目前臺灣陸生動物之族群遺傳結構研究多針對脊椎動物，且大多數研究皆顯示陸生物種有東西部分群之現象。這些研究結果顯示臺灣陸生脊椎動物間類似的族群分化模式，可能由下列因素所造成：（一）中央山脈隆起產生之隔離效應：將臺灣的物種區隔成中央山脈東西部兩大族群，族群間不易進行基因交流；（二）更新世冰河期的影響：海平面降低之後，臺灣與大陸相連使生物可以進行大規模遷移。但是，臺灣陸生節肢動物之族群分化模式為何，是否與脊椎動物相似，尚無人加以討論。本研究利用廣泛分佈於東亞地區之人面蜘蛛（Nephila maculata（Fabricius 1793）），以粒線體核酸之細胞色素氧化脢I部分序列，探討臺灣及鄰近地區人面蜘蛛族群之遺傳結構及其與地理分佈之關係。樣本收集自琉球、臺灣北、中、南、東、主要離島及中國大陸東南，共24個族群189個個體，以步足肌肉之粒線體DNA增幅出617 bp之COI序列進行分析，並以同屬之Nephila clavata Koch 1877及Nephila antipodiana (Walckenaer 1841)作為外群。根據目前已獲得之序列，利用Mega 和PAUP軟體以距離法（neighbor-joining, NJ method）及檢約法（maximum parsimony, MP method）所建構之系統發育樹（NJ tree之bootstrap values為99 %，而MP tree 為100 %）顯示，臺灣及離島地區人面蜘蛛之基因型（haplotype）可分成兩個主群（lineage）。第一群：包含23個族群的大部分個體；第二群：包含中國大陸廣東、廣西、雲南及臺灣西部火炎山、騎龍、東北部雙連埤族群的部分個體；第三群：則僅有臺灣東北部雙連埤族群之三隻個體。由於臺灣全島的人面蜘蛛都有EA基因型之分佈，顯示臺灣地區人面蜘蛛並無東西族群顯著分化的現象，不像其他陸生脊椎動物般受中央山脈的地理阻隔。中國大陸東南部與臺灣地區皆有EA基因型的個體，因此臺灣人面蜘蛛的祖先族群可能來自於大陸。另外，系統發育樹上分群的結果及各基因型之分佈模式顯示，現生臺灣地區人面蜘蛛族群可能多次由中國大陸遷入。 Abstract Currently, most phylogeographic studies of terrestrial animals in Taiwan focus on vertebrates. Results from most studies showed that terrestrial vertebrates could be divided into eastern and western groups according to their population genetic structures. The common phylogeographic pattern exhibited by so many taxa was suggested to result from the upheaval of the Central Mountain Ridge, which led to isolation and differentiation of eastern and western populations. In this study, the widely-distributed giant wood spider Nephila maculata (Fabricius 1793) is used to investigate if population differentiation pattern of Taiwanese terrestrial arthropods resembles that of terrestrial vertebrates. Mitochondrial cytochrome oxidase I (COI) is used as genetic marker and its partial sequence is determined in 189 specimens collected from 24 localities in Ryukyu Islands, Taiwan and China. The 617 bases of COI gene are successfully amplified from DNA extracted from leg muscle and 11 haplotypes are identified from all specimens examined. Phylogenetic trees constructed by neighbor-joining (NJ) and maximum parsimony (MP) methods using Nephila clavata Koch 1877 and Nephila antipodiana (Walckenaer 1841) as the outgroups indicate that N. maculata populations can be separated into two major lineages, group A and group B, with high bootstrap values (99 % in NJ tree and 100 % in MP tree). Group A consists of most specimens from twenty-three localities. Group B consists of specimens from southeastern China and northwestern Taiwan. Another minor lineage is group C, which consists of 3 specimens from northeastern Taiwan. The wide distribution of the EA haplotype in western and eastern Taiwan indicats that the population differentiation pattern of N. maculata is different from those of terrestrial vertebrates examined so far. Central Mountain Ridge does not seem to be a major geographic barrier to N. maculata. The cooccurrence of specimens with EA haplotype in Taiwan and China suggests that some of the present populations in Taiwan might have splited from an ancestral population in mainland. In addition, judging from phylogenetic trees and the distribution patterns of haplotypes, entry of N. maculata from China to Taiwan might have occurred several times.
