Exchanges of enemies between native and non-native plants

本地植物和非本地植物之间的天敌交换

• 批准号: RGPIN-2016-06095
• 负责人: Kotanen, Peter
• 金额: $ 2.04万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=616096
• 关键词: Exchanges; enemies; between; native; non

Escape from native-range natural enemies (herbivores and pathogens) often is argued to increase the invasiveness of non-native plants, as described by the Enemy Release Hypothesis. However, once in a new region, exotic invaders acquire new enemies recruited from invaded-range species. As well, enemies from the invader's original range (including biocontrol agents) may be accidentally or deliberately co-introduced; these species also may attack local natives. As a result, few invaders are free of natural enemies, many of which are shared with co-occurring native plants. Shared enemies can have significant impacts on invaders, reducing their success through biotic resistance. As well, shared enemies may participate in feedbacks on natives through spillover (spread of introduced enemies from exotic hosts to natives) and spillback (spread of native enemies to exotics followed by spread back onto their original hosts); these feedbacks constitute an important but underexplored component of invaders' ecological impacts. However, not all invasive populations may be equally affected by such interactions. First, the probability of exchange is likely to be lower between more distantly-related natives and exotics. Second, plants that are spatially isolated from sources of enemies may experience reduced exchange. Third, populations of enemies may vary regionally, resulting in geographic trends in exchange. Fourth, even if enemies are shared, tolerance to damage may reduce their effects in favourable habitats. Finally, impacts such as herbivory are likely to be most critical for small populations of invaders; this is the stage at which most unsuccessful invasions fail. Here, I propose to investigate key factors that affect the exchange of enemies between natives and exotics, and the consequences for the performance of both. We will experimentally test the importance of phylogeny, spatial isolation, and geographic variation for shared enemies, will evaluate the role of tolerance in mitigating these impacts, and will investigate factors affecting the success of small populations. By illuminating the complex web of interactions surrounding invasive plants, this novel research will clarify the importance of shared enemies to the spread of exotics and their impacts on co-occurring natives, and will contribute to my long-term objective of understanding interactions between invasive plants and their natural enemies.

正如“天敌释放假说”所描述的那样，逃离本地天敌（食草动物和病原体）通常被认为会增加非本地植物的入侵性。然而，一旦进入新的地区，外来入侵者就会从入侵物种中招募新的敌人。同样，来自入侵者原始范围的敌人（包括生物防治剂）可能会被意外或故意地共同引入；这些物种也可能攻击当地土著。因此，几乎没有入侵者没有天敌，其中许多天敌是与共生的本土植物共有的。 共同的敌人会对入侵者产生重大影响，通过生物抵抗降低入侵者的成功率。同样，共同的敌人可能通过溢出（将引入的敌人从外来宿主传播到本地人）和溢出（本地敌人传播到外来人，然后传播回其原始宿主）来参与对本地人的反馈；这些反馈构成了入侵者生态影响的一个重要但尚未得到充分研究的组成部分。然而，并非所有入侵种群都会同样受到这种相互作用的影响。首先，关系较远的本地人和外来人之间交换的可能性可能较低。其次，在空间上与天敌来源隔离的植物可能会减少交换。第三，敌人的数量可能因地区而异，从而导致交换的地理趋势。第四，即使有共同的敌人，对伤害的容忍也可能会减少它们对有利栖息地的影响。最后，食草等影响可能对小群入侵者最为严重。这是大多数不成功的入侵失败的阶段。 在这里，我建议调查影响本地人和外来人之间敌人交换的关键因素，以及对两者表现的影响。我们将通过实验测试系统发育、空间隔离和地理变异对共同敌人的重要性，评估宽容在减轻这些影响中的作用，并将调查影响小种群成功的因素。通过阐明入侵植物周围复杂的相互作用网络，这项新颖的研究将阐明共同敌人对于外来物种传播的重要性及其对共存本地植物的影响，并将有助于我了解入侵植物与其天敌之间相互作用的长期目标。