Thormann Birthe, Ahrens Dirk, Espinosa Carlos Iván, Armijos Diego Marín, Wagner Thomas, Wägele Johann W, Peters Marcell K
Zoological Research Museum Alexander Koenig, Adenauerallee 160, 53113, Bonn, Germany.
Departamento de Ciencias Naturales, Universidad Técnica Particular de Loja, Loja, Ecuador.
Oecologia. 2018 May;187(1):181-189. doi: 10.1007/s00442-018-4108-4. Epub 2018 Mar 9.
Elevational diversity gradients are typically studied without considering the complex small-scale topography of large mountains, which generates habitats of strongly different environmental conditions within the same elevational zones. Here we analyzed the importance of small-scale topography for elevational diversity patterns of hyperdiverse tropical leaf beetles (Coleoptera: Chrysomelidae). We compared patterns of elevational diversity and species composition of beetles in two types of forests (on mountain ridges and in valleys) and analyzed whether differences in the rate of species turnover among forest habitats lead to shifts in patterns of elevational diversity when scaling up from the local study site to the elevational belt level. We sampled beetle assemblages at 36 sites in the Podocarpus National Park, Ecuador, which were equally distributed over two forest habitats and three elevational levels. DNA barcoding and Poisson tree processes modelling were used to delimitate putative species. On average, local leaf beetle diversity showed a clear hump-shaped pattern. However, only diversity in forests on mountain ridges peaked at mid-elevation, while beetle diversity in valleys was similarly high at low- and mid-elevation and only declined at highest elevations. A higher turnover of species assemblages at lower than at mid-elevations caused a shift from a hump-shaped diversity pattern found at the local level to a low-elevation plateau pattern (with similar species numbers at low and mid-elevation) at the elevational belt level. Our study reveals an important role of small-scale topography and spatial scale for the inference on gradients of elevational species diversity.
海拔多样性梯度的研究通常未考虑大型山脉复杂的小尺度地形，这种地形会在同一海拔带内形成环境条件差异极大的栖息地。在此，我们分析了小尺度地形对超多样的热带叶甲（鞘翅目：叶甲科）海拔多样性模式的重要性。我们比较了两种森林类型（山脊和山谷）中叶甲的海拔多样性模式和物种组成，并分析了从局部研究地点扩展到海拔带水平时，森林栖息地间物种更替率的差异是否会导致海拔多样性模式的转变。我们在厄瓜多尔波多黎各国家公园的36个地点采集了叶甲群落样本，这些地点在两种森林栖息地和三个海拔水平上均匀分布。利用DNA条形码和泊松树过程建模来界定假定物种。平均而言，当地叶甲多样性呈现出明显的驼峰状模式。然而，只有山脊森林中的多样性在中海拔达到峰值，而山谷中的叶甲多样性在低海拔和中海拔同样较高，仅在最高海拔处下降。低海拔处物种组合的周转率高于中海拔，这导致了从局部水平发现的驼峰状多样性模式转变为海拔带水平的低海拔高原模式（低海拔和中海拔物种数量相似）。我们的研究揭示了小尺度地形和空间尺度在推断海拔物种多样性梯度方面的重要作用。
