A Phylogeographical Study Of Pinus Hwangshanensis

Studies on the evolutionary history of tertiary relic plants can help us tounderstand how climatic change affects genetic structure, population distributionand biodiversity, and can also provide us the theoretic guide for biodiversityconservation. In this study, a phylogeographic approach has been conducted inPinus hwangshanensis, which is distributed in southeastern China and has a longevolution history, and its relatives （Pinus luchuensis distributed in RyukyuArchipelago and Pinus taiwanensis in Taiwan Island）using mtDNA（nad1andnad4）and cpDNA（trnS-trnG and rpl16）fragments with wide sampling collection.Based on the distribution and relationship within haplotypes and the populationgenetic analysis, Our main objectives were to detect genetic structure, evolutionhistory and to determine the possible glacial refugia and the historical rangeexpansion events within P. hwangshanensis and its relatives. And we also discussedthe phylogenic relationship between P. hwangsanensis and its relatives P.luchuensis and P. taiwanensis.In our study, we totally obtained7mitotypes and17chlorotypes. The resultsshowed that genetic diversity and differentiation within P. hwangshanensispopulations were high(H_T=0.486, F_ST=0.872)based on mtDNA. There was muchmore gene flow, mainly pollen flow（Nm=11.58）and little seed flow（Nm=0.06）,among P. hwangshanensis and its relatives populations. Phylogeographic studyrevealed that P. hwangshanensis and its relatives had high genetic differentiation(G_ST=0.823，N_ST=0.873)based on mtDNA and U test showed that N_STvalue wassignificantly larger than G_STvalue（U=0.71，P＜0.01）.AMOVA indicated that38.84%of the total variation presented among threepines,53.29%among populations, and7.87%within populations in mtDNA. Whilein cpDNA,94.52%variation was within populations.We both detected the historical range expansion events in P. hwangshanensispopulations in mtDNA and cpDNA with the help of mismatch analysis and the expansion ages were calculated ranging from51to10thousand years and99to14thousand years ago respectively. The ages were earlier than the Last GlacialMaximum（LGM,18,000year ago）and inferred that Quaternary glaciation did notimpart much influence on speciation and divergence of plants in southeast China.The mitotypes distribution in P. hwangshanensis and its relatives was notsignificantly associated with geographic distances. This indicated that there mightbe multiple refugia in P. hwangshanensis and its relatives during Quaternaryglaciation.In this study, it was suggested that the evidence from mtDNA, cpDNA coupledwith nrDNA ITS data were not enough to support P. hwangshanensis as a separatespecies. We tended to agree with the opinion of Li et al.（1997） that P.hwangshanensis，P. luchuensis and P. taiwanensis were considered as Pinusluchuensis complex.