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Abstract A population of Meridion circulare var. circulare (Greville) C.A. Agardh from Inner Mongolia was found to produce Innenschalen or internal spores. Examination of this population with light and scanning electron microscopy showed morphological differentiation between vegetative and spore morphologies. Vegetative valves typically bear costae and one rimoportula at the headpole. Spores lack costae and have two rimoportulae, one at the headpole and the other at the footpole. There is plasticity in the production of valve morphologies, and a variety of vegetative valve and spore combinations are evident. This population of M. circulare var. circulare has initial valves of over 90 μm in length, and all of the initial cells encountered are acostate and bear two rimoportulae. These observations suggest that either spores are the product of sexual reproduction, or that initial valves may be produced parthenogenetically in Meridion. Spores as products of the sexual process have not been reported in diatoms previously, and parthenogenesis in Meridion was reported previously but discounted in other published reports. The plasticity of valve morphologies expressed in M. circulare var. ciculare, between vegetative valves and spores (and back) across a short temporal period suggests that diatoms can alter their cell wall structure dramatically and quickly in response to external variables. 相似文献
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W. GRANT INGLIS 《Biological journal of the Linnean Society. Linnean Society of London》1991,44(2):121-139
Taxonomic and systematic theory is hopelessly confused because the term character has nine different, previously confused, meanings. After a historical analysis, it is shown that some form pairs, one used in taxonomy (= operational identification of phenetic patterns of character x individual spread) and the other in systematics (= theoretical analysis of patterns of taxonomy). On the basis of a stratigramy model, names are given to each usage and are defined for taxonomy, then systematics, as necessary: component : (tax.) a defined bit-or-piece of one individual (no syst. meaning); homology : (tax.) conceptual identity of components of several individuals, attributable (syst.) to common ancestry; homology avatar : (tax.) case of recognized homology which (syst.) shows broad phylogenetic continuity (e.g. eye) (= character sensu Sokal and Sneath); homolostratum/homology state : (tax.) specified condition of a homology avatar whose distribution (syst.) enables cladogenetic happenings to be identified (e.g. colour:red/green/blue/etc.) (= character state of Sokal and Sneath); character sensu stricto : (tax.) homolostratum limited to a taxon which (syst.), with hierarchy, identifies chronological sequences of most cladogenetic happenings; taxonomoids : (tax.) mixed group of homolostrata, including yet unknown characters, that identifies a taxon and so (syst.) has same role as characters (= roughly symplesiomorphies); Ante- (Ah) and Post-(Ph) happening characters : (tax.) the hierarchy levels immediately above and below an empty level which (syst.) reveal a cladistic happening (= roughly one usage of synapomorphies and apomorphies). 相似文献
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Isolated closed basins provide a natural laboratory to study the differentiation among wild populations. Here we examined the phylogenetic relationships of the Southern Altiplano populations of Biomphalaria, a genus with medical importance, using nuclear (ITS1, ITS2) and mitochondrial (16S) ribosomal gene markers and a species of Helisoma as outgroup. Phylogenetic trees based on separate and combined analyses show that these populations form a particular lineage within Biomphalaria along with Biomphalaria peregrina (d'Orbigny, 1835) and Biomphalaria oligoza Paraense, 1974. The origin of this clade was estimated to have occurred in the middle Pleistocene. Molecular analyses showed that the nominal species Biomphalaria crequii ( Courty, 1907 ) from the Salar de Ascotán and Biomphalaria costata (Biese, 1951) from the Salar de Carcote, previously synonymized with Biomphalaria andecola (d'Orbigny, 1835) and B. peregrina, respectively, are distinct taxa. Molecular data did not resolve the relationship of Biomphalaria aymara Valdovinos & Stuardo, 1991 from the Isluga swamps to other Biomphalaria species, but confirm that the populations from the Lauca and Huasco basins may represent a distinct undescribed species of Biomphalaria from the Southern Altiplano. Snails examined for trematodes were found to be positive in some Altiplano localities. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 165 , 795–808. 相似文献
