Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/21708
標題: 台灣產菟絲子屬植物之族群生態學研究
Population Ecology on the genus Cuscuta in Taiwan
作者: 廖國媖
Liao, Gwo-Ing
關鍵字: 菟絲子屬
族群生態學
形態
蟲癭
RAPD
花粉
台灣
出版社: 生命科學系
摘要: 本論文乃對台灣產菟絲子屬植物進行族群生態學的研究。檢視台灣5所標本館典藏較完整的72份菟絲子屬標本與採集自台灣本島及離島(含金馬地區)200多處的菟絲子屬植物,發現有多達76%的館藏標本被錯誤鑑定,本研究確認台灣的菟絲子屬有5個分類群:菟絲子(又名南方菟絲子;Cuscuta australis R. Br.)、平原菟絲子(C. campestris Yunck.)、中國菟絲子(C. chinensis Lam.)、台灣菟絲子(C. japonica Choisy var. formosana (Hayata) Yunck.)及日本菟絲子(C. japonica Choisy var. japonica),其中菟絲子在台灣可能已滅絕;而平原菟絲子自1964年起陸續採到標本,直到2000年才由本研究首次記錄。 依據花粉特徵將台灣產菟絲子屬區分為兩個花粉型:第一型為小粒、溝具顆粒、外層為細網狀雕紋,此型包括溝散布在表面的亞型—平原菟絲子,以及溝局限分布在赤道面的亞型—菟絲子與中國菟絲子;第二型為中間粒、溝具表面有小顆粒突起的顆粒、外層為網狀雕紋,此型有台灣菟絲子與日本菟絲子。 本研究應用RAPD方法探討菟絲子屬的遺傳變異,結果顯示RAPD方法確可應用在一單株可同時寄生於多種寄主的菟絲子屬植物。菟絲子屬種間具高度的DNA多型性,種內族群間亦存有DNA多型性。日本菟絲子與台灣菟絲子類緣關係最為親近;平原菟絲子與中國菟絲子類緣關係較親近,兩者與日本菟絲子及台灣菟絲子的類緣關係較疏遠。RAPD歸群的結果無法明確區分日本菟絲子與台灣菟絲子此兩變種,也看不出有種化的趨勢,兩者之外部形態差異不大且識別特徵都有中間型出現,另由花粉形態特徵亦無法明確區分兩者,推測日本菟絲子與台灣菟絲子間尚未產生遺傳分化,尚待進一步比對鄰近地區物種,有可能將兩者合併為同種,即日本菟絲子(C. japonica)。 本研究依據菟絲子屬植物的生長特性將物候期分為莖延長期、花芽期、開花期、盛花期、結果期、果熟期及種子萌芽期等7個時期。平原菟絲子植株生活周期較短,開花結果後整株枯萎,全年有2次果熟期;台灣菟絲子植株生活周期較長,10月始有花苞形成,10月到翌年2月陸續結花苞及開花,12月到翌年5月陸續結果且全株逐漸枯萎,種子約5∼9月萌芽。菟絲子屬進行種子繁殖的關鍵點,首先為種子萌芽,濕度是影響種子萌芽的主要氣象因子;其次為在有限時間內小苗先端要尋找到寄主且進行纏繞進而形成第一個吸器;最後為莖先端不斷尋找寄主、形成吸器及形成分枝以擴展範圍。菟絲子屬雖可以種子繁殖小苗進行有性生殖,但長成存活植株比例不高;另尚可藉由斷莖寄生、寄生部位的突起延伸、花序上抽枝以及疑似休眠芽的方式進行無性繁殖,以擴展其族群與分布範圍。 菟絲子屬的寄主相當多樣,包括蕨類、裸子植物、雙子葉植物及單子葉植物。平原菟絲子分布最廣,寄主多達265種(含種以下分類群);分布範圍次之的台灣菟絲子,寄主有182種(含種以下分類群)。針對台灣菟絲子寄生14種寄主植物進行喜好性觀測,台灣菟絲子對寄主是有喜好性的,其中對光果龍葵及通條樹特別喜好,但此喜好性與寄主所屬的分類群(門、科)、寄主為草本或木本或蔓性藤本、是否有毛或毛的疏密、是否有刺或刺的疏密等特性無關。 菟絲子屬的寄生現象極為複雜而多樣。本研究為台灣首次記錄到寄生植物被造瘿昆蟲寄生者,位於東引地區的平原菟絲子普遍形成瘤狀蟲癭,此現象或與造癭者的地理分布有關,推測此造癭者Smicronyx sp.(Coleoptera: Curculionidae)有寄主專一性,是菟絲子蟲癭象鼻蟲(dodder gall weevil)。此外,本研究為全球首次發現到寄生植物寄生在寄主癭部的現象,平原菟絲子寄生在海埔姜的癭部上,其吸器的絲狀細胞可入侵到癭室內,癭室內有許多隻蛛形綱節蜱屬(Aceria)的蟲體及卵,有的貼在侵入的絲狀細胞上,形成寄生植物、寄主植物與造癭者三者間複雜的生命共同體。
This study is focused on the population ecology of genus Cusuta of Convolvuaceae in Taiwan. Five taxa of Cuscuta in Taiwan are Cuscuta australis, C. campestris, C. chinensis, C. japonica var. formosana, and C. japonica var. japonica. Seventy-two specimens of Cusuta in 5 herbaria of Taiwan were carefully checked and approximately 76% were revised. This study firstly recorded C. campestris which has been collected since 1964 but all were incorrectly identified as C. chinensis or C. australis. C. australis has not been collected since 1972 and is probably now extinct. Two distinct types and two subtypes of Cuscuta pollen were recognized. Type 1 is small, and has colpus with granla, and sexine microreticulate, including C. australis, C. campestris and C. chinensis. Subtype 1a is pantocolpate, and occurs only in C. campestris. Subtype 1b is zonocolpate, and occurs