Fruit and seed secondary metabolites and animal seed handling: impacts on germination success and seedling survival

没有一个物种可以孤立地生存。即使是可以自己制造食物的植物，也要依靠动物为它们的花授粉并将种子传播到新的地方。随着地球上生物多样性的持续下降，了解我们希望保护的物种之间的相互依赖关系变得越来越紧迫。这项研究的目的是加深我们对维持热带森林生物多样性的植物和传播种子的动物之间相互作用的理解。为了吸引动物，植物会结出富有吸引力和营养的果实。然而，水果不仅仅是美味的奖励。除了营养，水果还会产生天然化合物，影响食用它们的动物的行为和生理。例如，水果中的某些化合物对动物有通便作用，这可能是植物影响种子与亲本运输距离的一种方式。本研究将探讨果实和种子化学、动物行为和生理以及种子萌发和存活之间的关系。这些信息可以帮助科学家更好地保护热带森林的生物多样性，并以最大限度地提高种子发芽和存活率的方式管理恢复目标区域。该项目将产生新的热带森林生态教育资源，这些资源将在当地的自然中心和弗吉尼亚州的科学节中广泛共享。此外，实地和实验室的各种研究活动将有助于培养下一代科学家，包括拉丁裔学生，他们将成为中美洲和南美洲热带森林的未来管家。该项目将重点关注最丰富和最多样化的热带植物群体之一——胡椒属辣椒植物——与它们赖以传播种子的动物之间的相互作用。这些动物中最引人注目的是果蝠，它们吃水果（和它们所含的种子），然后把种子排泄到新的地方。然而，还有另一种动物对扩散起着至关重要的作用——蚂蚁。虽然蚂蚁很小，但它们是热带森林中数量最多的动物，它们会迅速到达蝙蝠掉落的部分被吃掉的水果，或者到达蝙蝠粪便中沉积的种子。一些种子被蚂蚁吃掉，但许多种子和果肉一起被移走，短距离移动，然后被丢弃。为了评估果实和种子化学在决定这些相互作用结果中的作用，研究人员将在哥斯达黎加的La Selva生物站进行三个实验。首先，由于人们对水果化学对散播种子的蚂蚁的影响一无所知，他们将测试水果化学如何影响被蚂蚁带走的种子的命运——也就是说，这些种子是被吃掉、储存还是丢弃。这将包括对圈养蚁群的实验，研究人员可以追踪单个种子的命运。其次，研究人员将调查蝙蝠、蚂蚁或蝙蝠和蚂蚁的结合如何影响种子的化学成分。第三，研究人员将在最后的实验中使用蝙蝠和蚂蚁处理方式不同的种子，以确定化学和动物处理方式如何影响种子发芽和存活的最终概率。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

No species can survive in isolation. Even plants, which can make their own food, depend on animals to pollinate their flowers and disperse their seeds to new sites. As the biological diversity on our planet continues to decline, it is becoming increasingly urgent to understand the interdependencies among the species that we hope to protect. The aim of this research is to deepen our understanding of interactions between plants and the seed-dispersing animals that sustain the biodiversity of tropical forests. To attract animals, plants produce fruits that are attractive and nutritious. However, fruits are much more than tasty rewards. In addition to nutrients, fruits produce natural chemical compounds that can influence the behavior and physiology of animals that consume them. For example, certain compounds in fruits have a laxative effect on animals, which could be a way for plants to influence how far the seed is transported from the parent. This research will investigate the relationships among fruit and seed chemistry, animal behavior and physiology, and seed germination and survival. This information can help scientists better protect the biodiversity of tropical forests and manage areas targeted for restoration in a way that will maximize seed germination and survival. The project will generate new educational resources on tropical forest ecology, which will be shared broadly at a local nature center and through science festivals in Virginia. Additionally, the diverse research activities in the field and lab will help train the next generation of scientists, including Latino(a) students who will be the future stewards of tropical forests in Central and South America. The project will focus on interactions between one of the most abundant and diverse groups of tropical plants - pepper plants in the genus Piper - and the animals they rely on to disperse their seeds. The most conspicuous of these animals are fruit bats, which consume fruits (and the seeds they contain) and later defecate the seeds in new sites. However, there is another group of animals that are critical to dispersal - ants. Although small, ants are the most abundant animals in tropical forests, and rapidly arrive at partially consumed fruits that are dropped by bats, or at seeds that are deposited in bat feces. Some seeds are consumed by ants, but many are removed along with pulp, moved short distances, and discarded. To assess the role of fruit and seed chemistry in determining the outcome of these interactions, researchers will conduct three experiments at La Selva Biological Station in Costa Rica. First, because nothing is known about the effects of fruit chemistry on seed-dispersing ants, they will test how fruit chemistry affects the fate of seeds removed by ants - that is, whether the seeds are consumed, cached, or discarded. This will involve experiments with captive ant colonies in which researchers can track the fate of individual seeds. Second, the researchers will investigate how handling by bats, ants, or the combination of bats and ants influences the chemistry of seeds. Third, the researchers will use seeds that have been differentially handled by bats and ants in a final experiment to determine how chemistry and animal handling influence the ultimate probability of seed germination and survival.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.