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Pampatheres are extinct, large‐bodied cingulates, which share morphological characters with both armadillos and glyptodonts but are considered to be more closely related to the latter. The osteoderm histology of six pampathere taxa was examined and compared to the histology of other cingulate osteoderms. This study investigates the development and functional adaptation of pampathere osteoderms as well as the phylogenetic relationships of the Pampatheriidae within the Cingulata. We found that pampathere osteoderms share a uniform histological organization based on a basic diploe‐like structure. After initial stages of intramembranous growth, metaplastic ossification, that is, the direct incorporation and mineralization of pre‐existing protein fibers, plays an important role in osteoderm development and provides information on various kinds of soft tissue otherwise not preserved. The latest stages of osteoderm growth are dominated by periosteal bone formation especially in the superficial cortex. Movable band osteoderms show regular arrangements of incorporated fibers that may increase the resistance of particularly weak areas against strain. The histological composition of pampathere osteoderms is plesiomorphic in its basic structure but shows a number of derived features. A unique array of Sharpey's fibers that are incorporated into the bone matrix at sutured osteoderm margins is interpreted as a synapomorphy of pampatheres. The arrangement of dermal fibers in the deep and superficial cortexes supports the close relationship between pampatheres and glyptodonts. J. Morphol., 2012. © 2011 Wiley Periodicals, Inc. 相似文献
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Software for calculation of 6 diatom indices and diversity indices has been created for both Macintosh and IBM compatible computers. This software runs with the data base Omnis 5 under Windows 3.0. It includes three taxonomic files: families, genera and species, and an inventories file. Four types of data inputs are possible. It is always possible to operate simulations and to carry out investigations with simple or combined characters. All files and results of investigations can be listed in different ways. This data base is compatible with both word processing and spreadsheet systems. 相似文献
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植物系统和进化生物学旨在探讨植物物种多样性的起源、多样化及其进化的机制, 是综合性越来越强的研究领域。2017年在深圳召开的第19届国际植物学大会(IBC 2017)为中国学者提供了一次难得的展示自身实力的机会和舞台, 同时也极大地推动了中国植物系统与进化生物学领域的研究。值此大会召开5周年之际, 本文拟就中国系统和进化生物学领域近年来取得的主要进展和突破做一简要回顾, 以帮助读者了解中国植物系统和进化研究的发展态势, 并在此基础上展望未来该领域的发展趋势以及面临的机遇和挑战。在过去5年中, 中国学者在植物系统与进化生物学领域的各个方面均取得了令人鼓舞的成绩和突破, 涉及植物起源和物种多样性格局的演变、植物分类和系统发生重建、物种形成和适应性进化、种间互作和协同进化、新性状的起源及其进化发育机制、植物多倍化的机制和多倍体进化、物种濒危机制和物种保护以及栽培植物的起源和驯化等等。这些研究成果不仅在数量上而且在质量上有显著提升, 受到国际学界的广泛关注, 意味着中国学者已经成为国际该领域研究的重要力量, 并将在国际植物系统和进化研究领域发挥更大的作用。 相似文献
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Dormant life stages are important strategies for many aquatic organisms. The formation of resting stages will provide a refuge from unfavourable conditions in the water column, and their successive accumulation in the benthos will constitute a genetic reservoir for future planktonic populations. We have determined the genetic structure of a common bloom‐forming diatom, Skeletonema marinoi, in the sediment and the plankton during spring, summer and autumn two subsequent years (2007–2009) in Gullmar Fjord on the Swedish west coast. Eight polymorphic microsatellite loci were used to assess the level of genetic differentiation and the respective gene diversity of the two different habitats. We also determined the degree of genetic differentiation between the seed banks inside the fjord and the open sea. The