in C. australis and C. chinensis. Type 2 is medium in size, and has colpus with granla, and scabrate processes on surface of granlum, sexine reticulate, including C. japonica var. formosana and C. japonica var. japonica. We studied the applicability of using RAPD analysis on the Cuscuta that one individual could simultaneously parasitize on several different hosts. There are both inter- and intra-specific DNA polymorphism in Cuscuta. The clustering of RAPD results can't distinguish C. japonica var. formosana from C. japonica var. japonica. The characters of external morphology and pollen are also not obvious enough to distinguish those two taxa. Phenological stages of Cuscuta could be divided into stem elongation stage, floral budding stage, flowering stage, flourishing floral stage, fruit stage, fruit-ripening stage and seed germinating stage. C. campestris shows shorter life cycle. There were two fruit-ripening stages in a year. It withered after fruiting. Cuscuta japonica var. formosana showed longer life cycle. It initiated flower buds in October and continuously flowering until next February. It continuously fruited and withered from December to next May. Both sexual and asexual reproductions existed in Cuscuta. Asexual reproductive methods included broken stem, protuberance elongation on parasitic part of stem, elongation from inflorescence stem, or by dormant-like bud. The range of host plants of Cuscuta included ferns, gymnosperms, dicotyledons, and monocotyledons. Based on 6-year observation in Taiwan, C. campestris was widely distributed and infested 265 species of vascular plants; C. japonica var. formosana distributed in central and southern parts and could parasitic attack 182 host species. Observation on host preference of C. japonica var. formosana to 14 host species showed that the parasite was most likely to parasitic attack Solanum americanum and Stachyurus himalaicus, but it was possible to dissociate choice from the taxa of families, the growth forms, and the hairs and spines on the stems. Parasitism phenomena in dodders included self-parasitism, hyperparasitism, gall formation by insects, and parasitism on host's galls. This study firstly recorded in Taiwan that parasitic plant was infected by gall-forming insects, and such as Cuscuta campestris formed globose or irregular and multilocular or monolocular galls by dodder gall weevil Smicronyx sp. (Coleoptera: Curculionidae). Furthermore, this study also firstly founded in the world that Cuscuta campestris parasitized on the galls of Vitex rotundifolia formed by Aceria sp. (Arachnida: Acariformes: Eriophyidae).
URI: http://hdl.handle.net/11455/21708
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