在系统发育分析中编码空位

空位包含了可用于系统发育分析的进化信息.为了准确地计算系统发育关系,空位包含的信息应该予以考虑.本文讨论了7种最常用的空位编码方法,并举例说明这些方法的编码原理.另外,本文还介绍了一些经验用以帮助研究者在使用现有的系统发育软件时选择空位编码方法.但是,所有的空位编码方法都有其优点和缺点,需要提出新的空位编码方法才能使空位信息在系统发育分析中得以充分地应用.     

PRELIMINARY ANALYSIS OF QUANTITATIVE GENETICS AND PHENOTYPIC PLASTICITY IN AULACOSEIRA SUBARCTICA (BACILLAR-IOPHYTA)

Several clones of Aulacoseira subarctica were isolated from Yellowstone, Lewis, and East Rosebud Lakes (Montana, Wyoming). Two to four clones from each lake were grown in batch cultures under three light intensities, 2, 11.4 and 115 μE m⁻² s⁻¹. Clones were conditioned to their light environment for a three-week period. Inoculants from the conditioned clones taken during log phase of growth, were grown until in log phase, then samples were collected. Five randomly chosen valves for 2 replicates of each clone were examined using a scanning electron microscope and captured on film at a magnification of 20,000x. Each image was digitized and quantitative morphometric characters were measured. A preliminary quantitative genetic analysis was performed on selected characters within each light environment. Plasticity of characters within clones across the three light regimes were also examined. The amount of variability found within characters in A. subarctica will be discussed in terms of environmental, genetic, and microenvironmental sources.     

FIVE NEW GOMPHONEMA SPECIES (BACILLARIOPHYCEAE) FROM RIVERS IN SOUTH AFRICA AND SWAZILAND1

Diatom material from South Africa and Swaziland was examined with light and scanning electron microscopy. Five new taxa are proposed: Gomphonema crocodilei, G. quasicrocodilei, G. venusta, G. latistigmata, and G. cholnokyi. Gomphonema venusta has been previously misidentified as Gomphonema clevei Fricke and G. cholnokyi as G. subclavatum (Grunow) Grunow. All of the species possess biseriate striae, areolae with external vela, a true stigma, and marginal laminae underlying the valve margin and mantle. Compared to the other members of gomphonemoid lineage, the five new species show greatest similarity to Gomphoneis mesta Passy-Tolar & Lowe, G. magna Kociolek & Stoermer, and G. rhombica (Fricke) Merino, García, Hernández-Mariné, & Fernández and to the Herculeana lineage of Gomphoneis sensu Kociolek and Stoermer. The most recent phylogenetic analysis of the genus Gomphoneis showed that the two lineages of the genus. Herculeana and Elegans, are not monophyletic. The Herculeana lineage is more closely allied to Gomphonema than to the Elegans lineage. Since the Elegans lineage contains the generitype of Gomphoneis (G. elegans (Grunow) Cheve), and the species described here are more closely related to the Herculeana lineage, we have assigned them to Gomphonema.     

中国尾蛱蝶属系统发育分析——基于雄性外生殖器形态特征

在对中国尾蛱蝶属雄性外生殖器解剖研究的基础上,选取了23个雄性外生殖器解剖特征,利用Paup4.0b10系统发育分析软件,分析探讨了中国尾蛱蝶属系统发育关系。结果表明:中国尾蛱蝶属9个种分为2个支系,一支系由凤尾蛱蝶Polyura arja、窄斑凤尾蛱蝶P.athamas及黑凤尾蛱蝶P.schreiber3种组成,另一支系由二尾蛱蝶P.narcaea、沾襟尾蛱蝶P.posidonius、忘忧尾蛱蝶P.nepenthes、异纹尾蛱蝶P.mutata、大二尾蛱蝶P.eudamippus及针尾蛱蝶P.dolon6种组成。两大支系均以渐次方式演化;凤尾蛱蝶与窄斑凤尾蛱蝶、大二尾蛱蝶与针尾蛱蝶各自互为姊妹群关系。     

