Table of Contents
  • Volume 50 Issue 2

    Cover illustration: Comparing phylogenetic signal across plastid introns, spacers, and genes. See BARNISKE et al., pp. 85–108 in this issue.
      
      Research Articles
    • Anna-Magdalena BARNISKE, Thomas BORSCH, Kai MÜLLER, Michael KRUG, Andreas WORBERG, Christoph NEINHUIS, Dietmar QUANDT
      2012, 50 (2): 85–108
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      Recent phylogenetic analyses revealed a grade with Ranunculales, Sabiales, Proteales, Trochodendrales, and Buxales as first branching eudicots, with the respective positions of Proteales and Sabiales still lacking statistical confidence. As previous analyses of conserved plastid genes remain inconclusive, we aimed to use and evaluate a representative set of plastid introns (group I: trnL; group II: petD, rpl16, trnK) and intergenic spacers (trnL-F, petB-petD, atpB-rbcL, rps3-rpl16) in comparison to the rapidly evolving matK and slowly evolving atpB and rbcL genes. Overall patterns of microstructural mutations converged across genomic regions, underscoring the existence of a general mutational pattern throughout the plastid genome. Phylogenetic signal differed strongly between functionally and structurally different genomic regions and was highest in matK, followed by spacers, then group II and group I introns. The more conserved atpB and rbcL coding regions showed distinctly lower phylogenetic information content. Parsimony, maximum likelihood, and Bayesian phylogenetic analyses based on the combined dataset of non-coding and rapidly evolving regions (>14 000 aligned characters) converged to a backbone topology of eudicots with Ranunculales branching first, a Proteales–Sabiales clade second, followed by Trochodendrales and Buxales. Gunnerales generally appeared as sister to all remaining core eudicots with maximum support. Our results show that a small number of intron and spacer sequences allow similar insights into phylogenetic relationships of eudicots compared to datasets of many combined genes. The non-coding proportion of the plastid genome thus can be considered an important information source for plastid phylogenomics.
    • Gandour MHEMMED, Hessini KAMEL, Abdelly CHEDLY
      2012, 50 (2): 109–118
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      It is a long-standing debate in evolutionary biology whether natural selection can generate divergence in the face of gene flow. Comparative studies of quantitative genetic and neutral marker differentiation have provided means for detecting the action of selection and random genetic drift in natural populations. We estimated the degree of population divergence in several quantitative traits and compared these estimates with that based on presumably neutral molecular markers (random amplified polymorphic DNA [RAPD]). This approach allowed us to disentangle the effects of divergent selection from that of other evolutionary forces. Nine populations of Cakile maritima, which encompasses the complete range of distribution of this species in Tunisia, were examined. We found a high proportion of total genetic variance to be among populations and among ecoregions for quantitative traits (range of QST: 0.44–0.88) and a moderate one for RAPD markers (GST: 0.081). In addition, almost all characters displayed a significant higher QST than GST, indicating occurrence of phenotypic plasticity and local adaptation. The latter is explicable as there is no reason to expect that natural selection would affect in similar fashion all traits and affect all populations at a similar level. We also found a negative and significant correlation between genetic variation in molecular marker loci and quantitative traits at the multitrait scale. This result attests that the evolution of these markers in C. maritima were not paralleled, suggesting that the degree of genetic differentiation in neutral marker loci is closely predictive of the degree of differentiation in loci coding quantitative traits and the majority of these neutral markers negatively controlled the studied quantitative traits.
    • Chang-Qiu LIU, Shuang-Quan HUANG
      2012, 50 (2): 119–124
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      Variation in floral allocation within inflorescences has been attributed to resource competition and/or architectural effect. The two hypotheses were extensively studied and both hypotheses were partly supported by previous studies. However, the relative importance of resource competition and architectural effect may vary with stages of floral ontogeny in a species. To detect the effects of ontogenetic stages on floral variation, we manipulated the 6-flowered inflorescences of Adenophora jasionifolia (Campanulaceae) by early, late, and non-thinning flowers. Our results indicated that pollen and ovule production of the remaining flowers were not significantly different between early and late thinning manipulations, suggesting that floral sex allocation was determined far before flowering, in support of the architectural effect hypothesis. Under hand-pollination treatments, early thinning but not late thinning resulted in a significant increase in seed number and seed set of the remaining flowers. Therefore, the increase in seed production of the remaining flowers related to the floral ontogeny. The resource competition for floral allocation was significant under early thinning rather than late thinning manipulation. Our results suggest that studies on floral variation within inflorescences should take into account the stages of floral ontogeny.
    • Hua-Fen ZHANG, Hai-Bo OUYANG, Jin-Yan DU,Shou-Zhou ZHANG,Yong LI, Hong WU
      2012, 50 (2): 125–134
