de Queiroz Alan
Trends Ecol Evol. 2005 Feb;20(2):68-73. doi: 10.1016/j.tree.2004.11.006. Epub 2004 Nov 25.
Geographical distributions of terrestrial or freshwater taxa that are broken up by oceans can be explained by either oceanic dispersal or vicariance in the form of fragmentation of a previously contiguous landmass. The validation of plate-tectonics theory provided a global vicariance mechanism and, along with cladistic arguments for the primacy of vicariance, helped create a view of oceanic dispersal as a rare phenomenon and an explanation of last resort. Here, I describe recent work that suggests that the importance of oceanic dispersal has been strongly underestimated. In particular, molecular dating of lineage divergences favors oceanic dispersal over tectonic vicariance as an explanation for disjunct distributions in a wide variety of taxa, from frogs to beetles to baobab trees. Other evidence, such as substantial gene flow among island populations of Anolis lizards, also indicates unexpectedly high frequencies of oceanic dispersal. The resurrection of oceanic dispersal is the most striking aspect of a major shift in historical biogeography toward a more even balance between vicariance and dispersal explanations. This new view implies that biotas are more dynamic and have more recent origins than had been thought previously. A high frequency of dispersal also suggests that a fundamental methodological assumption of many biogeographical studies--that vicariance is a priori a more probable explanation than dispersal--needs to be re-evaluated and perhaps discarded.
被海洋分隔的陆地或淡水生物分类群的地理分布，可以通过海洋扩散或以前连续的陆地块体破碎形式的隔离分化来解释。板块构造理论的验证提供了一种全球隔离分化机制，并且与支持隔离分化首要地位的分支系统学观点一起，有助于形成一种将海洋扩散视为罕见现象且是最后的解释手段的观点。在此，我描述了最近的研究工作，这些工作表明海洋扩散的重要性被严重低估了。特别是，谱系分化的分子定年法更倾向于用海洋扩散而非构造隔离分化来解释从青蛙到甲虫再到猴面包树等各种各样生物分类群的间断分布。其他证据，比如安乐蜥岛屿种群间大量的基因流动，也表明海洋扩散的频率出乎意料地高。海洋扩散的复兴是历史生物地理学重大转变中最引人注目的方面，这一转变使隔离分化和扩散解释之间达到了更平衡的状态。这种新观点意味着生物群落比之前认为的更具动态性且起源更近。高频率的扩散还表明，许多生物地理学研究的一个基本方法假设——即隔离分化在本质上比扩散更有可能是一种解释——需要重新评估，甚至可能被摒弃。