贵州空棘鱼属的修订与系统发育分析

依据在云南富源中三叠世法郎组竹杆坡段发现的新材料,对关岭贵州空棘鱼(Guizhoucoelacanthus guanlingensis)进行了补充描述,并修订了鼻骨、顶骨、后顶骨、额外肩胛骨、眶后骨、偶鳍、鳞片等特征。系统发育分析表明,贵州空棘鱼属与Whiteia+Piveteauia构成姐妹群,其共有离征包括:两对顶骨的大小相近,第一背鳍鳍条数小于8。建议将贵州空棘鱼属归入怀特鱼科(Whiteiidae)。     

THE ORIGIN OF AN ORGAN: PHYLOGENETIC ANALYSIS OF EVOLUTIONARY INNOVATION IN THE DIGESTIVE TRACT OF FLIES (INSECTA: DIPTERA)

The cardia, a prominent digestive tract organ consisting of several specialized cell types, occurs throughout the “higher” or muscoid flies, division Schizophora of order Diptera. Phylogenetic analysis of cellular organization in 65 insect species from 36 families indicates that this organ originated within the order Diptera from ancestrally undifferentiated tissues. “Lower” flies, suborder “Nematocera,” display little or no epithelial cell specialization at the corresponding site. Scorpionflies of the outgroup order Mecoptera are similarly unspecialized. Intermediate levels of cellular specialization occur in Tabanomorpha, Asilomorpha and Aschiza, dipteran taxa that diverge between “Nematocera” and Schizophora. The distribution of epithelial characteristics suggests that the cardia evolved through a sequence of simple tissue transformations, combining changes in epithelial configuration with local differentiation of cell structure and function. The evolution of locally specialized cell types implies the emergence of structural genes and regulatory mechanisms through the modification of an ancestral genome that had not supported such extensive differentiation. Comparison of localized gene expression in Drosophila melanogaster with that in other fly species having greater or lesser degrees of cell specialization may provide a practical model system for studying specific patterns of mutation associated with such evolutionary innovation.     

多样性排序:方法与实例

多样性已经成为生态学理论与实践中的一个很重要的概念 ,很多多样性指数被引进或设计出来 ,并被广泛地应用于生态系统管理以及环境监测与评价之中。然而 ,很多学者对其也提出了疑议 ,因为当用不同的多样性指数对一组群落进行比较时会得出不同的顺序。Patil和Taillie等人提出用含有一个参数的多样性指数族可以潜在地解决这个问题。本文对这个类型的 1 4种方法做了评述 ,并将其分为 4组。证明了组内各方法间是等价的 ,而不同组的各方法间是不等价的。并认为在进行多样性排序时 ,Patil和Taillie的“右尾和”方法应属首选 ,因为只需计算有限个数值 ,并且该方法判断了群落内多样性的高低。其次 ,Hulbert_Smith_Grassle的方法也值得推荐 ,因为该方法有直观而明确的意义 ,它是一个随机样本中期望包含的物种数目。作为实例 ,还将这些方法应用于北京东灵山地区的 3个森林群落多样性的比较     

MOLECULAR SYSTEMATICS OF ECTOCARPUS AND KUCKUCKIA (ECTOCARPALES, PHAEOPHYCEAE) INFERRED FROM PHYLOGENETIC ANALYSIS OF NUCLEAR- AND PIASTTD-ENCODED DNA SEQUENCES

The phylogeny of Ectocarpus and Kuckuckia strains representing widely separated populations from both hemispheres was inferred from sequence analysis of the internal transcribed spacers of the nuclear ribosomal DNA (ITS 1—5.8S-ITS 2) and the spacer region in the plastid-encoded ribulose- bis -phosphate-carboxylase (RUBISCO) cistron (partial rbc L-spacer-partial rbc S ). Both sequences resulted in matching phylogenies, with the RUBISCO spacer region being most informative at the level of genera and species and the internal transcribed spacer sequences at the level of species and populations. Three major clades were formed by strains previously described by morphology and physiology as Kuckuckia, E. fasciculatus, and E. siliculosus, confirming the validity of these taxa . Ectocarpus and Kuckuckia are regarded as sibling taxa with respect to the outgroup species Feldmannia simplex, Hincksia mitchelliae, and Pilayella littoralis. The clade formed by sexual E. siliculosus strains and most asexual Ectocarpus strains was subdivided into several clades that are consistent with geographical races within E. siliculosus. The inferred phylogeny of Ectocarpus corresponds generally with results from cross-fertilization experiments, morphology, and lipid analysis. A hypothesis on the origin and dispersal of E. siliculosus suggests several natural dispersal events during periods of global cooling as well as recent and possibly anthropogenic dispersal events .     