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      Taxonomists are divided over the infrageneric classification and species delimitation within the genus Cycas. The division is largely determined by whether a broad or narrow species concept is adopted, the latter approach being based on apparently minor morphological differences. It is well known that cytokinesis in the cells of pollen provides important evidence for plant taxonomy, particularly at the higher taxonomic level. Here we present the first broad comparison of the cytokinesis of male meiosis in five species of Cycas. A comparative analysis of microsporogenesis in Cycas was carried out using conventional microscopy, semi-thin sectioning, histochemistry, and fluorescence microscopy with a focus on the cytokinesis of meiosis in the pollen of dividing cells. Our observations confirmed that, contrary to previous reports, the cytokinesis in male meiosis of five species in Cycas is simultaneous at the end of second meiosis. The basic model of microsporogenesis and its systematic implications in Cycas is discussed based both on previous reports and our new results.
    • Yi-Min ZHAO, Wei WANG, Shu-Ren ZHANG
      2012, 50 (2): 135–145
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      Aletris, containing approximately 21 species, is the largest genus in Nartheciaceae, and is disjunctively distributed in eastern Asia and eastern North America. Its delimitation has been controversial because it is uncertain whether Metanarthecium should be included in the genus. Although there are a few molecular phylogenetic studies on Aletris, the interspecific relationships within the genus have never been evaluated in a phylogenetic context. Here we used two cpDNA loci, matK and trnL-F, to delimitate Aletris and discuss the phylogeny within the genus. Phylogenetic analyses showed Metanarthecium might be distantly related to Aletris. This is also supported by morphological, palynological, cytological, and phytochemical data. Therefore, Metanarthecium should be excluded from Aletris. Within Aletris, there are two major clades: A. farinosa and A. lutea of eastern North America and A. glabra of eastern Asia form clade A; and the remaining Asian species form clade B. The Asian clade includes three subclades: subclade I (two varieties of A. pauciflora, and A. glandulifera and A. megalantha), subclade II (three samples of A. laxiflora), and subclade III (all other sampled Asian species). Based on phylogenetic relationships, A. pauciflora var. khasiana deserves a specific status, and A. gracilipes, formerly a synonym of A. laxiflora, should be reinstated. The reconstruction of the perianth evolution indicates that perianth connate halfway and glabrous on abaxial surface are plesiomorphic for Aletris and Nartheciaceae. Farinose-glutinous perianth is a diagnostic character for clade A.
    • Ying-Wen SHENG, Wen ZHANG, Dan ZHAO, Hong-Wei WANG
      2012, 50 (2): 146–152
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      A critical reassessment of the morphological features of two closely related red algal genera, Grateloupia C. Agardh and Sinotubimorpha W. X. Li & Z. F. Ding (Halymeniaceae), pointed out that members of the two genera had most morphological characteristics in common, including the Grateloupia type auxiliary cell ampullae. Sinotubimorpha hitherto was distinguished from Grateloupia by: (i) the hollow axis; (ii) the presence of secondary filaments in ampullae; (iii) 1- to 3-celled carpogonial branch; and (iv) the occasional production of 1- to 4-celled flanking filaments on carpogonium. However, when these features were re-examined among 37 Chinese species of genera described in Flora Algarum Marinarum Sinicarum and one newly reported species, Grateloupia orientalis, we found that it was difficult to draw a clear-cut distinction between the two genera based only on morphological differences. In rbcL sequence analysis, all the species of Sinotubimorpha with G. catenata formed a single monophyletic subclade within the large Grateloupia clade of the Halymeniaceae. It is therefore suggested that all the Chinese species of Sinotubimorpha, S. catenata, S. guangdongensis, S. qingdaoensis, S. claviformis, and S. ramosissima should be synonymous with G. catenata, and that Sinotubimorpha should be included in synonymy under Grateloupia.
    • Kanokorn RUEANGSAWANG, Pranom CHANTARANOTHAI, David A. SIMPSON
      2012, 50 (2): 153–162
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      Seed morphology provides some of the most important characters for species delimitation in Justicia (Acanthaceae). The seed morphology of 30 species from Thailand was studied using stereomicroscopy and scanning electron microscopy. Variation was seen in size, color, and shape. The range in seed size is 0.71–4.52 mm in length and 0.74–4.48 mm in width. The color varies from pale to dark brown, pale yellow, yellowish red, or dark green. The shape varies from ovoid to ellipsoidal, orbicular, suborbicular, or heart-shaped. Five different morphological types are proposed according to features of the testa. The seed morphology of each type is described, illustrated, and discussed according to its taxonomic significance. A key to identify the different types is also presented.
    • Ching-Long YEH, Shih-Wen CHUNG, Yu-Wen KUO, Tian-Chuan HSU, Chong-Sheng LEOU, Shin-Jie HONG, Chuan-Rong YEH
      2012, 50 (2): 163–169
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      Zingiber shuanglongensis sp. nov. is a species endemic to Taiwan, China, that has been found in Nantou and Kaohsiung. In this study, the new Zingiber species is illustrated and the results of morphological and phylogenetic comparisons with other related taxa are presented. Morphologically, Z. shuanglongensis can be readily distinguished from Z. kawagoii, the most closely related species, by its shorter spike, whitish corolla tube, the longer lateral lobes of its labellum, and its persistent bract. In addition, phylogenetic analyses based on nuclear ribosomal internal transcribed spacer and matK data indicated that Z. shuanglongensis is well separated from Z. kawagoii with high support. Combining the morphological characters and molecular analysis, we confirm that Z. shuanglongensis is a new species of Zingiber.
Editors-in-Chief
Song Ge
Jun Wen
Impact Factor
2.779
JCR 2019 IF ranking: 56/234 (Plant Sciences, top 23.72%, Q1 quartile)
Journal Abbreviation: J Syst Evol
ISSN: 1674-4918 (Print)
1759-6831 (Online)
CN: 11-5779/Q
Frequency: Bi-monthly

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