REFUGIAL POPULATIONS AT TRAILING-EDGE RANGE MARGINS: ATTRIBUTES, SURVIVAL AND CONSERVATION

在过去气候条件有利的地区，许多物种曾经广泛分布，但现在它们作为局部的难民种群存活下来。这些物种生存于与周围地区不典型的局部生境和/或小气候中；例如，当气候变暖时，英国的一种适应寒冷的物种可能会在当地寒冷的朝北地区生存。避难所在使物种在过去的气候变化中生存下来方面非常重要，并且在人为气候变化的情况下可能会再次如此。尽管如此，人们对支持人口难民的当地条件知之甚少。因此，随着气候的变化，我们对物种在未来可能持续存在的地点的属性（地点、栖息地、小气候）知之甚少。了解这些属性对于为未来的保护政策提供信息以及发展对物种地理分布动态的更深入的基础科学理解至关重要。我们将利用人为气候变化带来的机会，通过研究英国北部分布的四种蝴蝶，直接观察避难种群的形成。蝴蝶是这个项目理想的研究物种，因为在过去40年的气候变化中，英国有很好的分布记录，而且当地的小气候和微生境条件影响着蝴蝶从出生到死亡的所有生命阶段。我们将重新调查英国的一些地点，这些地点有20世纪70年代以来的历史分布数据，我们在2004- 2005年重新调查了这些地点，以确定哪些物种幸存下来，哪些物种灭绝。我们将使用包含物种环境信息的动态种群模型来确定自20世纪70年代人为气候变化开始以来种群存活的地点的当地小气候和栖息地特征。我们将通过研究其他北方无脊椎动物的气候避难所形成来检验我们的蝴蝶发现的普遍性。然后，我们将使用我们的模型来预测未来气候变化对物种的影响，直到2100年，并确定英国现有保护区位置与避难所重合的程度。这项工作将提供第一个调查和预测模型，以促进范围后退物种种群持久性的地点属性。该项目将解决气候变化下物种分布动态的基本问题，并为政策制定者提供具有相当实用价值的结果。它将为理解气候变化对生物多样性的影响开辟一条新的研究途径，并为在气候变化下制定有效的保护策略提供具体的科学证据。

Many species currently survive as localised, refugial populations in regions where they used to be more widespread under more favourable past climatic conditions. These species survive in localised habitats and/or microclimates that are atypical of the surrounding region; for example, a cold-adapted species in Britain might survive on a locally cold, north-facing site when the climate warms. Refugia have been extremely important in allowing species to survive past climatic changes, and are likely to be so again under anthropogenic climate change. Despite this, the local conditions that support population refugia are poorly understood. Thus we have little idea of the attributes (locations, habitats, microclimates) of sites where species may persist in future as the climate changes. Understanding these attributes is vital for informing future conservation policies as well as for developing a deeper fundamental scientific understanding of the dynamics of species' geographic distributions. We will take advantage of the opportunity presented by anthropogenic climate change to observe the creation of refugial populations directly, by studying four species of northerly-distributed butterflies in Britain. Butterflies are ideal study species for this project because there are excellent distribution records in Britain over the past four decades of climate change, and because local microclimate and microhabitat conditions affect all butterfly life stages, from birth to death. We will re-survey sites in Britain for which we have historical distribution data since the 1970s, and which we re-surveyed in 2004-05, to determine where species have survived, and where they have become extinct. We will use dynamic population models that incorporate environmental information for species to identify the local microclimatic and habitat characteristics of locations where populations have survived since the onset of anthropogenic climate change in the 1970s. We will examine the generality of our butterfly findings by studying climate refugial formation in other northern invertebrates. We will then use our models to project the consequences of future climatic changes for species, to the year 2100, and determine the degree to which refugia coincide with the locations of existing protected areas in Britain.The proposed work will provide the first investigation of, and predictive models for, the attributes of locations that promote population persistence in range retreating species. The project will address fundamental questions about the dynamics of species' ranges under climate change, as well as producing results of considerable practical value for policy makers. It will open up a new avenue of research on understanding the impacts of climate change on biodiversity, and provide a concrete body of scientific evidence to inform the debate on developing effective conservation strategies under climate change.