results indicate that Gullmar Fjord has one dominant endogenous population of S. marinoi, which is genetically differentiated from the open sea population. The fjord population is encountered in the plankton and in the sediment. Shifts from the dominant population can happen, and in our study, two genetically differentiated plankton populations, displaying reduced genetic diversity, occurred in September 2007 and 2008. Based on our results, we suggest that sill fjords maintain local long‐lived and well‐adapted protist populations, which continuously shift between the planktonic and benthic habitats. Intermittently, short‐lived and mainly asexually reproducing populations can replace the dominant population in the water column, without influencing the genetic structure of the benthic seed bank. 相似文献
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人兽冲突是生物多样性保护的重要研究主题,合理的损害补偿有助于野生动物可持续保护及管理。为探究太行山东北部区域野生动物损害及损害补偿,于2019年与2020年7—9月对区域内主要肇事野生动物(野猪Sus scrofa和狗獾Meles leucurus)进行了种群及损害调查;2021年7—8月基于访谈,对区域的损害赔偿及社区的受偿意愿进行了量化计测和分析。结果表明,太行山东北部区域的野猪(密度为(6.283±1.274)只/km2)及狗獾(密度为(4.855±1.610)只/km2)种群较大,对区域内的农业生产带来了较大损害,且肇事频率呈上升趋势;已有的防控手段效果有限,当地社区对野生动物保护支持度较高,但对肇事动物保护的态度相对消极;区域内的野生动物损害补偿已普遍施行,有效补偿了受损农户的部分经济损失,但也存在补偿覆盖不全面、补偿标准模糊及补偿数额偏低等问题。当地农户的受偿意愿((10962.60±1751.55)元/hm2)与其文化程度、损害补偿满意度和野生动物保护态度负相关,与保护政策支持度正相关。根据调研结果,建议加... 相似文献
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Integrative taxonomy of calcareous sponges (subclass Calcinea) from the Peruvian coast: morphology,molecules, and biogeography
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Fernanda Azevedo Báslavi Cóndor‐Luján Philippe Willenz Eduardo Hajdu Yuri Hooker Michelle Klautau 《Zoological Journal of the Linnean Society》2015,173(4):787-817
Understanding of evolution and systematics of Calcarea (Porifera) have not yet met a corresponding increase in the knowledge of diversity and distribution of these sponges in several parts of the world. Peru is an emblematic example of this lack of taxonomic knowledge, as only three shallow‐water species of sponges have hitherto been reported from its 3000 km coast. With the aim of studying sponges of Peru, an integrative taxonomy approach (morphology, molecules, and biogeography) was used in order to achieve sound species identifications. The first findings of Peruvian calcareous sponges are presented here. Eight species are described in the subclass Calcinea, of which five are new to science. The retrieved biogeographical patterns are either locally endemic, widespread, or discontinuous over large areas. Clathrina antofagastensis was previously known from Chile, while C. aurea and Ernstia tetractina had been reported from the Atlantic (Brazil), and thus represent the first genetically confirmed tropical amphi‐American distributions of species not yet found on both sides of the Isthmus of Panama. Our results reveal a richer Tropical East Pacific sponge fauna than the Warm Temperate South‐Eastern Pacific one. © 2015 The Linnean Society of London 相似文献
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Cathucia F. Andriamihaja Alemao Botomanga Chantal Misandeau Aro V. Ramarosandratana Michel Grisoni Denis Da Silva Thierry Pailler Vololoniaina H. Jeannoda Pascale Besse 《植物分类学报:英文版》2023,61(1):80-98
The leafless Vanilla species complex from the South-West Indian Ocean (SWIO) region has long been a taxonomic challenge, due to limited patterns of morphological differentiation and an absence of variation within chloroplast sequences. This complex includes seven known morphospecies: V. madagascariensis, V. bosseri, V. decaryana, and V. perrieri endemic to Madagascar, V. humblotii presumed as endemic to the Comoros Archipelago, but also present in Madagascar, V. roscheri from the East African coast, and V. phalaenopsis endemic to Seychelles. A previous population genetic study using microsatellite markers allowed us to distinguish, in addition to the five recognized Malagasy taxa, two other genetic clusters present in the East of the island. An integrative taxonomy approach was therefore conducted by combining microsatellite and morphological data used in the previous study with new data sets, and by adding ITS sequencing data, to validate the taxonomic level of these Malagasy genetic clusters