1. To test hypotheses concerning the applicability of the Rapoport effect (RE: “species that occur at higher latitudes tend to have greater geographical range‐size than species which have ranges limited to latitudes closer to the equator”) to aquatic macrophytes at global scale, we analysed the world latitudinal distribution and range‐size of 1,083 vascular aquatic macrophyte species, from 91 genera in 11 families. We targeted macrophyte families strongly associated with inland aquatic habitats (i.e. with a zero, or only very low, proportion of constituent species which occur also in non‐aquatic habitats), and which are distributed across a substantial latitudinal gradient, a necessary condition to test our hypotheses.
2. The macrophyte species present in these families include plants from all the normally accepted life form‐defined functional groups of macrophytes, namely submerged, free‐floating, floating‐leaf rooted and emergent species, and represent the three major vascular taxonomic groups occurring as aquatic macrophytes (ferns/fern allies, monocots, and dicots). For the analysis, we used both latitude‐only and areal measures of macrophyte species geographic range‐size, within a 10 × 10° (latitude × longitude) grid of 238 grid cells, covering the six world ecozones (Palaearctic, Orient, Australasia, Nearctic, Neotropics, Afrotropics) that primarily contain inland freshwater and brackish macrophyte habitats.
3. The results provide new insight into the relationships between global range‐size of macrophytes, latitude, and other potential spatio‐environmental and anthropogenic drivers acting upon these plants at world scale. In particular, the outcomes indicated that: (1) the range‐size versus latitude distribution of macrophytes shows evidence of a strong RE influence, with significantly greater species range‐size at higher latitudes; and (2) the β‐diversity pattern of species distribution along this latitudinal gradient is poorly explained by nestedness organisation, and species turnover is a more likely explanation of the observed changes in species distribution with latitude.
4. Spatio‐environmental and anthropogenic variables other than latitude may also influence the observed global geographical pattern of macrophyte range‐size, although their importance as predictors varies between individual families. Extent of agricultural land use, altitude, and historic (post‐Quaternary) climate change velocity were all significant predictor variables for some families. However, interestingly, neither the area of land nor the area of waterbody present per grid cell were major influences on macrophyte range‐size distribution.
5. Our finding of evidence for an RE, acting at global scale in aquatic macrophytes, contributes to increasing the generality of conclusions so far reached about the large‐scale factors that drive patterns of species range‐size at global scale. The study also provides a baseline for future macroecological work on aquatic plants, and potentially other freshwater organisms, particularly in the context of predicting how the world ranges of freshwater biota will respond to ongoing global environmental change.

中文翻译：

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水生植物种的全球范围大小的纬度变化显示出Rapoport效应的证据

1. 为了检验有关拉坡波特效应的适用性的假设（RE：“在较高纬度地区发生的物种比在有限纬度范围内接近赤道的物种倾向于具有更大的地理范围大小”），我们在全球范围内对水生植物进行了研究。分析了来自11个科的91属的1,083种维管束水生植物的世界纬度分布和范围大小。我们的目标是与内陆水生栖息地密切相关的大型植物科（即零比例或仅极低比例的非水生生境中也存在的组成物种），并且分布在较大的纬度梯度上，这是测试的必要条件我们的假设。
2. 这些科目中存在的大型植物物种包括来自所有通常公认的生命形式定义的大型植物功能组的植物，即淹没，自由漂浮，浮叶生根和出苗物种，代表了作为水生大型植物而出现的三个主要的血管分类学类别。 （蕨类/蕨类同盟，单子叶植物和双子叶植物）。为了进行分析，我们在238个网格单元的10×10°（纬度×经度）网格内，对大型植物物种地理范围大小进行了仅纬度和面积测量，涵盖了六个世界生态区（古北，东方，大洋洲， （近热带，新热带，非热带），主要包含内陆淡水和微咸的大型植物栖息地。
3. 结果为全球范围内大型植物的全球范围大小，纬度与其他潜在的时空环境和人为驱动因素之间的关系提供了新的见解。具体而言，结果表明：（1）大型植物的范围大小与纬度分布显示出强烈的可再生能源影响的证据，较高纬度的物种范围大小明显更大；（2）巢状组织很难很好地解释沿这个纬度梯度的物种分布的β-多样性模式，而物种周转更可能解释了随纬度观察到的物种分布变化。
4. 尽管纬度以外的时空环境和人为因素也可能影响所观察到的大型植物范围大小的全球地理格局，尽管它们作为预报因子的重要性在各个家庭之间有所不同。对于某些家庭来说，农业土地利用的程度，海拔高度和历史（第四纪后）气候变化速度都是重要的预测变量。然而，有趣的是，每个网格单元的土地面积或水体面积都不会对大型植物的范围大小分布产生重大影响。
5. 我们发现的稀土元素在水生植物中在全球范围内起作用的证据，有助于增加迄今为止得出的关于驱动全球范围内物种规模格局的大规模因素的结论的普遍性。该研究还为将来在水生植物以及潜在的其他淡水生物上的宏观生态工作提供了基线，尤其是在预测世界范围内的淡水生物群将如何应对持续的全球环境变化方面。