RIMOPORTULAE IN EUPODISCUS RADIATUS (BACILLARIOPHYCEAE) FROM THE NORTHEASTERN GULF OF MEXICO1

Specimens of Eupodiscus radiatus Bailey from the northeastern Gulf of Mexico were examined with light and scanning electron microscopy. In contrast to previous studies of this taxon, we report the presence of two, rarely one, rimoportulae (labiate processes) between consecutive ocelli. This finding changes our understanding of the phylogenetic relationships in the family Eupodiscaceae.     

PHYLOGENETIC ANALYSIS OF BRACHIDINIUM CAPITATUM (DINOPHYCEAE) FROM THE GULF OF MEXICO INDICATES MEMBERSHIP IN THE KARENIACEAE1

Brachidinium capitatum F. J. R. Taylor, typically considered a rare oceanic dinoflagellate, and one which has not been cultured, was observed at elevated abundances (up to 65 cells · mL^?1) at a coastal station in the western Gulf of Mexico in the fall of 2007. Continuous data from the Imaging FlowCytobot (IFCB) provided cell images that documented the bloom during 3 weeks in early November. Guided by IFCB observations, field collection permitted phylogenetic analysis and evaluation of the relationship between Brachidinium and Karenia. Sequences from SSU, LSU, internal transcribed spacer (ITS), and cox1 regions for B. capitatum were compared with five other species of Karenia; all B. capitatum sequences were unique but supported its placement within the Kareniaceae. From a total of 71,487 images, data on the timing and frequency of dividing cells was also obtained for B. capitatum, allowing the rate of division for B. capitatum to be estimated. The maximum daily growth rate estimate was 0.22 d^?1. Images showed a range in morphological variability, with the position of the four major processes highly variable. The combination of morphological features similar to the genus Karenia and a phylogenetic analysis placing B. capitatum in the Karenia clade leads us to propose moving the genus Brachidinium into the Kareniaceae. However, the lack of agreement among individual gene phylogenies suggests that the inclusion of different genes and more members of the genus Karenia are necessary before a final determination regarding the validity of the genus Brachidinium can be made.     

SELENIUM: AN ESSENTIAL ELEMENT FOR GROWTH OF THE COASTAL MARINE DIATOM THALASSIOSIRA PSEUDONANA (BACILLARIOPHYCEAE)1,2

An obligate requirement for selenium is demonstrated in axenic culture of the coastal marine diatom Thalassiosira pseudonana (clone 3H) (Hust.) Hasle and Heimdal grown in artificial seawater medium. Selenium deficiency was characterized by a reduction in growth rate and eventually by a cessation of cell division. The addition of 10⁻¹⁰ M Na₂eO₃ to nutrient enriched artifical seawater resulted in excellent growth of T. pseudonana and only a slight inhibition of growth occurred at Na₂SeO₃ concentrations of 10⁻³ and 10_-2 M. By contrast, Na₂SeO₄ failed to support growth of T. pseudonana when supplied at concentrations less than 10⁻⁷ M and the growth rate at this concentration was only one quarter of the maximum growth rate. The addition of 10⁻³ and 10⁻² M Na₂SeO₄ to the culture medium was toxic and cell growth was completely inhibited. Eleven trace elements were tested for their ability to replace the selenium requirement by this alga and all were without effect. In selenium-deficient and selenium-starved cultures of T. pseudonana cell volume increased as much as 10-fold as a result of an increase in cell length (along the pervalvar axis) but cell width was constant. It is concluded that selenium is an indispensable element for the growth of T. pseudonana and it should be included as a nutrient enrichment to artificial seawater medium when culturing this alga.     

FLOW CYTOMETRIC ANALYSIS OF SPERMATOGENESIS IN THE DIATOM THALASSIOSIRA WEISSFLOGII (BACILLARIOPHYCEAE)1

Flow cytometry was used to detect and quantify sexual differentiation in the centric diatom Thalassiosira weissflogii (Grun.). Size (light scatter), chlorophyll, protein and DNA contents were measured for each cell throughout the process of differentiation. Male gametes were small round cells characterized by one complement of DNA and a lower protein and chlorophyll content than vegetative cells. Male gamete formation was induced by a long period of darkness (2 days) followed by a transfer to continuous light. Up to 30% of the initial cell population produced male gametes which appeared in the culture 14 h after release from darkness. Male gamete production was also detected in exponentially growing cultures in continuous light, but to a much smaller degree.     

