The role of dispersal in species' ability to respond to climate change

一个逐渐形成的共识是，许多动物物种正在通过将它们的分布向北转移来应对当前的气候变暖。然而，为了追踪气候，物种必须能够在被人类活动大大改变的景观中分散开来，在这些景观中，繁殖栖息地往往是破碎的，分散在不适宜居住的城市和农业景观中。由于这种人类造成的栖息地丧失，许多传播能力差的物种无法改变它们的活动范围，也无法到达超出其现有活动范围的新地点。预测为什么一些物种可以根据气候变化改变它们的活动范围，而另一些却不能，这对于改善我们对物种未来分布的预测至关重要。这个项目将通过调查物种的扩散行为和能力来解决这个问题。即使温室气体排放立即大幅减少，由于地球气候系统的惯性，仍会出现更多的变暖。因此，无论是否采取任何缓解措施，都要对未来变暖作出承诺，在这种情况下，迫切需要采取适应措施。一种普遍提出的适应措施是创造更具渗透性的景观，使物种能够在退化的景观中移动，并帮助它们在新的地点定居。然而，改善栖息地连通性以促进范围转移的有效性基本上未经检验。目前还没有数据研究物种的飞行行为对景观特征的反应如何影响它们长距离分散、定居新地点的能力，从而改变它们的活动范围。然而，这些信息对于理解气候变化对生物多样性分布的影响至关重要。这项被提议的工作将首次对碎片化景观中“日常”的本地飞行行为如何转化为长距离分散和殖民化的成功进行调查。我们将以蝴蝶为研究对象，收集蝴蝶在繁殖地、非繁殖地和栖息地/非栖息地斑块边界上的飞行路径特征（位移、飞行速度、方向性等）的新野外数据。我们将把运动信息和蝴蝶行为（产卵、采蜜等）纳入空间明确的动态模型中，以估计“真实”研究景观中的运动。我们将通过将模型运动与从同一物种和研究景观的独立标记-再捕获数据中获得的运动进行比较，来测试我们模型的可靠性。然后，我们将使用经过验证的模型来检查飞行行为的变化和繁殖栖息地的可用性如何影响研究景观中的运动概率。我们的模型还将允许我们检查保护管理计划的有效性，以改善景观连通性（影响计划）。该项目将产生具有相当实用价值的结果，并解决有关物种范围扩散限制的基本问题。这将为理解和预测气候变化对生物多样性的影响开辟一条新的研究途径。保护策略必须包括适应策略，但保护主义者不确定该怎么做。拟议的工作将为这场辩论提供具体的科学证据。

There is an emerging consensus that many animal species are responding to current climate warming by shifting their distributions northwards. However, in order to track climate, species must be able to disperse through landscapes that have been greatly altered by human activities, and where breeding habitats are often fragmented and scattered across inhospitable urban and agricultural landscapes. Because of this human-induced habitat loss, many species with poor dispersal ability are failing to shift their ranges and are unable to reach new sites beyond their current range margin. Predicting why some species can shift their ranges in response to climate change whilst others cannot, is crucial for improving our projections of species' future distributions. This project will address this issue by investigating species' dispersal behaviour and capability. Even if greenhouse gas emissions were greatly reduced immediately, more warming would still occur due to inertia in the Earth's climate system. Thus, there is a commitment to future warming regardless of any mitigation and, in this context, adaptation measures are required urgently. One commonly suggested adaptation measure is the creation of more permeable landscapes that enable species to movement through degraded landscapes, and help them colonise new sites. However, the effectiveness of improving habitat connectivity for promoting range shifts is essentially untested. There are currently no data examining how species' flight behaviour in response to landscape features may affect their ability to disperse over longer-distances, colonise new sites, and hence shift their ranges. Yet such information will be crucial for understanding the impacts of climate change on the distribution of biodiversity. The proposed work will provide the first investigation of how 'everyday' local flight behaviour in fragmented landscapes translates into longer-distance dispersal and colonisation success. We will focus on butterflies and collect new field data on butterfly flight path characteristics (displacement, speed of flight, directionality, etc) within breeding habitats, within non-breeding habitats, and at habitat/non-habitat patch boundaries. We will incorporate movement information and butterfly behaviour (ovipositing, nectaring, etc) into spatially-explicit dynamic models to estimate movements in 'real' study landscapes. We will test the reliability of our models by comparing modelled movements with those obtained from independent mark-recapture data for the same species and study landscapes. We will then use validated models to examine how variation in flight behaviour and availability of breeding habitat affects the probability of movement in study landscapes. Our models will also allow us to examine the effectiveness of conservation management plans to improve landscape connectivity (Impact Plan). The project will produce results of considerable practical value, as well as addressing fundamental questions about dispersal limits to species ranges. It will open up a new avenue of research on understanding and predicting the impacts of climate change on biodiversity. Conservation strategies must include adaptation strategies, but conservationists are uncertain about what to do. The proposed work will provide a concrete body of scientific evidence to inform this debate.