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资助项目
0.05). For some populations, germination capacity in 12-h photoperiod was significantly higher than that in completed darkness（W-FD: P < 0.01, W-JD: P < 0.05）.Genetic variation within and among six populations was assessed using AFLP markers. Genetic diversity was higher at species level (PPL = 69.19%, HE = 0.221) than at population level (PPL = 26.22%, HE = 0.095, Is =0.140), and populations in southeast Yunnan were strongly differentiated from those in southwest Yunnan (Nei’s GST = 0.575; FST = 0.655). UPGMA analysis demonstrated a clear genetic division between the two populations from DeHong (SW Yunnan; D-JD and D-HG) and the four from WenShan (SE Yunnan; W-FD, W-LH, W-ML, and W-MG). Within-population genetic variation was significantly correlated with population isolation (r(PPL) = -0.94, P = 0.006; r(HE) = -0.85, P = 0.032; r(Is) = -0.87, P = 0.025), but not with population size (r(PPL) = 0.63, P = 0.178; r(HE) = 0.54, P = 0.268; r(Is) = 0.56, P = 0.249).","jscount":"1","jsurl":"/simple-search?field1=all&field=dc.project.title_filter&advanced=false&query1=Hainan&&fq=dc.project.title_filter%3ACraigia%5C+yunnanensis%5C+W.%5C+W.%5C+Smith%5C+%5C%26%5C+W.%5C+E.%5C+Evans%5C+%5C%28Tiliaceae%5C%29%5C+is%5C+an%5C+endangered%5C+deciduous%5C+tree%5C+species%5C+which%5C+has%5C+high%5C+scientific%5C+and%5C+economic%5C+value.%5C+C.%5C+yunnanensis%5C+is%5C+seriously%5C+threatened%5C+and%5C+has%5C+been%5C+pushed%5C+to%5C+the%5C+verge%5C+of%5C+extinction%5C+due%5C+to%5C+vegetation%5C+destruction%5C+in%5C+China%5C+and%5C+consequent%5C+contraction%5C+of%5C+its%5C+distribution.%5C+Hence%2C%5C+it%5C+was%5C+listed%5C+as%5C+a%5C+nationally%5C+rare%5C+and%5C+endangered%5C+plant%5C+in%5C+1999%5C+and%5C+has%5C+also%5C+been%5C+proposed%5C+as%5C+a%5C+second%5C-ranked%5C+plant%5C+for%5C+national%5C+protection%5C+in%5C+China%5C+and%5C+included%5C+in%5C+IUCN%5C+red%5C+list.%5C+As%5C+a%5C+scientifically%5C+important%5C+and%5C+valued%5C+tree%5C+species%5C+with%5C+endangered%5C+status%2C%5C+the%5C+wild%5C+populations%5C+of%5C+C.%5C+yunnanensis%5C+therefore%5C+represent%5C+is%5C+a%5C+genetic%5C+resource%5C+that%5C+must%5C+be%5C+conserved.%5C+To%5C+provide%5C+basic%5C+information%5C+for%5C+its%5C+conservation%2C%5C+the%5C+population%5C+dynamics%5C+and%5C+population%5C+size%5C+structures%2C%5C+pollination%5C+biology%5C+and%5C+breeding%5C+system%2C%5C+eleven%5C+fitness%5C-related%5C+characters%5C+and%5C+the%5C+genetic%5C+variability%5C+based%5C+on%5C+AFLP%5C+were%5C+comprehensively%5C+studied.%5C+The%5C+main%5C+results%5C+are%5C+summarized%5C+as%5C+follows%5C%3A%5C+A%5C+total%5C+of%5C+six%5C+wild%5C+populations%5C+of%5C+C.%5C+yunnanensis%5C+were%5C+found%5C+in%5C+two%5C+disjunct%5C+regions%5C+of%5C+Yunnan%2C%5C+i.e.%5C+WenShan%5C+%5C%28SE%5C+Yunnan%5C%29%5C+and%5C+DeHong%5C+%5C%28SW%5C+Yunnan%5C%29%2C%5C+from%5C+2005%5C+to%5C+2007.