Theory of Biodiversity, Extinction and Habitat Change on Islands and Mainlands

世界范围内的生物多样性正在以可怕的速度下降；保护问题在社会上从未如此突出。人类正在改变自然世界，但对其长期后果只有基本的了解。我的目标是开发和使用新的方法来理解清除或改变自然栖息地将如何影响通常产生和维持生物多样性的过程。我将重点讨论两个系统：偏远的岛屿群和热带雨林。雨林工作将与SAFE项目合作进行：“改变的森林生态系统的稳定性”。根据外管局的协议，2011年，当一大片雨林被砍伐用于油棕种植园时，种植园内精心挑选的森林将不受影响。这使得SAFE成为世界上最大的生态实验之一；它将收集2011年前后的大量数据。预测是非常困难的，尤其是对未来的预测。（物理学家尼尔斯·玻尔）为了预测部分被砍伐的自然栖息地未来的生物多样性损失，最常用的是一个简单的数学公式，它将该地区的物种数量作为面积的函数。然而，我们也对剩下的物种有多常见或稀有以及雨林和油棕的空间安排如何发挥作用感兴趣。此外，许多雨林物种可以在油棕中生存，所以这与完全破坏栖息地是不一样的。为了考虑到这些额外的因素，我将开发一种模拟方法，能够通过从计算机生成的森林中采样个体来模拟大面积的森林，其方式与从真实森林中采样的方式大致相同。我将对生物多样性如何随着时间的推移对栖息地的改变做出一般性的预测，并将这些预测与外管局收集的数据进行比较。为了在岛屿上建立生物多样性模型，我将面临其他挑战：对于靠近大陆的岛屿，公认的理论是，在大陆物种的迁移和当地物种的灭绝之间存在着一种自然平衡。这一经典理论并不适用于更遥远的岛屿，那里的特有物种有望进化。在更遥远的岛屿上，在移民、灭绝和新物种进化之间存在着更为复杂的平衡。岛屿通常是成群的，所以移民必须在每一对可能的岛屿之间进行考虑。我将从进一步发展岛屿及其生物多样性模型开始，这是一个与生态学和进化相联系的特别有趣的研究领域。这些模型将跟随移民进入群岛的过程，因为他们改变了他们的丰度，并可能在每个岛屿上形成不同的物种。之后，我将运用这一点来研究栖息地改变和大陆移民增加对岛屿的影响。热带雨林和遥远的群岛都对生物多样性作出了重要贡献，并受到类似因素的威胁；尤其是栖息地的破坏。岛屿上生长着许多其他地方不存在的特有物种，而雨林因其所生长的物种数量之多而具有价值。可以使用类似的技术方法对这两个系统进行建模，并在它们之间进行比较。我发现这个话题令人兴奋，因为它解决了社会的重要问题。我们必须能够根据能够预测我们行为后果的理论，对保护做出明智的决定。此外，我的项目包含重大但并非不可克服的技术挑战，这将充分利用我现有的技能和经验。我相信，像我提出的计算机模拟将在未来的生态学和保护研究中发挥越来越重要的作用；我很高兴有机会在未来扮演一个角色。

Biodiversity is declining worldwide at a frightening rate; never before have the issues of conservation been more prominent in society. Humans are changing the natural world, with only a basic understanding of the long-term consequences. I aim to develop and use new ways of understanding how clearing or modifying natural habitats will impact the processes that normally generate and maintain biodiversity. I will focus on two systems: remote groups of islands and tropical rainforests. The rainforest work will be carried out in partnership with project SAFE: 'Stability of Altered Forest Ecosystems'. SAFE has negotiated that, when a large region of rainforest is cleared for an oil palm plantation during 2011, carefully chosen patches of forest will be left untouched within the plantation. This makes SAFE one of the world's largest ecological experiments; it will collect extensive data both before and after 2011. 'Prediction is very difficult, especially about the future.' (Niels Bohr, Physicist.) To predict future biodiversity loss in partly cleared natural habitat, a simple mathematical formula is most commonly used which gives the number of species in the region as a function of area. However, we are also interested in how common or rare the remaining species are and how the spatial arrangement of the rainforest and oil palm plays a role. Furthermore, many rainforest species can live in oil palm so this is not the same as total habitat destruction. To account for these additional factors, I will develop a simulation approach capable of modelling a large area of forest by sampling individuals from the computer-generated forest in much the same way as they would be sampled from a real forest. I will make general predictions about how biodiversity will respond to the habitat modification over time and will compare these to data collected by SAFE. For modelling biodiversity on islands I will face other challenges: the accepted theory for islands close to the mainland is that a natural balance exists between the immigration of species from the mainland and the loss of species through local extinction. This classic theory does not cover more distant islands, where endemic species are expected to evolve. On more distant islands, a more complex balance exists between immigration, extinction and the evolution of new species. Islands are often in groups, so immigration must be considered between every possible pair of islands. I will begin by developing further models for islands and their biodiversity, a particularly interesting area of research that links to both ecology and evolution. These models will follow the progress of immigrants onto the archipelago as they change their abundance and possibly form different species on each island. Later, I will apply this to study the effects on islands of habitat modification and increased immigration from the mainland. Both rainforests and distant archipelagos contribute in important ways to biodiversity and are threatened by similar factors; especially habitat destruction. Islands support many endemic species that exist nowhere else, whilst rainforests are valuable for the shear number of species they support. Similar technical methods can be used for modelling both systems and comparisons can be made between them. I find this topic exciting because it addresses import issues for society. We must be able to make informed decisions about conservation based on theory that can predict the consequences of our actions. Furthermore my project contains significant, yet not insurmountable technical challenges, which will make the very best use of my existing skills and experience. I believe that computer simulations such as the ones I propose will have an increasingly important role in future research into ecology and conservation; I am thrilled at having the chance to play a role in that future.