Museum of Zoology & Department of Ecology and Evolutionary Biology, University of Michigan, 2032 Biological Sciences Building, Ann Arbor, MI, 48109, USA.
Biol Rev Camb Philos Soc. 2022 Dec;97(6):2090-2105. doi: 10.1111/brv.12884. Epub 2022 Jul 28.
The latitudinal diversity gradient (LDG) is frequently described as the most dramatic biodiversity pattern on Earth, yet ecologists and biogeographers have failed to reach consensus on its primary cause. A key problem in explaining the LDG involves collinearity between multiple factors that are predicted to affect species richness in the same direction. In terrestrial systems, energy input, geographic area, and evolutionary time for species accumulation tend to covary positively with species richness at the largest spatial scales, such that their individual contributions to the LDG are confounded in global analyses. I review three diversity patterns from marine and freshwater systems that break this collinearity and which may thus provide stronger tests of the influence of time on global richness gradients. Specifically, I contrast biodiversity patterns along oceanic depth gradients, in geologically young versus ancient lakes, and in the north versus south polar marine biomes. I focus primarily on fishes due to greater data availability but synthesize patterns for invertebrates where possible. I find that regional-to-global species richness generally declines with depth in the oceans, despite the great age and stability of the deep-sea biome. Geologically ancient lakes generally do not contain more species than young lakes, and the Antarctic marine biome is not appreciably more species rich than the much younger Arctic marine biome. However, endemism is consistently higher in older systems. Patterns for invertebrate groups are less clear than for fishes and reflect a critical need for primary biodiversity data. In summary, the available data suggest that species richness is either decoupled from or only weakly related to the amount of time for diversification. These results suggest that energy, productivity, or geographic area are the primary drivers of large-scale diversity gradients. To the extent that marine and terrestrial diversity gradients result from similar processes, these examples provide evidence against a primary role for evolutionary time as the cause of the LDG.
纬度多样性梯度（LDG）通常被描述为地球上最显著的生物多样性模式，但生态学家和生物地理学家未能就其主要成因达成共识。解释 LDG 的一个关键问题涉及到多个因素之间的共线性，这些因素被预测会以相同的方向影响物种丰富度。在陆地系统中，能量输入、地理区域和物种积累的进化时间往往与最大空间尺度上的物种丰富度呈正相关，因此它们对 LDG 的单独贡献在全球分析中是混淆的。我回顾了海洋和淡水系统中的三种多样性模式，这些模式打破了这种共线性，因此可能为时间对全球丰富度梯度的影响提供更强的检验。具体来说，我对比了海洋深度梯度、地质年轻与古老湖泊以及南北极海洋生物群系中的生物多样性模式。我主要关注鱼类，因为数据可用性更大，但在可能的情况下也综合了无脊椎动物的模式。我发现，尽管深海生物群系的年龄很大且稳定，但区域到全球的物种丰富度通常随海洋深度的增加而下降。地质古老的湖泊通常没有比年轻的湖泊拥有更多的物种，而且南极海洋生物群系的物种丰富度并不比年轻得多的北极海洋生物群系明显更高。然而，特有种的比例在较老的系统中始终更高。无脊椎动物群体的模式不如鱼类清晰，反映出对主要生物多样性数据的迫切需求。总之，现有数据表明，物种丰富度要么与多样化的时间量脱钩，要么只有微弱的关系。这些结果表明，能量、生产力或地理区域是大规模多样性梯度的主要驱动因素。在海洋和陆地多样性梯度由相似过程导致的程度上，这些例子为进化时间不是 LDG 主要成因提供了证据。