%5C+Additionally%2C%5C+in%5C+all%5C+but%5C+one%5C+of%5C+the%5C+populations%5C+we%5C+detected%2C%5C+mature%5C+trees%5C+were%5C+felled%5C+between%5C+2005%5C+and%5C+2007%2C%5C+so%5C+destruction%5C+of%5C+most%5C+of%5C+these%5C+populations%5C+is%5C+ongoing.%5C+Across%5C+the%5C+six%5C+populations%5C+of%5C+extant%5C+C.%5C+yunnanensis%5C+found%5C+during%5C+our%5C+study%2C%5C+the%5C+total%5C+number%5C+of%5C+mature%5C+%5C%28reproductive%5C%29%5C+individuals%5C+detected%5C+was%5C+584%5C+in%5C+2007%EF%BC%8Cplus%5C+larger%5C+numbers%5C+of%5C+seedling%5C+and%5C+resprouts%5C+from%5C+cut%5C+trunks.%5C+The%5C+result%5C+of%5C+surveying%5C+Population%5C+structure%5C+showed%5C+that%5C+there%5C+are%5C+two%5C+regeneration%5C+types%5C+which%5C+are%5C+seedlings%5C+and%5C+sprouts.%5C+Seedlings%5C+occurred%5C+abundantly%5C+in%5C+gaps%5C+or%5C+open%5C+areas%5C+and%5C+the%5C+size%5C+class%5C+frequency%5C+distributions%5C+were%5C+often%5C+discontinuous%2C%5C+and%5C+the%5C+same%5C+general%5C+pattern%5C+occurred%5C+in%5C+all%5C+the%5C+investigated%5C+populations%5C+for%5C+juveniles%5C+and%5C+adults.%5C+The%5C+numbers%5C+of%5C+seed%5C-origin%5C+individuals%5C+did%5C+however%5C+decline%5C+sharply%5C+with%5C+increasing%5C+size%2C%5C+indicating%5C+a%5C+high%5C+mortality%5C+rate%5C+going%5C+from%5C+seedling%5C+to%5C+sapling%5C+stage%5C+may%5C+be%5C+a%5C+problem%5C+for%5C+this%5C+species.%5C+Additionally%2C%5C+the%5C+cash%5C+crop%5C+cultivation%5C+and%5C+logging%5C+seriously%5C+threaten%5C+the%5C+survival%5C+of%5C+the%5C+species.%5C+We%5C+conducted%5C+field%5C+observations%5C+and%5C+artificial%5C+pollination%5C+experiments%5C+on%5C+the%5C+floral%5C+biology%2C%5C+pollination%5C+process%5C+and%5C+breeding%5C+system%5C+of%5C+Craigia%5C+yunnanensis%5C+in%5C+Fadou%2C%5C+Xichou%5C+county%5C+of%5C+Yunnan%5C+province.%5C+The%5C+lifespan%5C+of%5C+a%5C+single%5C+hermaphrodite%5C+flower%5C+is%5C+approximately%5C+3%5C-4%5C+days.%5C+A%5C+cyme%5C+has%5C+2%5C-9%5C+flowered.%5C+The%5C+flowering%5C+period%5C+of%5C+an%5C+inflorescence%5C+is%5C+usually%5C+5%5C-14%5C+days.%5C+The%5C+flowers%5C+of%5C+C.%5C+yunnanensis%5C+were%5C+protandrous.%5C+The%5C+stamens%5C+were%5C+within%5C+petal%5C-like%5C+staminodes%5C+in%5C+the%5C+opening%5C+flowers%5C+until%5C+the%5C+flower%5C+withered.%5C+Without%5C+touchment%2C%5C+the%5C+bractlike%5C+staminodes%5C+can%E2%80%99t%5C+open.%5C+Self%5C-pollination%5C+was%5C+partially%5C+avoided%5C+by%5C+temporal%5C+and%5C+spatial%5C+isolation%5C+of%5C+male%5C+and%5C+female%5C+organs%5C+within%5C+the%5C+same%5C+flower.%5C+However%2C%5C+autogamous%5C+and%5C+geitonogamous%5C+pollination%5C+is%5C+unavoidable%5C+because%5C+of%5C+the%5C+large%5C+number%5C+of%5C+flowers%5C+on%5C+a%5C+single%5C+tree%5C+and%5C+the%5C+action%5C+of%5C+pollinators.%5C+The%5C+values%5C+of%5C+both%5C+OCI%5C+%5C%28%E2%89%A54%5C%29%5C+and%5C+P%5C%2FO%5C+%5C%281381%5C%29%5C+and%5C+the%5C+results%5C+of%5C+bagging%5C+tests%5C+indicated%5C+there%5C+was%5C+no%5C+apomixes%5C+in%5C+C.