Ecological and evolutionary effects of climate change on rainforest food webs

生态群落是复杂的、相互作用的物种网络，通过竞争、互惠、捕食和寄生联系在一起。在《物种起源》一书中，查尔斯达尔文（Charles Darwin）有一个著名的描述：“一个纠缠在一起的银行”，包括令人眼花缭乱的丰富物种和它们之间更复杂的联系网。从根本上说，生态学家和进化生物学家试图解开这种复杂性，通过建立为什么物种会出现在他们所做的地方，为什么他们在某些条件下相互取代，以及组成生态系统的物种相互作用如何随着环境的变化而变化。随着气候变暖和极端事件变得更加频繁，物种之间现有的联系正在改变强度，或完全切断;随着物种数量的变化和分布的变化，新的联系正在形成（例如，殖民较冷的栖息地，而在温暖的栖息地灭绝）。生物学家利用物种目前出现的温度范围的信息来预测物种在未来更温暖的世界中会出现在哪里。然而，如果我们也能考虑到物种之间不断变化的相互作用，以及物种进化以科普新条件的潜力，那么就有可能更好地预测气候变化的后果。我们迫切需要测试相互作用物种的整个食物网是如何通过生物过程构建的（例如竞争和捕食）和温度的影响，以及这些生态网络将如何应对气候变化。同样重要的是，要测试目前物种地理范围内的适应性差异将在多大程度上提高它们对未来气候变化的适应能力。为了实现这一目标，我们的项目将在受气候变化威胁的高多样性生态系统（澳大利亚热带雨林）中利用一个独特的模型系统（果蝇和与它们相关的寄生蜂，称为寄生蜂）。利用这一系统，我们将通过野外观测、野外移植实验和数学模型来检验：（i）是什么决定了物种的局部分布和食物网结构;（ii）自然和模拟的物种相互作用网络对模拟气候变化的反应;以及（iii）推动这些变化的潜在机制，包括物种内种群间遗传变异的影响和迅速进化适应温暖温度的潜力。其结果将是更好和更有预见性地了解气候变化将如何影响生物相互作用，而生物相互作用是生物多样性的基础，也是自然生态系统功能和服务的基础。

Ecological communities are complex, interacting networks of species, linked by competition, mutualism, predation and parasitism. In the 'Origin of Species', Charles Darwin famously wrote of 'an entangled bank', comprising a bewildering richness of species and an even more complex web of connections among them. Fundamentally, ecologists and evolutionary biologists seek to unravel this complexity, by establishing why species occur where they do, why they replace each other under certain conditions, and how the species interactions that make up ecosystems will change as environments change. As the climate warms and extreme events become more frequent, existing connections between species are changing in strength, or being severed completely; and new connections are forming as species change in abundance and shift their distributions (e.g. colonising cooler habitats, while becoming locally extinct in warmer habitats). Biologists use information about the range of temperatures where species currently occur to predict where species will occur in a future, warmer world. However, better predictions about the consequences of climate change will be possible if we can also take into account changing interactions between species, as well as the potential for species to evolve to cope with new conditions.We urgently need to test how whole food webs of interacting species are structured by biological processes (e.g. competition and predation) and by temperature, and how these ecological networks will respond to climate change. It is also important to test the extent to which current adaptive divergence across species' geographical ranges will increase their resilience to future climate change. To achieve this, our project will exploit a unique model system (Drosophila fruit-flies and parasitic wasps that are associated with them, called parasitoids) in a high-diversity ecosystem threatened by climate change (Australian tropical rainforests). With this system we will use field observations, field transplant experiments and mathematical models to test: (i) what determines species' local distributions and food web structure; (ii) the responses of natural and simulated networks of interacting species to simulated climate change; and (iii) the underlying mechanisms driving these changes, including the effects of genetic variation among populations within species and the potential for rapid evolutionary adaptation to warmer temperatures. The outcome will be a better and more predictive understanding of how climate change will affect the biotic interactions that characterise biodiversity and underpin the functions and services of natural ecosystems.