DISSERTATION RESEARCH: Direct and indirect effects of invasive species on plant-seed disperser mutualisms

许多植物依靠吃水果的动物来散播种子。这种相互作用对植物和动物都有好处，因此被称为互惠互利。由于种子传播可以决定植物的丰富度和范围，种子传播互惠关系可以使其他以植物为食物或庇护所的物种受益，从而影响整个景观的生物多样性格局。人类将新物种引入栖息地可能会扰乱种子传播互惠，但我们对这种扰乱可能会影响其他相互关联的物种的情况知之甚少。该项目将测试阿根廷巴塔哥尼亚北部温带森林中一种重要的种子传播互惠关系的破坏所产生的更大的生态影响。槲寄生Tristerix corymBosus是蜂鸟Sephanoides sephaniodes冬季唯一的花蜜来源，这种蜂鸟常年留在该地区，负责该地区近20%的特有木本植物的授粉。槲寄生的种子完全是由有袋动物Dromiciopsgliroides传播的。在穿过有袋类动物的肠道后，大多数排出的种子会粘在木通的树枝上，木通是森林中最丰富的林下灌木，也是槲寄生最常见的宿主。由于这些密切的生态关系，外来物种减少了Maqui的密度，也可能减少槲寄生、蜂鸟和有袋动物的数量，从而改变了整个森林。该项目将测试外来黄蜂VesPula germanica和外来有蹄类动物对Maqui种群和森林中相关物种的影响。保护生物多样性对人类社会非常重要，而人类意外和故意在世界各地引入新物种是对生物多样性的主要威胁之一。这项研究将进一步加深我们对引进物种如何影响生物多样性的理解，并有助于指导管理部门保护多样性。这项研究还将加强国际科学合作和培训。

Many plants rely on fruit-eating animals to disperse their seeds. This interaction benefits both the plant and the animal and is therefore termed a mutualism. Because seed dispersal can determine the abundance and range of the plant, seed dispersal mutualisms can benefit other species that use the plant for food or shelter and thus affect patterns of biodiversity across the landscape. The introduction by humans of new species into a habitat can disrupt seed dispersal mutualisms, but we know little about such disruptions may affect other, interrelated species. This project will test the larger ecological effects of disruption of an important seed dispersal mutualism in the northern temperate forests of Patagonia in Argentina. The mistletoe Tristerix corymbosus is the sole winter nectar source for the hummingbird Sephanoides sephaniodes, which remains in the region year-round and is in turn responsible for the pollination of nearly 20% of the endemic woody flora in the region. The seeds of the mistletoe are dispersed exclusively by the marsupial Dromiciops gliroides. After passing through the gut of the marsupial, most of the defecated seeds stick to branches of maqui, Aristotelia chilensis, the most abundant understory shrub in the forest and the most common host for the mistletoe. Because of these close ecological relationships, exotic species that reduce the density of maqui could also reduce the abundances of the mistletoe, the hummingbird, and the marsupial, changing the forest as a whole. This project will test the effects of the exotic wasp Vespula germanica and of exotic ungulates on maqui populations and on the linked species in the forest.Conservation of biological diversity is important to human society, and one of the major threats to biodiversity are the accidental and intentional introductions of new species around the world by humans. This research will further our understanding of how introduced species can affect biodiversity and help guide management to conserve diversity. The research will also strengthen international scientific collaboration and training.