Plant pathogens and tropical tree diversity

植物病原体和热带树木多样性

• 批准号: NE/D010721/1
• 负责人: Owen Lewis
• 金额: $ 59.45万
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2007
• 资助国家: 英国
• 起止时间: 2007 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FD010721%2F1
• 关键词: Plant; pathogens; tropical; tree; diversity

At least half of all the earth's species of plants and animals live in tropical forests, and there is considerable interest in the ecological processes maintaining this extraordinary diversity. Explaining the high diversity of tropical trees is a particular challenge, because most plant species use very similar resources: just one or a few highly competitive species might be expected to dominate the forest, rather than the hundreds of species per hectare that are often observed. If we can explain the high diversity of tropical trees, then the high diversity of other taxa in tropical forests may follow. Recently, evidence has been growing that high plant diversity in tropical forests arises because of strong density-dependent seed and seedling mortality. In other words, seeds and seedlings are more likely to die when close to their parent tree and close to other seedlings of the same species. This puts locally rare plant species at an advantage, preventing any one species from reaching high abundance. It is widely suspected that fungus-like plant pathogens are responsible for seedling density-dependence. However, the evidence for their role in maintaining high plant diversity in tropical forests is largely circumstantial, and their effects on the wider structure of tropical forest communities have not been explored fully . We will test the hypothesis that plant pathogens maintain high plant diversity at our study site in Belize, Central America. We will address five key outstanding questions: (i) How widespread is pathogen mediated density-dependence? For pathogens to play an important structuring role in tropical forest communities, their effects must be widespread. Exclusion experiments using selective fungicides will reveal whether pathogens are driving density-dependent mortality. (ii) Are pathogens specialist or generalist? Density dependence is expected to have the strongest diversity-enhancing role when natural enemies show high host specificity. Molecular and experimental approaches will be used to assess the specificity of pathogen species and strains isolated from seedlings of individual tropical tree species. (iii) Do pathogens mediate indirect interactions among plant species? We will assess the extent to which pathogens are shared between pairs of plant species, and investigate the community-wide impacts of shared parasitism. (v) How do pathogens affect the relationship between host density and mortality? We will determine whether the the relationship between density and mortality is of a form likely to promote plant diversity, and we will determine the relative importance of density and distance from parent tree in influencing mortality. (iv) Does mortality from pathogens increase diversity? We will carry out the first experimental test of the hypothesis that pathogens promote plant diversity by comparing the diversity of the seed rain with the diversity of new seedlings in fungicide-treated and untreated plots.

地球所有物种中至少有一半生活在热带森林中，并且对维持这种非凡多样性的生态过程充满了兴趣。解释热带树的高度多样性是一个特殊的挑战，因为大多数植物物种都使用非常相似的资源：可能只有一种或几种高度竞争的物种可以占主导地位，而不是经常观察到的每公顷数百种。如果我们可以解释热带树的高度多样性，那么可能会随后在热带森林中其他分类单元的多样性。最近，有证据表明，由于密度依赖性种子和幼苗死亡率强，热带森林中的植物多样性高。换句话说，当种子和幼苗靠近父母并靠近同一物种的其他幼苗时，种子和幼苗更有可能死亡。这使本地稀有的植物物种有优势，从而阻止了任何一种物种达到高丰度。人们普遍怀疑真菌样植物病原体是幼苗密度依赖性的原因。但是，它们在热带森林中维持高植物多样性中作用的证据在很大程度上是间接的，并且尚未充分探索它们对热带森林社区更广泛结构的影响。我们将检验以下假设：植物病原体在中美洲伯利兹的研究地点保持植物多样性。我们将解决五个关键问题：（i）病原体介导的密度依赖性如何普遍？要使病原体在热带森林社区中起重要的结构作用，它们的影响必须广泛。使用选择性杀菌剂的排除实验将揭示病原体是否正在驱动密度依赖性死亡率。 （ii）病原体专家还是通才？当天然敌人表现出较高的宿主特异性时，预计密度依赖性具有最强的多样性作用。分子和实验方法将用于评估从单个热带树种幼苗中分离出的病原体物种的特异性和菌株。 （iii）病原体是否介导植物物种之间的间接相互作用？我们将评估在植物物种对之间共享病原体的程度，并研究共同寄生虫的社区范围内的影响。 （v）病原体如何影响宿主密度与死亡率之间的关系？我们将确定密度和死亡率之间的关系是否具有可能促进植物多样性的形式，我们将确定密度和与父树的相对重要性在影响死亡率的情况下。 （iv）病原体的死亡率是否增加了多样性？我们将进行首次实验测试，以实验假设，即病原体通过比较种子雨的多样性与杀菌剂治疗和未处理地块中新幼苗的多样性来促进植物的多样性。

项目成果

Dung Beetles Reduce Clustering of Tropical Tree Seedlings

粪甲虫减少热带树苗的聚集

• DOI: 10.1111/j.1744-7429.2012.00871.x
• 发表时间: 2012
• 期刊: Biotropica
• 影响因子: 2.1
• 作者: Lawson C

Testing for enemy-mediated density-dependence in the mortality of seedlings: field experiments with five Neotropical tree species

• DOI: 10.1111/j.1600-0706.2013.00835.x
• 发表时间: 2014-02-01
• 期刊: OIKOS
• 影响因子: 3.4
• 作者: Gripenberg, Sofia;Bagchi, Robert;Lewis, Owen T.
• 通讯作者: Lewis, Owen T.

Consequences of changing rainfall for fungal pathogen-induced mortality in tropical tree seedlings.

• DOI: 10.1002/ece3.252
• 发表时间: 2012-07
• 期刊: ECOLOGY AND EVOLUTION
• 影响因子: 2.6
• 作者: Swinfield, Tom;Lewis, Owen T.;Bagchi, Robert;Freckleton, Robert P.
• 通讯作者: Freckleton, Robert P.