東南亞主要島嶼繁殖鳥類相的生物地理界線

Biogeographic Boundaries of Breeding Avifauna between Major Islands in East Asia

生物地理區的研究歷史已超過一百五十年，其中又以東亞島嶼之間的生物地理界線為最主要的研究焦點。本研究針對北起庫頁島，南至小巽他群島，橫跨古北區、東洋區、澳洲區的主要島嶼，進行整合統計檢測，根據區域中所有陸域繁殖鳥種分布範圍，計算島嶼間的辛普森相異度指標，進行集群分析及非度量多維尺度排序來劃分生物地理界線。結果顯示，小巽他群島繁殖鳥類相與東洋區較為相似，而非澳洲區，因此東洋區與澳洲區的合理生物地理界線應落於小巽他群島與摩鹿加群島間海峽，其餘分界與華萊士線相同。巴拉望繁殖鳥類相與菲律賓較為相似，而非婆羅洲，巴拉望與婆羅洲的繁殖鳥類相應屬於不同的生物地理次區。古北區與東洋區的界線為臺灣與菲律賓間海峽。琉球群島、北海道的繁殖鳥類相，分別與九州、本州等生物地理次區的繁殖鳥類相差異較大。這些分界可能導因於更新世海水面昇降形成的陸橋與海峽障礙，造成現今界線兩側的繁殖鳥類相的差異。在以全球及大陸為主要研究範圍的生物地理研究中，本研究聚焦島嶼間的生物地理界線，提供一個以島嶼為主體的生物地理觀點。

Biogeographic regions have attracted study interest for more than 150 years, and one of the major focuses has been biogeographic boundaries between islands in East Asia. This study is a statistical examination of the breeding avifauna on major islands in East Asia, from Sakhalin to the Lesser Sunda Islands, across the Palearctic, the Oriental, and the Australian regions. Based on the breeding distribution of all terrestrial bird species, we calculated Simpson dissimilarity index between islands and delineated the boundaries of the biogeographic regions, using cluster analysis and Non-metric Multi-Dimension Scaling. Results show that the breeding avifauna on the Lesser Sunda Islands had strong Oriental affinities rather than Australian ones. Thus, the Lesser Sunda Islands should be classified into the Oriental region. The biogeographic boundary between the Oriental and the Australian regions should fall between the Lesser Sunda Islands and Maluku, and the remaining part follows Wallace’s Line. In addition, the breeding avifauna on Palawan was distinct from that on Borneo, not the Philippines. This suggests that Palawan and Borneo should be classified into different biogeographic regions. Moreover, the biogeographic boundary between the Palearctic and the Oriental regions should be located along the strait between Taiwan and the Philippines. The Ryukyu Islands and Kyushu may should be classified into different biogeographic sub-regions, as well as Hokkaido and Honshu. These biogeographic boundaries were related to the difference between the breeding avifauna on the islands, which may have been caused by land bridges and strait barriers resulting from sea level changes during the Pleistocene. While relevant studies have focused on faunal differences on continents, this study examined the biogeographic boundaries between islands and provides a unique viewpoint to the delineation of biogeographic regions.