It is widely accepted that sea level changes intermittently inundated the Sunda Shelf throughout the Pleistocene, separating Java, Sumatra and Borneo from the Malay Peninsula and from each other. On this basis, the dynamics of the biodiversity hotspot of Sundaland is consistently regarded as solely contingent on glacial sea level oscillations, with interglacial highstands creating intermittent dispersal barriers between disjunct landmasses. However, recent findings on the geomorphology of the currently submerged Sunda shelf suggest that it subsided during the Pleistocene and that, over the Late Pliocene and Quaternary, is was never submerged prior to Marine Isotope Stage 11 (MIS 11, 400 ka). This would have enabled the dispersal of terrestrial organisms regardless of sea level variations until 400 ka and hampered movements thereafter, at least during interglacial periods. Existing phylogeographic data for terrestrial organisms conform to this scenario: available divergence time estimates reveal an 8‐ to 9‐fold increase in the rate of vicariance between landmasses of Sundaland after 400 ka, corresponding to the onset of episodic flooding of the Sunda shelf. These results highlight how reconsidering the paleogeographic setting of Sundaland challenges understanding the mechanisms generating Southeast Asian biodiversity.

中文翻译：

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桑达兰沉陷的证据需要重新审查其生物地理

海平面的变化断断续续地淹没了整个更新世的Sun他架，这使爪哇，苏门答腊和婆罗洲与马来半岛相互分隔开来，这已被广泛接受。在此基础上，始终将桑达兰生物多样性热点地区的动态视作仅取决于冰川海平面的振荡，而冰川间的高水位则在各不相干的陆块之间形成了间歇性的扩散障碍。但是，最近对当前沉没的Sun他陆架地貌的发现表明，它在更新世期间已经消沉，在上新世晚期和第四纪之前，从未在海洋同位素第11期（MIS 11，400 ka）之前被淹没。这样一来，无论海平面如何变化，直到400 ka以后，陆生生物都能散布开来，此后移动受到阻碍，至少在间冰期。现有的陆生生物系统地理学数据都符合这种情况：可用的发散时间估计值显示，在400 ka之后，da他岛陆块之间的变异速率增加了8到9倍，这对应于da他陆架的爆发性洪水。这些结果凸显了如何重新考虑桑达兰州的古地理环境对理解东南亚生物多样性产生机理的挑战。