The impact of competition on global-change induced range shifts in birds

许多鸟类物种目前正在经历快速的范围转移，以应对人类引起的变化。当它们的活动范围改变时，物种会遇到以前没有共存过的新物种。这个博士项目将旨在填补我们对范围动态后果的理解的关键空白，采取宏观生态学的方法来回答几个开放的问题，如：（1）新物种的相互作用如何影响范围扩张的结果？随着物种分布范围的扩大，新的物种组合出现，物种之间的竞争可能会影响范围扩大事件的动态。例如，种间竞争可能导致竞争排斥，阻止物种成功地在已经建立了类似生态位的物种的地区定居。此外，许多动物的分布受到与其他物种的领土侵略的限制，生殖干扰似乎限制了许多分类群的共存和范围扩展。然而，尽管物种相互作用在塑造物种分布范围方面的重要性得到了广泛的认可，但物种相互作用对当代分布范围扩张的影响在很大程度上是未知的。(2)剥削性竞争的相对重要性是什么（即，接入有限资源的竞争）和干扰竞争（例如，物种之间的领土侵略）在构建新的组合？虽然一些研究侧重于预测物种将如何应对随着范围的变化而对生境和资源的竞争，但对物种的社会行为如何影响范围动态知之甚少。例如，一些研究表明，领土物种可能会对密切相关的物种进行攻击，因为它们的范围扩大了，这可能会减缓范围扩大的速度。同样，理论预测繁殖干扰物种间浪费的繁殖互动应该阻止杂交物种共存，因此物种间的繁殖互动也可能减缓范围扩张的速度。然而，这些不同形式的物种相互作用的相对影响仍然未知。(3)非生物因素如气候变化和土地利用如何与分布区扩展过程中的种间竞争相互作用？虽然气候和土地利用的变化对鸟类数量和分布区动态的影响是显而易见的，但哪些因素在决定分布区变化的相对成功和失败方面起着最大的作用还不太清楚。尽管生物相互作用在形成物种分布区方面的重要性得到了广泛的认可，但确定物种相互作用在影响分布区扩张的速度或结果方面的作用的研究却令人惊讶地罕见。因此，该项目可能会产生几个高影响力的出版物。

Many species of birds are currently undergoing rapid range shifts in response to human-induced changes. As their ranges change, species encounter new species with which they hadn't before coexisted. This PhD project will aim to fill crucial gaps in our understanding of the consequences of range dynamics, taking a macroecological approach to answer several open questions, such as:(1) How do novel species interactions impact the outcome of range expansions? As species' ranges expand, novel species assemblages emerge, and competition between species may influence the dynamics of range expansion events. For instance, interspecific competition can cause competitive exclusion, preventing species from successfully colonizing areas where species occupying similar niches are already established. In addition, the distributions of many animals are limited by territorial aggression with other species, and reproductive interference appears to limit coexistence and range expansion in numerous taxa. Yet, despite broad appreciation of the importance of species interactions in shaping species' ranges, the impact of species interactions on contemporary range expansion is largely unknown. (2) What is the relative importance of exploitative competition (i.e., competition for access to limiting resources) and interference competition (e.g., territorial aggression between species) in structuring novel assemblages? Although some research has focused on predicting how species will respond to competition for access to habitat and resources as ranges change, less is known about how species' social behaviours might influence range dynamics. For instance, a few studies show that territorial species are likely to be aggressive toward closely related species as their ranges expand, which may slow down the speed at which ranges might otherwise expand. Similarly, theory predicts that reproductive interference-wasteful reproductive interactions between species-should prevent hybridizing species from coexisting, so reproductive interactions between species may also slow down the speed of range expansions. Yet, the relative impact of these different forms of species interactions remains unknown.(3) How do abiotic factors such as climate change and land use interact with interspecific competition during range expansions? While it is clear that changes in climate and land use impact bird populations and range dynamics, it is less clear which factors play the largest role in determining the relative success and failure of range shifts.Despite broad appreciation for the importance of biotic interactions in shaping species' ranges, studies that identify a role for species interactions in influencing the rates or outcomes of range expansion are surprisingly rare. Therefore, this project is likely to yield several high impact publications.