and unravel phylogenetic relationships between SWIO species. As a result, based on phylogenetic, genotypic and morphological evidence, nine species were discriminated in the SWIO region, including seven in Madagascar, with two new eastern species. The leafless Vanilla group originated and diversified in Madagascar, from an ancestor of African descent, with three subsequent independent colonization events from Madagascar to the other territories of SWIO within the two main lineages (white versus yellow flower species). The new Malagasy species, V. allorgeae Andriamihaja & Pailler sp. nov., and V. atsinananensis Andriamihaja & Pailler sp. nov., are described and a new identification key is proposed. 相似文献
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Arvicanthis is an African murid, found throughout sub-Saharan Africa, Sudan and Egypt. Although in the past 10 years several studies have been carried out to assess its systematics, there is still a need for a general revision of the genus. In this study the morphometric relationships between 71 populations throughout the range were investigated. A three-dimensional geometric morphometric approach was used to assess differences in the size and shape of the skull. These were related to the different biogeographical domains characterizing the range of the genus and to molecular and karyotypic phylogenies. Results agree only in part with phylogeny, and show a close relationship with the environmental backgrounds of each species. It is therefore suggested that the adaptation of Arvicanthis to local environment has played an important role in the phenotypic evolution of the skull. This leads to problems in taxonomic definitions based on morphometrics, which should not be used without comparison with other independently derived characters such as the DNA and the karyotype. 相似文献
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Abstract: Eleven randomly chosen outcrops in the Miocene Pakhna Formation of Cyprus were sampled for holoplanktonic Mollusca. Four species of Heteropoda were found, and 24 of Pteropoda, a substantial increase from the two species recorded until now from the Miocene of Cyprus. One pteropod species, Peracle charlotteae sp. nov. (Gastropoda, Pseudothecosomata), is introduced. Age assignments based on holoplanktonic molluscs for the 11 localities are as follows: Langhian (Alassa 1–4), (Serravallian?) Tortonian to Messinian (Episkopi 1), Tortonian (Agios Tychon, Tokhni and the Maroni Marlstone of Khirokitia 1–2) and Tortonian to Early Messinian (Episkopi 2). These age determinations in some cases are at odds with those from previous publications based on calcareous nannofossils and Foraminifera. The sediments underlying the Amathus Channel outcrop yielded insufficient fauna for definitive dating, but we suggest are younger than Late Serravallian. At some localities, particularly in the Alassa area, pteropod assemblages are strongly variable on a bed‐by‐bed basis, and this offers possibilities for future refined biostratigraphical interpretations. This is the first substantial holoplanktonic mollusc fauna described from the eastern Mediterranean basin and allows correlation with assemblages in the central Mediterranean and elsewhere. 相似文献
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J. W. Wägele 《Journal of Zoological Systematics and Evolutionary Research》1995,33(3-4):42-47
A review of the fundamental difference between single molecular-sequence positions, or numerical characters, and complex morphological characters is the subject of this study. It has been found that transformation series of single complex structures contain enough information to allow a priori determination of character order and that rooting of a dendrogram is possible without out-group comparison, while trees based on less-informative characters can usually only be rooted with out-group comparison. Furthermore, the quality of total information used is decisive in discriminating between hypotheses of relationships. Numerical methods for the inference of phylogenies have been found to be useful for high numbers of characters that have only a low information content, while the Hennigian procedure seems to be preferable for complex characters.
