Shipley Benjamin R, McGuire Jenny L
School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA.
School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA.
Glob Chang Biol. 2023 May;29(9):2421-2435. doi: 10.1111/gcb.16628. Epub 2023 Feb 16.
Endemic species and species with small ranges are ecologically and evolutionarily distinct and are vulnerable to extinction. Determining which abiotic and biotic factors structure patterns of endemism on continents can advance our understanding of global biogeographic processes, but spatial patterns of mammalian endemism have not yet been effectively predicted and reconstructed. Using novel null model techniques, we reconstruct trends in mammalian endemism and describe the isolated and combined effects of physiographic, ecological, and evolutionary factors on endemism. We calculated weighted endemism for global continental ecoregions and compared the spatial distribution of endemism to niche-based, geographic null models of endemism. These null models distribute species randomly across continents, simulating their range sizes from their degree of climatic specialization. They isolate the effects of physiography (topography and climate) and species richness on endemism. We then ran linear and structural models to determine how topography and historical climate stability influence endemism. The highest rates of mammalian endemism were found in topographically rough, climatically stable ecoregions with many species. The null model that isolated physiography did not closely approximate the observed distribution of endemism (r = .09), whereas the null model that incorporated both physiography and species richness did (r = .59). The linear models demonstrate that topography and climatic stability both influenced endemism values, but that average climatic niche breadth was not highly correlated with endemism. Climate stability and topography both influence weighted endemism in mammals, but the spatial distribution of mammalian endemism is driven by a combination of physiography and species richness. Despite its relationship to individual range size, average climate niche breadth has only a weak influence on endemism. The results highlight the importance of historical biogeographic processes (e.g. centers of speciation) and geography in driving endemism patterns, and disentangle the mechanisms structuring species ranges worldwide.
特有物种和分布范围狭小的物种在生态和进化上具有独特性，并且容易灭绝。确定哪些非生物和生物因素构成了各大洲特有现象的格局，有助于我们深入理解全球生物地理过程，但哺乳动物特有现象的空间格局尚未得到有效预测和重建。利用新颖的零模型技术，我们重建了哺乳动物特有现象的趋势，并描述了地形、生态和进化因素对特有现象的单独和综合影响。我们计算了全球大陆生态区的加权特有性，并将特有性的空间分布与基于生态位的特有性地理零模型进行比较。这些零模型将物种随机分布在各大洲，根据其气候特化程度模拟其分布范围大小。它们分离了地形（地形和气候）和物种丰富度对特有性的影响。然后，我们运行线性模型和结构模型，以确定地形和历史气候稳定性如何影响特有性。在地形崎岖、气候稳定且物种丰富的生态区，发现了最高的哺乳动物特有率。分离地形的零模型与观察到的特有性分布不太接近（r = 0.09），而纳入地形和物种丰富度的零模型则较为接近（r = 0.59）。线性模型表明，地形和气候稳定性都影响特有性值，但平均气候生态位宽度与特有性的相关性不高。气候稳定性和地形都影响哺乳动物的加权特有性，但哺乳动物特有性的空间分布是由地形和物种丰富度共同驱动的。尽管平均气候生态位宽度与个体分布范围大小有关，但其对特有性的影响较弱。研究结果凸显了历史生物地理过程（如物种形成中心）和地理因素在驱动特有现象格局方面的重要性，并厘清了全球范围内构建物种分布范围的机制。
