Laboratorio de Macroecología Evolutiva, Red de Biología Evolutiva, Instituto de Ecología, A.C., El Haya, 91070 Xalapa, Veracruz, Mexico;
Research Unit 5174, Laboratoire Evolution et Diversité Biologique, CNRS, Institut de Recherche pour le Développement, Université Paul Sabatier, F-31062 Toulouse, France.
Proc Natl Acad Sci U S A. 2019 Jul 2;116(27):13434-13439. doi: 10.1073/pnas.1902484116. Epub 2019 Jun 17.
Identifying the drivers and processes that determine globally the geographic range size of species is crucial to understanding the geographic distribution of biodiversity and further predicting the response of species to current global changes. However, these drivers and processes are still poorly understood, and no ecological explanation has emerged yet as preponderant in explaining the extent of species' geographical range. Here, we identify the main drivers of the geographic range size variation in freshwater fishes at global and biogeographic scales and determine how these drivers affect range size both directly and indirectly. We tested the main hypotheses already proposed to explain range size variation, using geographic ranges of 8,147 strictly freshwater fish species (i.e., 63% of all known species). We found that, contrary to terrestrial organisms, for which climate and topography seem preponderant in determining species' range size, the geographic range sizes of freshwater fishes are mostly explained by the species' position within the river network, and by the historical connection among river basins during Quaternary low-sea-level periods. Large-ranged fish species inhabit preferentially lowland areas of river basins, where hydrological connectivity is the highest, and also are found in river basins that were historically connected. The disproportionately high explanatory power of these two drivers suggests that connectivity is the key component of riverine fish geographic range sizes, independent of any other potential driver, and indicates that the accelerated rates in river fragmentation might strongly affect fish species distribution and freshwater biodiversity.
确定决定物种全球地理分布范围大小的驱动因素和过程对于理解生物多样性的地理分布以及进一步预测物种对当前全球变化的反应至关重要。然而，这些驱动因素和过程仍然知之甚少，并且还没有出现一种生态学解释能够主导解释物种地理分布范围的大小。在这里，我们确定了淡水鱼类在全球和生物地理尺度上地理分布范围大小变化的主要驱动因素，并确定了这些驱动因素如何直接和间接影响分布范围的大小。我们使用了 8147 种严格的淡水鱼类物种（即所有已知物种的 63%）的地理分布范围来检验已经提出的解释分布范围变化的主要假设。我们发现，与气候和地形似乎主导陆地生物物种分布范围大小的情况相反，淡水鱼类的地理分布范围大小主要由物种在河流网络中的位置以及第四纪低海平面时期流域之间的历史连接决定。分布范围较大的鱼类物种优先栖息在流域的低地地区，那里的水文连通性最高，而且也存在于历史上有联系的流域中。这两个驱动因素的解释力非常高，这表明连通性是河流鱼类地理分布范围大小的关键组成部分，独立于任何其他潜在的驱动因素，并表明河流破碎化的加速速度可能会强烈影响鱼类物种的分布和淡水生物多样性。
