Geographical patterns of ferns species diversity: comparing the latitudinal and elevational gradients to disentangle climatic drivers of species diversity

为了加深对蕨类植物生物多样性地理分布的理解，我的目标是比较赤道和43°N之间东亚岛屿蕨类植物物种丰富度的纬度和海拔梯度。这两种梯度都越来越受欢迎，以便理清限制物种丰富度地理分布的众多潜在驱动因素。通过特别关注气候因素，我们将回答这样一个问题：物种从热带向温带扩散时，必须适应的主要气候限制是什么？目前还不清楚生物主要适应气候条件的哪一部分，极端气候还是气候条件的变化（如季节性）。由于它们不能单独沿着纬度梯度被解开，我将使用纬度梯度和海拔梯度的组合。向两极，气候条件的变化增加，但不是沿着海拔梯度，而极端气候变化的方式相同。因此，这种结合的方法可以解开两个因素和结论的气候限制物种丰富度的地理分布。此外，这些数据允许测试的假设，即模式的系统发育组件也反映了蕨类植物类群的进化历史，从热带温暖的高高山/温带climates.As一个结果，以前的研究，15的计划20个研究地点已经被采样的梯度的热带部分。拟议的项目将完成这一数据，以充分的纬度梯度到寒带，是第一个直接连接两个基本类型的梯度，以加深我们对蕨类植物生物多样性的地理分布的气候限制的理解。

To contribute to the increasing understanding of the geographical distribution of fern biodiversity, I aim to compare latitudinal and elevational gradients of fern species richness between the equator and 43°N on East Asian islands. Both gradients have become increasingly popular in order to disentangle the numerous potential drivers limiting the geographical distribution of species richness. By focusing specifically on the climatic component, we will answer the question: What are the main climatic constraints species have to adapt to when dispersing from the tropics to temperate climates? It is still unclear which component of climatic conditions organisms have to adapt primarily to, climatic extremes or the variation in climatic conditions (e.g. seasonality). Since they cannot be disentangled along the latitudinal gradient alone, I will use a combination of latitudinal and elevational gradients. Towards the poles, variation in climatic conditions increases but not along elevational gradients, whereas climatic extremes change the same way. This combined approach therefore allows to disentangle both factors and conclusions on the climatic constraints limiting the geographical distribution of species richness. Further these data permit to test the hypothesis that patterns of phylogenetic assemblies also reflect the evolutionary history of fern taxa in spreading from tropical-warm to high-alpine-/ temperate climates.As an outcome of a former study, 15 of the planed 20 study localities have already been sampled on the tropical part of the gradient. The proposed project will complete this data to a full latitudinal gradient up to boreal zones and is the first to directly link two basic types of gradients in order to deepen our understanding of the climatic constraints on the geographical distribuition of fern biodiversity.