%5C+yunnanensis%5C+and%5C+the%5C+breeding%5C+system%5C+of%5C+the%5C+species%5C+was%5C+outcrossing%5C+with%5C+partial%5C+self%5C-compatibility%5C+and%5C+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species, usually called tree ferns, are considered as relicts of a time when dinosaurs were common. In recent several decades, the number of Cyatheaceae plants decreases dramatically. In order to find the reasons and provide directions for protecting these endangered plants, the biological characteristics of Cyatheaceae were surveyed. Using AFLP and cpDNA sequence variations, the genetic diversity and phylogeography of Sphaeropteris brunoniana were also analyzed. Based on these findings, implications for conservation strategies were discussed for this relict tree fern. Main results of the dissertation were summarized as follows, (1) Cyatheaceae plants have extensive distribution in Yunnan, China, and most of them distribute in southeast of Yunnan. In southeast, they usually inhabit margins of evergreen broad-leaved forests or secondary coniferous forests; however, the population update is very different and the age structure is unscientific. The spore of Cyatheaceae is trilete, radially symmetrical, and perinous. The spores of Alsophila species feature a ridged perine and a granular, verrucate or smooth exine. The spores of S. brunoniana are characterized by an incipient granular outermost layer and a verrucate exine. The metaphase chromosome numbers of gametophytes in the three examined species, viz. A. podophylla, A. gigantea and A. austro-yunnanensis, are 69, indicating that they are diploid and do not display variety in chromosome number. The chemical constituents of S. brunoniana are main simple and familiar compounds, such as saccharides, fatty acids and alcohols, and stigmasterols. (2) An unexpectedly high level of nDNA genetic diversity and low cpDNA diversity were detected in S. brunoniana. (3) This study showed that the genetic differentiation among populations within regions was low and between regions was significant. (4) There were several refugia of S. brunoniana in Yunnan during glacial periods. The Hainan populations were likely new colonizations and originated from Southeast Asia. (5) To retain existing genetic diversity, whether in situ or ex situ conservation or collection of germplasm is used, the populations of the two regions should be considered equally. Furthermore, ex situ conservation of this species should be preferably conducted on large populations.","jscount":"1","jsurl":"/simple-search?field1=all&field=dc.project.title_filter&advanced=false&query1=Hainan&&fq=dc.project.title_filter%3ACyatheaceae%5C+species%2C%5C+usually%5C+called%5C+tree%5C+ferns%2C%5C+are%5C+considered%5C+as%5C+relicts%5C+of%5C+a%5C+time%5C+when%5C+dinosaurs%5C+were%5C+common.%5C+In%5C+recent%5C+several%5C+decades%2C%5C+the%5C+number%5C+of%5C+Cyatheaceae%5C+plants%5C+decreases%5C+dramatically.%5C+In%5C+order%5C+to%5C+find%5C+the%5C+reasons%5C+and%5C+provide%5C+directions%5C+for%5C+protecting%5C+these%5C+endangered%5C+plants%2C%5C+the%5C+biological%5C+characteristics%5C+of%5C+Cyatheaceae%5C+were%5C+surveyed.