碩士 / 國立彰化師範大學 / 生物學系 / 94 / The specimens were extensively collected from freshwater and brackish water from Taiwan and its offshore islands from July, 2003 to April, 2006. In this study, two tribus, three genera and fifteen species of extant Characeae, including one newly recorded genus, one undescribed species, and seven newly recorded species were identified by molecular analysis and morphological observations. Furthermore, the external characteristic, reproductive structures, geographical distribution and seasonal occurrence were described in detail.
In order to find the fittest model of nucleotide substitution, the rbcL gene sequence derived from forty-nine operation taxonomic units were tested by Modeltest software v3.7. Based on the Modeltest analysis, a GTR model with invariant sites and a gamma shape parameter was selected. The topology of the maximum parsimonious tree showed the Characeae formed a monophyletic clade with full statistical support (MP BS = 100, ML BS = 100, DI＞4, PP = 1.00). Among these assemblages, the Tribe Chareae was a monophyletic clade with full statistical support (Tribe Chareae clade, MP BS = 100, ML BS = 100, DI＞4, PP = 1.00), but the Tribe Nitelleae was a paraphyletic clade. Within the Tribe Chareae clade, Chara was a monophyletic clade with lower statistical support (MP BS = 59, ML BS = 58, DI=2, PP＜0.95), which indicated a sister group relationships to Lamprothmnium and formed a Chara-Lamprothamnium clade (MP = 100, ML=100, DI＞4, PP = 1.00). It was also strongly indicated a sister group relationship between Lychnothmnus and Nitellopsis which formed a Lychnothamnus-Nitellopsis clade (MP BS = 99, ML BS =100, DI＞4, PP = 1.00). Within the Tribe Nitelleae clade, Nitella was a monophyletic clade with lower statistical support (MP BS= 64, ML BS =63, DI=2, PP = 0.99), which is paraphyletic with respect to Tolypella.
In the Chara clade, the antheridium occurred below oogonium was the distinguished character to the other genera of Characeae. According to the rbcL gene, atpB gene and SSU rDNA sequences comparisons and the difference of oospore morphology, we suggested that C. australis R. Brown had a very close relationship with C. corallina Klein ex Willdenow and both species had the common ancestor of Chara braunii Gmelin. Due to the similarity of sequences and oospore morphology, we also suggested the speciation event between the former two species had occurred recently.
In the Lychnothamnus clade, an oogonium flanked by two lateral antheridia was the distinguished character to the other genera of Characeae. The endangered monospecific genus, Lychnothamnus (Ruprecht) Leohardi, was the first recorded genus to the freshwater algal flora of Taiwan, comprised a newly recorded species, Lychnothamnus barbatus (Meyen) Leonhardi. Besides, the mean oospore isopolarity index (ISI= 135-166) of the population in Taiwan was close to the population in Australia (ISI = 140-171), but quite differed from the population in Europe (ISI= 115-140). We suggested that the habitat in Taiwan was similar to Australian, or the populations occurred in Taiwan and Australia were homologous descents.
In the Nitella clade, two tiers of coronula cells and furcated branchlets were the distinguished characters to the other genera of Characeae. In this clade, one undescribed species, Nitella sp. and six newly recorded species, Nitella moriokae R.D. Wood, N. gracilens Morioka, N. inversa Imahori, N. japonica (A. Braun) Allen, N. vieillardii (A. Braun) Sakayama and N. mucronata (A. Braun) Miquel were identified. In this study, we found that the oospore wall ornamentations observed under SEM were phylogenetically conservative characters within the genus Nitella, these characters could be used to construct a taxonomic system at the sectional level.
| Identifer | oai:union.ndltd.org:TW/094NCUE5112008 |
| Date | January 2006 |
| Creators | Jui-Yu Chou, 周睿鈺 |
| Contributors | Wei-Lung Wang, 王瑋龍 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 115 |
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