利用祖先區域重建法探討東亞群島多稜攀蜥（Japalura polygonata）之歷史生物地理學

Historical biogeography of Japalura polygonata in East Asian archipelago inferred from ancestral area reconstruction methods

楊尚芳(Shang-Fang Yang)

指導教授 ： 林思民

國立臺灣師範大學/理學院/生命科學研究所/碩士(2013年)

摘要

播遷作用（dispersal）與割據作用（vicariance）是生物地理學中解釋生物分布最重要的兩種假說，而大陸型群島（continental archipelagoes）是最適合用於探討此兩種假說之島嶼類型。過去認為生物的分布大多是由割據作用所導致，然而近年來有越來越多的證據顯示，生物現今的分布其實是由播遷作用所主導。琉球群島及台灣為一列位於東亞大陸沿岸之大陸型群島，探討其上生物經歷的歷史事件將有助於我們了解大陸型群島生物相之起源。本研究旨在探討多稜攀蜥（Japalura polygonata）於琉球群島及台灣的歷史生物地理（historical biogeography），以了解影響此種生物現今分布的機制。我們使用來自27個族群的246隻個體，涵蓋了本物種所有的分布區域，並定序粒線體cytochrome b、16S ribosomal RNA、染色體Bach-1、Rag-1等一共四個片段進行親緣地理學分析。利用maximum parsimony、maximum likelihood以及Bayesian inference建構多稜攀蜥各基因型之親緣關係，並且利用BEAST、dispersal-extinction- cladogenesis model（DEC model）及statistical dispersal-vicariance analysis（S-DIVA）方法進行分析，以重建各族群之祖先地理區域及分化時間。結果顯示多稜攀蜥在各島嶼之間呈現高度的遺傳分化，總共包含八個種內的主要系群，但是與現今認定的四個亞種並不完全吻合。多稜攀蜥的共同祖先最可能起源於4.56百萬年前（上新世早期; early Pliocene）之南琉球及台灣地區，而後逐漸往北擴散至中琉球地區。DEC model分析顯示於上新世時期發生一次割據事件（3.67百萬年前）與兩次播遷事件（3.07 百萬年前），而於更新世時期發生一次割據事件及兩次播遷事件（1.32及0.47百萬年前）。而S-DIVA分析結果則與DEC model結果類似，但存在較多的播遷事件（六次播遷事件）。總結來說，我們的結果顯示整個多稜攀蜥於過去近五百萬年的歷史主張着此物種起源於南琉球及台灣地區後經歷了早期的割據事件接著經由跳島播遷（island-hopping dispersal）拓殖至此物種分布的最東北。

關鍵字

飛蜥科 ； 祖先區域重建 ； 歷史生物地理 ； 多稜攀蜥 ； 琉球群島 ； 台灣島

並列摘要

Continental archipelagoes are suitable objects for examination of alternative hypotheses in biogeography. Vicariance was once believed to be the predominant mechanism that influenced distribution of organisms. However, dispersal as the alternative one has been widely discussed in recent years. The Ryukyu archipelago and Taiwan are suitable continental archipelago to study these alternative hypotheses in East Asia. In this study, we aim to infer the historical biogeography of a dispersal-limited terrestrial vertebrate, the Okinawa tree lizard (Japalura polygonata). We obtained 246 individuals sampled from 10 localities of Ryukyu archipelago and 17 localities in Taiwan, covering the entire distribution range of this species. DNA sequences of the mitochondrial cytochrome b, 16S ribosomal RNA, nuclear Bach-1 and Rag-1 genes were obtained from these individuals. We employed maximum parsimony, maximum likelihood and Bayesian inference analyses to reconstruct phylogenetic relationships among haplotypes. We also performed BEAST molecular dating, dispersal-extinction-cladogenesis (DEC) model and statistical dispersal-vicariance analysis (S-DIVA) to reconstruct ancestral geographical ranges and the divergence time of the populations of J. polygonata. Phylogeny of J. polygonata haplotypes revealed the existence of eight major clades, which were not consistent with the four currently recognized subspecies. Biogeographic and divergence time reconstructions showed that J. polygonata originated from Taiwan and the southern Ryukyus 4.56 million years ago (early Pliocene). The DEC models analysis showed that there were one vicariance event and two dispersal events occurred in the middle Pliocene (3.67 MYA) and late Pliocene (3.07 MYA), respectively, and one vicariance event and two dispersal events occurred in the Pleistocene (1.32 and 0.47 MYA, respectively). The S-DIVA analysis revealed similar results but revealed more dispersal events than DEC model analysis (six dispersal events). These results support that both dispersal and vicariance mechanisms were major mechanisms shaping the current distribution of J. polygonata in East Asian archipelago and Taiwan. In conclusion, the biogeographic history of J. polygonata suggested that this species was originated from Taiwan and southern Ryukyu region, experienced historical vicariance events, and then colonized to their north most distribution by island-hopping dispersal during the past 4.56 million years.

並列關鍵字

Agamidae ； ancestral area reconstruction ； historical biogeography ； Japalura polygonata ； Ryukyu archipelago ； Taiwan

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