巽他大陸的西部（馬來西亞半島和蘇門答臘島）和東部（婆羅洲）生物地理格局具有顯著差異。這些差異一直是研究的熱點,。有人認(rèn)為這是由于冰川時期干燥熱帶稀樹草原走廊形成的擴(kuò)散屏障所造成的。然而這些熱帶稀樹草原條件持續(xù)時間短,，可能不是這些生物地理格局差異的唯一原因,。另一種解釋可能與巽他大陸中央的沙質(zhì)土壤有關(guān)。
中科院西雙版納熱帶植物園植物地理創(chuàng)新研究組Ferry Slik研究員等人基于馬來西亞半島,、蘇門答臘島和婆羅洲的111個樹木物種目錄對植物區(qū)系進(jìn)行聚類分析,，從而驗證這兩個假說。然后,，他們把那些在巽他大陸中央和周邊都有分布的指示屬以及僅在某些區(qū)域的屬進(jìn)行區(qū)分,，用這些屬來檢驗它們對干旱和沙質(zhì)土壤的耐受性的差異。最終他們發(fā)現(xiàn)11個不同區(qū)系聚類,，婆羅洲有10個,，蘇門答臘有5個，馬來西亞半島有3個,。那些跨越巽他大陸分布的指示分類群比只分布在巽他大陸東部,、西部或者中央的分類群具有顯著高的沙質(zhì)土壤的耐受性。而對干旱耐受性的檢測,，則沒有發(fā)現(xiàn)這種格局的存在,。基于這些結(jié)果,，他們推斷巽他大陸中央的沙質(zhì)海床土壤是擴(kuò)散屏障,。不過，他們無法證實熱帶稀樹草原走廊的存在,。
這一發(fā)現(xiàn)解釋了巽他大陸植物和動物分布生物地理格局的成因,，包括早期人類可能的遷移路線在內(nèi)的一系列問題都需要重新評估。這也是世界上首次提出土壤是造成巽他大陸不同地區(qū)生物地理格局差異的原因,。
相關(guān)研究成果已經(jīng)發(fā)表在國際著名雜志美國《國家科學(xué)院院刊》（PNAS）上,。(生物谷 Bioon.com)
doi:10.1073/pnas.1103353108
PMC:
PMID:
Soils on exposed Sunda Shelf shaped biogeographic patterns in the equatorial forests of Southeast Asia
Slik, J. W. Ferry; Aiba, Shin-Ichiro; Bastian, Meredith; Brearley, Francis Q.; Cannon, Charles H.; Eichhorn, Karl A. O.; Fredriksson, Gabriella; Kartawinata, Kuswata; Laumonier, Yves; Mansor, Asyraf; Marjokorpi, Antti; Meijaard, Erik; Morley, Robert J.; Nagamasu, Hidetoshi; Nilus, Reuben; Nurtjahya, Eddy; Payne, John; Permana, Andrea; Poulsen, Axel D.; Raes, Niels; Riswan, Soedarsono; van Schaik, Carel P.; Sheil, Douglas; Sidiyasa, Kade; Suzuki, Eizi; van Valkenburg, Johan L. C. H.; Webb, Campbe
The marked biogeographic difference between western (Malay Peninsula and Sumatra) and eastern (Borneo) Sundaland is surprisinggiven the long time that these areas have formed a single landmass. A dispersal barrier in the form of a dry savanna corridorduring glacial maxima has been proposed to explain this disparity. However, the short duration of these dry savanna conditionsmake it an unlikely sole cause for the biogeographic pattern. An additional explanation might be related to the coarse sandysoils of central Sundaland. To test these two nonexclusive hypotheses, we performed a floristic cluster analysis based on111 tree inventories from Peninsular Malaysia, Sumatra, and Borneo. We then identified the indicator genera for clusters thatcrossed the central Sundaland biogeographic boundary and those that did not cross and tested whether drought and coarse-soiltolerance of the indicator genera differed between them. We found 11 terminal floristic clusters, 10 occurring in Borneo,5 in Sumatra, and 3 in Peninsular Malaysia. Indicator taxa of clusters that occurred across Sundaland had significantly highercoarse-soil tolerance than did those from clusters that occurred east or west of central Sundaland. For drought tolerance,no such pattern was detected. These results strongly suggest that exposed sandy sea-bed soils acted as a dispersal barrierin central Sundaland. However, we could not confirm the presence of a savanna corridor. This finding makes it clear that proposedbiogeographic explanations for plant and animal distributions within Sundaland, including possible migration routes for earlyhumans, need to be reevaluated.
