Steinbauer Manuel J, Irl Severin D H, González-Mancebo Juana María, Breiner Frank T, Hernández-Hernández Raquel, Hopfenmüller Sebastian, Kidane Yohannes, Jentsch Anke, Beierkuhnlein Carl
Department of Biogeography Bay CEER University of Bayreuth Bayreuth Germany; Section Ecoinformatics & Biodiversity Department of Bioscience Aarhus University Aarhus Denmark.
Department of Biogeography BayCEER University of Bayreuth Bayreuth Germany.
Ecol Evol. 2016 Dec 27;7(2):771-779. doi: 10.1002/ece3.2640. eCollection 2017 Jan.
Ecosystems that provide environmental opportunities but are poor in species and functional richness generally support speciation as well as invasion processes. These processes are expected not to be equally effective along elevational gradients due to specific ecological, spatial, and anthropogenic filters, thus controlling the dispersal and establishment of species. Here, we investigate speciation and invasion processes along elevational gradients. We assess the vascular plant species richness as well as the number and percentage of endemic species and non-native species systematically along three elevational gradients covering large parts of the climatic range of La Palma, Canary Islands. Species richness was negatively correlated with elevation, while the percentage of Canary endemic species showed a positive relationship. However, the percentage of Canary-Madeira endemics did not show a relationship with elevation. Non-native species richness (indicating invasion) peaked at 500 m elevation and showed a consistent decline until about 1,200 m elevation. Above that limit, no non-native species were present in the studied elevational gradients. Ecological, anthropogenic, and spatial filters control richness, diversification, and invasion with elevation. With increase in elevation, richness decreases due to species-area relationships. Ecological limitations of native ruderal species related to anthropogenic pressure are in line with the absence of non-native species from high elevations indicating directional ecological filtering. Increase in ecological isolation with elevation drives diversification and thus increased percentages of Canary endemics. The best preserved eastern transect, including mature laurel forests, is an exception. The high percentage of Canary-Madeira endemics indicates the cloud forest's environmental uniqueness-and thus ecological isolation-beyond the Macaronesian islands.
提供环境机遇但物种和功能丰富度较低的生态系统通常既支持物种形成过程，也支持入侵过程。由于特定的生态、空间和人为过滤因素，预计这些过程在海拔梯度上的效果并不相同，从而控制着物种的扩散和定居。在此，我们研究沿海拔梯度的物种形成和入侵过程。我们系统地评估了加那利群岛拉帕尔马岛大部分气候范围内的三个海拔梯度上的维管植物物种丰富度，以及特有物种和非本地物种的数量及百分比。物种丰富度与海拔呈负相关，而加那利特有物种的百分比呈正相关。然而，加那利 - 马德拉特有物种的百分比与海拔并无关联。非本地物种丰富度（表明入侵情况）在海拔500米处达到峰值，并在约1200米海拔之前持续下降。超过该界限，在所研究的海拔梯度中未发现非本地物种。生态、人为和空间过滤因素随着海拔控制着丰富度、多样化和入侵情况。随着海拔升高，由于物种 - 面积关系，丰富度降低。与人为压力相关的本地杂草物种的生态限制与高海拔地区不存在非本地物种相符，这表明存在定向生态过滤。随着海拔升高生态隔离增加推动了多样化，从而使加那利特有物种的百分比增加。保存最完好的东部样带，包括成熟的月桂树林，是个例外。加那利 - 马德拉特有物种的高百分比表明云雾森林除了马卡罗尼西亚群岛之外的环境独特性——进而生态隔离。
