Roy Kaustuv, Goldberg Emma E
Section of Ecology, Behavior and Evolution, University of California San Diego, La Jolla, California 92093, USA.
Am Nat. 2007 Aug;170 Suppl 2:S71-85. doi: 10.1086/519403.
Species diversity gradients seen today are, to a large degree, a product of history. Spatially nonrandom originations, extinctions, and changes in geographic distributions can create gradients in species and higher-taxon richness, but the relative roles of each of these processes remain poorly documented. Existing explanations of diversity gradients have tended to focus on either macroevolutionary or biogeographic processes; integrative models that include both are largely lacking. We used simple models that incorporate origination and extinction rates along with dispersal of taxa between regions to show that dispersal not only affects regional richness patterns but also has a strong influence on the average age of taxa present in a region. Failure to take into account the effects of dispersal can, in principle, lead to biased estimates of diversification rates and potentially wrong conclusions regarding processes driving latitudinal and other gradients in diversity. Thus, it is critical to include the effects of dispersal when formulating and testing hypotheses about the causes of large-scale gradients in diversity. Finally, the model results, in conjunction with the results of existing empirical studies, suggest that the nature of macroevolutionary and biogeographic processes may differ between terrestrial and marine diversity gradients.
如今观察到的物种多样性梯度在很大程度上是历史的产物。空间上非随机的物种起源、灭绝以及地理分布的变化能够产生物种和更高分类单元丰富度的梯度，但这些过程各自的相对作用仍缺乏充分记录。现有的对多样性梯度的解释往往侧重于宏观进化或生物地理过程；很大程度上缺乏同时包含这两者的综合模型。我们使用了简单模型，该模型纳入了物种起源和灭绝速率以及分类单元在区域间的扩散，以表明扩散不仅影响区域丰富度模式，而且对一个区域内分类单元的平均年龄有强烈影响。原则上，不考虑扩散的影响可能导致对多样化速率的估计出现偏差，并可能得出关于驱动纬度和其他多样性梯度的过程的错误结论。因此，在制定和检验关于大规模多样性梯度成因的假设时，纳入扩散的影响至关重要。最后，模型结果与现有实证研究结果相结合，表明陆地和海洋多样性梯度之间宏观进化和生物地理过程可能存在差异。
