Rex Michael A, McClain Craig R, Johnson Nicholas A, Etter Ron J, Allen John A, Bouchet Philippe, Warén Anders
Department of Biology, University of Massachusetts, Boston, Massachusetts 02125, USA.
Am Nat. 2005 Feb;165(2):163-78. doi: 10.1086/427226. Epub 2004 Dec 22.
Bathymetric gradients of biodiversity in the deep-sea benthos constitute a major class of large-scale biogeographic phenomena. They are typically portrayed and interpreted as variation in alpha diversity (the number of species recovered in individual samples) along depth transects. Here, we examine the depth ranges of deep-sea gastropods and bivalves in the eastern and western North Atlantic. This approach shows that the abyssal molluscan fauna largely represents deeper range extensions for a subset of bathyal species. Most abyssal species have larval dispersal, and adults live at densities that appear to be too low for successful reproduction. These patterns suggest a new explanation for abyssal biodiversity. For many species, bathyal and abyssal populations may form a source-sink system in which abyssal populations are regulated by a balance between chronic extinction arising from vulnerabilities to Allee effects and immigration from bathyal sources. An increased significance of source-sink dynamics with depth may be driven by the exponential decrease in organic carbon flux to the benthos with increasing depth and distance from productive coastal systems. The abyss, which is the largest marine benthic environment, may afford more limited ecological and evolutionary opportunity than the bathyal zone.
深海底栖生物多样性的测深梯度构成了一类主要的大规模生物地理现象。它们通常被描绘和解释为沿深度断面的α多样性（单个样本中恢复的物种数量）变化。在这里，我们研究了北大西洋东部和西部深海腹足类动物和双壳类动物的深度范围。这种方法表明，深海软体动物群在很大程度上代表了一部分深海物种更深的分布范围扩展。大多数深海物种有幼虫扩散，而成体的生活密度似乎过低，无法成功繁殖。这些模式为深海生物多样性提供了一种新的解释。对于许多物种来说，深海和深渊种群可能形成一个源 - 汇系统，其中深渊种群受到因对阿利效应敏感而导致的长期灭绝与来自深海源的迁入之间平衡的调节。随着深度增加，源 - 汇动态的重要性增加可能是由有机碳通量随着深度增加以及与高产沿海系统距离增加而呈指数下降所驱动的。深渊是最大的海洋底栖环境，与深海区相比，它可能提供的生态和进化机会更为有限。
