目将研究一种鲜为人知的NDD过程，如果被证明是广泛发生的，对植物-果食性互惠群落的多样性维持和结构具有重要意义：抗离体果食性和种子传播。当物种的果实在共用果食性种子传播媒介的植物群落（如鸟类）中相对稀少时，反离源性果食性将导致不成比例的高种子传播。为了检验抗叛教果食性的普遍性，本研究将在代表四种不同植物果食性群落的四个大陆地区进行实地研究。这些群落提供了完全独立的生物和非生物元素，用于测试抗离体frugivory的发生和大小，因为它们位于纬度梯度上：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的亚马逊低地雨林和Abra Patricia的安第斯云雾林）。除了观察水果消费和植物人口统计外，还将进行使用自然和人工水果展示的对照水果选择实验。

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.