SELENIUM: AN ESSENTIAL ELEMENT FOR GROWTH OF THE COASTAL MARINE DIATOM THALASSIOSIRA PSEUDONANA (BACILLARIOPHYCEAE)1,2

An obligate requirement for selenium is demonstrated in axenic culture of the coastal marine diatom Thalassiosira pseudonana (clone 3H) (Hust.) Hasle and Heimdal grown in artificial seawater medium. Selenium deficiency was characterized by a reduction in growth rate and eventually by a cessation of cell division. The addition of 10⁻¹⁰ M Na₂SeO₃ to nutrient enriched artificial seawater resulted in excellent growth of T. pseudonana and only a slight inhibition of growth occurred at Na₂SeO₃ concentrations of 10⁻³ and 10⁻² M. By contrast, Na₂SeO₄ failed to support growth of T. pseudonana when supplied at concentrations less than 10⁻⁷ M and the growth rate at this concentration was only one quarter of the maximum growth rate. The addition of 10⁻³ and 10⁻² M Na₂SeO₄ to the culture medium was toxic and cell growth was completely inhibited. Eleven trace elements were tested for their ability to replace the selenium requirement by this alga find all were without effect. In selenium-deficient and selenium-starved cultures of T. pseudonana cell volume increased as much as 10-fold as a result of an increase in cell length (along the pervalvar axis) but cell width was constant. It is concluded that selenium is an indispensable element for the growth of T. pseudonana and it should be included as a nutrient enrichment to artificial seawater medium when culturing this alga.     

FLOW CYTOMETRIC ANALYSIS OF SPERMATOGENESIS IN THE DIATOM THALASSIOSIRA WEISSFLOGII (BACILLARIOPHYCEAE)1

Flow cytometry was used to detect and quantify sexual differentiation in the centric diatom Thalassiosira weissflogii (Grun.). Size (light scatter), chlorophyll, protein and DNA contents were measured for each cell throughout the process of differentiation. Male gametes were small round cells characterized by one complement of DNA and a lower protein and chlorophyll content than vegetative cells. Male gamete formation was induced by a long period of darkness (2 days) followed by a transfer to continuous light. Up to 30% of the initial cell population produced male gametes which appeared in the culture 14 h after release from darkness. Male gamete production was also detected in exponentially growing cultures in continuous light, but to a much smaller degree.     

国产酸浆属（茄科）的叶表皮和种皮特征及其分类学意义

在光学显微镜和扫描电镜下观察了茄科酸浆属５种２变种及邻近属２种植物：辣椒和龙珠的叶表皮及种皮特征,发现上述植物的叶上、下表皮细胞表面观形状为不规则形,垂周壁浅波状、波状或深波状;一些类群的气孔器在上、下表皮均存在,另一些类群的气孔器则仅在下表皮存在,其类型一致为无规则型。扫描电镜下叶下表皮的特征,包括角质膜以及气孔外拱盖和拱盖内缘的特征,有一定的分类学价值。此外,种皮纹饰可作为区分酸浆属、辣椒和龙     

A PHYLOGENETIC ANALYSIS OF DIOON (ZAMIACEAE)

A phylogenetic analysis of all the intrageneric taxa of the genus Dioon Lindley (Zamiaceae) was undertaken by using chloroplast DNA restriction fragment length polymorphism analysis. Wagner parsimony analysis on a 187 character matrix yielded two equally parsimonious trees, differing only for the position of D. caputoi. The consensus tree has two well-defined major clades. The first is composed of D. mejiae, D. rzedowskii, and D. spinulosum; the second is composed of D. califanoi, D. caputoi, D. edule var. angustifolium, D. edule var. edule, D. holmgrenii, D. merolae, D. purpusii, D. tomasellii var. sonorense, and D. tomasellii var. tomasellii. A phenetic analysis of the same data showed results broadly congruent with the cladistic analysis. This resulting phylogeny is partially congruent with morphological data and is also compatible with the biogeography of the genus. Modem species of Dioon may have evolved as a consequence of a very fast succession of vicariance events that mainly occurred during the early Cenozoic. The short time between each of these events may not have allowed the accumulation of a large number of morphological synapomorphies for the groups of species.