Effects of climate change on a reptile community in arid Australia

在过去的几十年里，全球平均温度异常升高，随着极端事件频率的增加，降水变得更加多变。强有力的证据已经表明，气候变化对生物多样性有相当大的影响。然而，由于特定的生活史特征和全球气候变化不均匀，物种的反应不同。因此，不同生态系统之间的反应也不同。虽然大多数研究集中在温带地区和热带系统，但对拥有高度和主要地方性陆地生物多样性的炎热干旱生态系统知之甚少。在炎热的沙漠中，脊椎动物的多样性以爬行动物为代表。和任何变温动物一样，爬行动物的新陈代谢和生物学与外界温度密切相关，这使它们对气候变化特别敏感。除了与温度和降水变化相关的直接影响外，植被覆盖和捕食者也是爬行动物种群的重要驱动因素，但在很大程度上文献不足。通过对澳大利亚东部干旱区东部边缘蜥蜴群落的长期监测研究，我们将量化近30年来澳大利亚东部干旱区蜥蜴生态与气候的各种直接和间接影响（通过植被和捕食者）之间的关系。然后，我们将在现有的驱动方案下预测未来的人口轨迹。澳大利亚的干旱地区特别适合研究气候变化的影响，因为该地区对全球气候变化和厄尔尼诺-南方涛动（ENSO）引起的气候相关变化特别敏感，后者导致干旱（厄尔尼诺）和洪水（拉尼娜）。分析将包括估计蜥蜴种群规模、人口统计参数和蜥蜴群落组成趋势与温度、当地降雨、捕食者丰度、植被覆盖和ENSO驱动的极端事件变化的关系。我们将进一步研究人口统计参数如何与活动的热限制联系起来，这一机制是当前预测气候对爬行动物全球影响的模型的关键假设。最后，我们将利用基于过程的矩阵模型中最先进的方法来整合这种机制理解，以预测气候变化对干旱澳大利亚蜥蜴的未来影响。

Within the past decades, global mean temperature has exceptionally increased and precipitation became more variable with extreme events increasing in frequency. Strong evidences already suggest that climate change has considerable impact on biodiversity. However, species respond differently due to specific life-history traits and because climate change is not uniform across the globe. Thus, responses also differ between ecosystems. While most studies are focussing on temperate regions and tropical systems, little is known in hot arid ecosystems, which harbour a high and mainly endemic terrestrial biological diversity. The largest part of vertebrate diversity in hot deserts is represented by reptiles. As any ectotherms, reptile metabolism and biology are tightly linked to external temperature, making them particularly sensitive to climate change. Beside direct effects associated to changes in temperature and precipitation, vegetation cover and predators are important but largely under-documented drivers of reptile populations. Taking advantage of a long-term monitoring study on a lizard community in the eastern margin of the arid zone of Australia, we will quantify the relationship between lizard ecology and different direct and indirect effects (via vegetation and predators) of climate in the arid zone of Eastern Australia during the last 30 years. We will then project future population trajectories under existing driver scenarios. Australias arid zones are particularly suitable to study the effects of climate change since this region is particularly sensitive to climate-related changes via global climate change and El Nino Southern Oscillation (ENSO), the latter resulting in droughts (El Nino) and floods (La Nina). Analyses will comprise estimating the relationships of trends in lizard population sizes, demographic parameters, and trends of lizard community composition with changes in temperature, local rainfall, predator abundance, vegetation cover, and ENSO driven extreme events. We will further investigate how demographic parameters are linked to thermal restrictions of activity, a mechanism that is a key assumption of current models predicting global effects of climate on reptiles. We will finally integrate such mechanistic understanding using state of the art approaches in process-based matrix modelling to project the future impacts of climate change on lizards in arid Australia.