| Summary: | 碩士 === 國立屏東科技大學 === 森林系所 === 103 === Amentotaxus, representing an ancient lineage of relic species, is a gymnosperm genus. Amentotaxus argotaenia species complex, including A. argotaenia Pilg., A. formosana H. L. Li, A. yunnanensis H. L. Li and A. poilanei (Ferr#westeur042# &; Rouane) D. K. Ferguson, was distributed in the Southeast Asia. In this study, we used multilocus (8 organelle loci, and 32 nuclear loci) to assess phylogenies and speciation models of this species complex. Amentotaxus formosana (π=0.0245；θ=0.0248) and A. yunnanensis (π=0.0215；θ=0.0230) exhibited the highest nucleotide diversity, and higher levels reflected features of a refugium. Only 3 genes tree showed the consistent topology with species tree, and most gene trees displayed various tree topologies. The incongruence of gene tree and species tree resulted from ancestral polymorphism or gene flow. IMa2 was used to estimate effective population size and gene flow of this species complex. The results indicated effective population sizes of ancient and extant populations have similar pattern, ancient gene flow is higher than recent gene flow. We suggested that allopatric speciation is the predominant mode for A. formosana. However, high levels of ancient and recent gene flow were detected among A. argotaenia, A. yunnanensis and A. poilanei and effective population size for extant population was lower than ancient population for these species. Both results suggested that parapatric speciation is likely for these species.
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