%5C+Using%5C+AFLP%5C+and%5C+cpDNA%5C+sequence%5C+variations%2C%5C+the%5C+genetic%5C+diversity%5C+and%5C+phylogeography%5C+of%5C+Sphaeropteris%5C+brunoniana%5C+were%5C+also%5C+analyzed.%5C+Based%5C+on%5C+these%5C+findings%2C%5C+implications%5C+for%5C+conservation%5C+strategies%5C+were%5C+discussed%5C+for%5C+this%5C+relict%5C+tree%5C+fern.%5C+Main%5C+results%5C+of%5C+the%5C+dissertation%5C+were%5C+summarized%5C+as%5C+follows%2C%5C+%5C%281%5C%29%5C+Cyatheaceae%5C+plants%5C+have%5C+extensive%5C+distribution%5C+in%5C+Yunnan%2C%5C+China%2C%5C+and%5C+most%5C+of%5C+them%5C+distribute%5C+in%5C+southeast%5C+of%5C+Yunnan.%5C+In%5C+southeast%2C%5C+they%5C+usually%5C+inhabit%5C+margins%5C+of%5C+evergreen%5C+broad%5C-leaved%5C+forests%5C+or%5C+secondary%5C+coniferous%5C+forests%5C%3B%5C+however%2C%5C+the%5C+population%5C+update%5C+is%5C+very%5C+different%5C+and%5C+the%5C+age%5C+structure%5C+is%5C+unscientific.%5C+The%5C+spore%5C+of%5C+Cyatheaceae%5C+is%5C+trilete%2C%5C+radially%5C+symmetrical%2C%5C+and%5C+perinous.%5C+The%5C+spores%5C+of%5C+Alsophila%5C+species%5C+feature%5C+a%5C+ridged%5C+perine%5C+and%5C+a%5C+granular%2C%5C+verrucate%5C+or%5C+smooth%5C+exine.%5C+The%5C+spores%5C+of%5C+S.%5C+brunoniana%5C+are%5C+characterized%5C+by%5C+an%5C+incipient%5C+granular%5C+outermost%5C+layer%5C+and%5C+a%5C+verrucate%5C+exine.%5C+The%5C+metaphase%5C+chromosome%5C+numbers%5C+of%5C+gametophytes%5C+in%5C+the%5C+three%5C+examined%5C+species%2C%5C+viz.%5C+A.%5C+podophylla%2C%5C+A.%5C+gigantea%5C+and%5C+A.%5C+austro%5C-yunnanensis%2C%5C+are%5C+69%2C%5C+indicating%5C+that%5C+they%5C+are%5C+diploid%5C+and%5C+do%5C+not%5C+display%5C+variety%5C+in%5C+chromosome%5C+number.%5C+The%5C+chemical%5C+constituents%5C+of%5C+S.%5C+brunoniana%5C+are%5C+main%5C+simple%5C+and%5C+familiar%5C+compounds%2C%5C+such%5C+as%5C+saccharides%2C%5C+fatty%5C+acids%5C+and%5C+alcohols%2C%5C+and%5C+stigmasterols.%5C+%5C%282%5C%29%5C+An%5C+unexpectedly%5C+high%5C+level%5C+of%5C+nDNA%5C+genetic%5C+diversity%5C+and%5C+low%5C+cpDNA%5C+diversity%5C+were%5C+detected%5C+in%5C+S.%5C+brunoniana.%5C+%5C%283%5C%29%5C+This%5C+study%5C+showed%5C+that%5C+the%5C+genetic%5C+differentiation%5C+among%5C+populations%5C+within%5C+regions%5C+was%5C+low%5C+and%5C+between%5C+regions%5C+was%5C+significant.%5C+%5C%284%5C%29%5C+There%5C+were%5C+several%5C+refugia%5C+of%5C+S.%5C+brunoniana%5C+in%5C+Yunnan%5C+during%5C+glacial%5C+periods.%5C+The%5C+Hainan%5C+populations%5C+were%5C+likely%5C+new%5C+colonizations%5C+and%5C+originated%5C+from%5C+Southeast%5C+Asia.%5C+%5C%285%5C%29%5C+To%5C+retain%5C+existing%5C+genetic%5C+diversity%2C%5C+whether%5C+in%5C+situ%5C+or%5C+ex%5C+situ%5C+conservation%5C+or%5C+collection%5C+of%5C+germplasm%5C+is%5C+used%2C%5C+the%5C+populations%5C+of%5C+the%5C+two%5C+regions%5C+should%5C+be%5C+considered%5C+equally.%5C+Furthermore%2C%5C+ex%5C+situ%5C+conservation%5C+of%5C+this%5C+species%5C+should%5C+be%5C+preferably%5C+conducted%5C+on%5C+large%5C+populations."},{"jsname":"lastIndexed","jscount":"2024-04-15"}],"资助项目","dc.project.title_filter")'>
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