Phylogeography of Pinus luchuensis species complex based on genetic variation of cp- and mtDNAs.

in International Symposium (poster summary), 國際研討會(摘要海報發表)
標題Phylogeography of Pinus luchuensis species complex based on genetic variation of cp- and mtDNAs.
AuthorsYu-Chung Chiang, 江友中
出版日期Jul 29 2004 12:0
會議地點Sakura, Chiba Pref.

Phylogeography of Pinus luchuensis species complex based on genetic variation of cp- and mtDNAs Tzen-yuh CHIANG1, Xue-jun GE2, Kuo-hsiang HUNG1, Tsai-wen HSU1, Yu-chung CHIANG3 and Shann-jye MOORE*4 (1Department of Life Science, Cheng-Kung University, Tainan, Taiwan 701; 2South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, PRC ; 3Department of Biology, Washington University, St. Louis, MO; 4Department of Life Science, Taiwan Normal University, Taipei, Taiwan ) Plants distributed across mainland and adjacent islands provide ideal materials for examining species and genetic divergence. Within a chain of islands of an archipelago, a stepping-stone migratory model is expected. Compared to mainland relatives, island species/ populations would display lower levels of genetic variability and significant, genetic differentiation given small population number and size due to limited, available habitats and geographical isolation. In this study, paternally transmitted chloroplast DNA and maternally inherited mitochondrial DNA were used to estimate the population structure and phylogeographical patterns of Pinus luchuensis, a species distributed across Ryukyu Archipelago (ssp. luchuensis), Taiwan (ssp. taiwanensis), and eastern China (ssp. hwangshanensis). In total, two major clades X and Y of cpDNA, consisting of subclades A-D and E-G, respectively, and two major clades α and β of mtDNA, consisting of subclades I-IV and V-VII, respectively, were identified. High levels of genetic diversities of both organelle DNAs were detected in these three ecologically dominant subspecies, except for that of cpDNA in ssp. hwangshanensis. Unexpectedly, the two island subspecies possess greater genetic polymorphisms than the mainland taxon. Given low possibilities of dispersal of winged seeds of these hard pines across straits, great Nm values deduced from mtDNA are likely to be attributable to ancestral polymorphisms that are shared between subspecies, a result consistent with recent divisions between mainland and islands populations based on geological evidence. In contrast to a general assumption of long-distance pollen dispersal in pines, lacking of the major clade X and subclade E of cpDNA in ssp. hwangshanensis indicates low possibilities of across-strait dispersal. A pattern of spatial partitioning of the organelle DNAs showing higher genetic diversity in islands than in the mainland, and in south than in north indicates that the P. luchuensis taxa experienced postglacial expansion. Subspecies. hwangshanensis may have been colonized via founders from islands, followed by expansion to its modern range.

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