Ein fundamentaler Unterschied zwischen der einzelnen Sequenzposition oder auch numerischen Merkmalen und komplexen morphologischen Merkmalen ist ihr Informationsgehalt. Merkmalsreihen komplexer Strukturen enthalten meist genügend Information, um a priori die Bestimmung der Lesrichtung zu ermöglichen. Die Feststellung des Ursprunges eines Dendrogramms ist somit ohne kladistischen Außengruppenvergleich möglich, während Bäume (Topologien), die auf wenig informativen Merkmalen beruhen, allgemein nur mit dem kladistischen Außengruppenvergleich 'gewurzelt' werden können. Die Qualität der insgesamt verwendeten Information ist entscheidend für die Wahl zwischen alternativen Verwandtschaftshypothesen. Numerische Methoden der Rekonstruktion der Phylogenese sind nützlich bei Verwendung einer gro β en Zahl informationsarmer Merkmale; das Hennigsche Verfahren ist für komplexe Merkmale vorzuziehen. 相似文献
Zusammenfassung
Ein fundamentaler Unterschied zwischen der einzelnen Sequenzposition oder auch numerischen Merkmalen und komplexen morphologischen Merkmalen ist ihr Informationsgehalt. Merkmalsreihen komplexer Strukturen enthalten meist genügend Information, um a priori die Bestimmung der Lesrichtung zu ermöglichen. Die Feststellung des Ursprunges eines Dendrogramms ist somit ohne kladistischen Außengruppenvergleich möglich, während Bäume (Topologien), die auf wenig informativen Merkmalen beruhen, allgemein nur mit dem kladistischen Außengruppenvergleich 'gewurzelt' werden können. Die Qualität der insgesamt verwendeten Information ist entscheidend für die Wahl zwischen alternativen Verwandtschaftshypothesen. Numerische Methoden der Rekonstruktion der Phylogenese sind nützlich bei Verwendung einer gro β en Zahl informationsarmer Merkmale; das Hennigsche Verfahren ist für komplexe Merkmale vorzuziehen. 相似文献
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We present a comprehensively sampled three‐gene phylogeny of the monophyletic Forcipulatacea, one of three major lineages within the crown‐group Asteroidea. We present substantially more Southern Hemisphere and deep‐sea taxa than were sampled in previous molecular studies of this group. Morphologically distinct groups, such as the Brisingida and the Zoroasteridae, are upheld as monophyletic. Brisingida is supported as the derived sister group to the Asteriidae (restricted), rather than as a basal taxon. The Asteriidae is paraphyletic, and is broken up into the Stichasteridae and four primary asteriid clades: (1) a highly diverse boreal clade, containing members from the Arctic and sub‐Arctic in the Northern Hemisphere; (2) the genus Sclerasterias; (3) and (4) two sister clades that contain asteriids from the Antarctic and pantropical regions. The Stichasteridae, which was regarded as a synonym of the Asteriidae, is resurrected by our results, and represents the most diverse Southern Hemisphere forcipulatacean clade (although two deep‐sea stichasterid genera occur in the Northern Hemisphere). The Labidiasteridae is artificial, and should be synonymized into the Heliasteridae. The Pedicellasteridae is paraphyletic, with three separate clades containing pedicellasterid taxa emerging among the basal Forcipulatacea. Fossils and timing estimates from species‐level phylogeographic studies are consistent with prior phylogenetic hypotheses for the Forcipulatacea, suggesting diversification of basal taxa in the early Mesozoic, with some evidence for more widely distributed ranges from Cretacous taxa. Our analysis suggests a hypothesis of an older fauna present in the Antarctic during the Eocene, which was succeeded by a modern Antarctic fauna that is represented by the recently derived Antarctic Asteriidae and other forcipulatacean lineages. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 162 , 646–660. 相似文献
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PER SUNDBERG 《Zoological Journal of the Linnean Society》1985,85(3):247-266
The applicability of numerical methods to the taxonomy of the Phylum Nemertea is assessed for a group of hoplonemertean species. The classifications obtained from various cluster and ordination methods are evaluated with reference to their predictability, i.e. the number of character or character states that can be predicted about species A knowing that it belongs to class a. 相似文献
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Fabio Gaiger 《法国昆虫学会纪事》2013,49(1):47-57
The utility of the female genitalia and associated sclerites (tergite and sternite VIII) in the systematics of the Curculionidae is discussed. Examples from the tribe Entimini (Entiminae) and subtribe Hylobiina (Molytinae: Hylobiini) are given. The female characters prove to be informative for establishing the phylogenetic relationships among genera of Entimini. They are essential in determining species groups within the genus Arniticus Pascoe, Hylobiina. 相似文献