首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.

Background

The use of phylogenetic information in community ecology and conservation has grown in recent years. Two key issues for community phylogenetics studies, however, are (i) low terminal phylogenetic resolution and (ii) arbitrarily defined species pools.

Methodology/principal findings

We used three DNA barcodes (plastid DNA regions rbcL, matK, and trnH-psbA) to infer a phylogeny for 527 native and naturalized trees of Puerto Rico, representing the vast majority of the entire tree flora of the island (89%). We used a maximum likelihood (ML) approach with and without a constraint tree that enforced monophyly of recognized plant orders. Based on 50% consensus trees, the ML analyses improved phylogenetic resolution relative to a comparable phylogeny generated with Phylomatic (proportion of internal nodes resolved: constrained ML = 74%, unconstrained ML = 68%, Phylomatic = 52%). We quantified the phylogenetic composition of 15 protected forests in Puerto Rico using the constrained ML and Phylomatic phylogenies. We found some evidence that tree communities in areas of high water stress were relatively phylogenetically clustered. Reducing the scale at which the species pool was defined (from island to soil types) changed some of our results depending on which phylogeny (ML vs. Phylomatic) was used. Overall, the increased terminal resolution provided by the ML phylogeny revealed additional patterns that were not observed with a less-resolved phylogeny.

Conclusions/significance

With the DNA barcode phylogeny presented here (based on an island-wide species pool), we show that a more fully resolved phylogeny increases power to detect nonrandom patterns of community composition in several Puerto Rican tree communities. Especially if combined with additional information on species functional traits and geographic distributions, this phylogeny will (i) facilitate stronger inferences about the role of historical processes in governing the assembly and composition of Puerto Rican forests, (ii) provide insight into Caribbean biogeography, and (iii) aid in incorporating evolutionary history into conservation planning.  相似文献   

2.
The megadiverse genus Carex (c. 2000 species, Cyperaceae) has a nearly cosmopolitan distribution, displaying an inverted latitudinal richness gradient with higher species diversity in cold‐temperate areas of the Northern Hemisphere. Despite great expansion in our knowledge of the phylogenetic history of the genus and many molecular studies focusing on the biogeography of particular groups during the last few decades, a global analysis of Carex biogeography and diversification is still lacking. For this purpose, we built the hitherto most comprehensive Carex‐dated phylogeny based on three markers (ETS–ITS–matK), using a previous phylogenomic Hyb‐Seq framework, and a sampling of two‐thirds of its species and all recognized sections. Ancestral area reconstruction, biogeographic stochastic mapping, and diversification rate analyses were conducted to elucidate macroevolutionary biogeographic and diversification patterns. Our results reveal that Carex originated in the late Eocene in E Asia, where it probably remained until the synchronous diversification of its main subgeneric lineages during the late Oligocene. E Asia is supported as the cradle of Carex diversification, as well as a “museum” of extant species diversity. Subsequent “out‐of‐Asia” colonization patterns feature multiple asymmetric dispersals clustered toward present times among the Northern Hemisphere regions, with major regions acting both as source and sink (especially Asia and North America), as well as several independent colonization events of the Southern Hemisphere. We detected 13 notable diversification rate shifts during the last 10 My, including remarkable radiations in North America and New Zealand, which occurred concurrently with the late Neogene global cooling, which suggests that diversification involved the colonization of new areas and expansion into novel areas of niche space.  相似文献   

3.
Methane formation and oxidation by prokaryotes   总被引:1,自引:0,他引:1  
The review deals with systematization and generalization of new information concerning the phylogenetic and functional diversity of prokaryotes involved in the methane cycle. Methane is mostly produced by methanogenic archaea, which are responsible for the terminal stage of organic matter decomposition in a number of anoxic ecotopes. Although phylogeny, physiology, and biochemistry of methanogens have been extensively studied, important discoveries were made recently. Thus, members of deep phylogenetic lineages within the Euryarchaeota phylum (Methanomassiliicoccales, “Candidatus Methanofastidiosa,” “Methanonatronarchaeia”) and even outside it (“Ca. Verstraetearchaeota” and “Ca. Bathyarchaeota”) were reported to carry out methyl-reducing methanogenesis. Moreover, evidence was obtained on aerobic methane production by marine heterotrophic bacteria, which demethylate polysaccharide esters of methylphosphonic acid. Methanotrophic microorganisms oxidize methane both aerobically and anaerobically, decreasing significantly the release of this greenhouse gas into the atmosphere. In the presence of oxygen methane is oxidized by methanotrophic members of Alpha- and Gammaproteobacteria, as well as by Verrucomicrobia. Methanotrophic gammaproteobacteria have been recently revealed in hypoxic and even anoxic environments, where they probably oxidize methane either in a trophic consortium with oxygenic phototrophs and/or methylotrophs or using electron acceptors other than oxygen. Anaerobic methane oxidation has been known for a long time. Sulfat- and nitrate-dependent anaerobic methane oxidation carried out by the ANME archaea via reverse methanogenesis are the best studied processes. While metal-dependent anaerobic methane oxidation is considered possible, the mechanisms and agents responsible for this process have not been reliably identified. Intracellular oxygen production during nitrite-dependent anaerobic methane oxidation was shown for bacteria “Ca. Methylomirabilis oxyfera.” These findings stimulate interest in the processes and microorganisms of the methane cycle.  相似文献   

4.

BACKGROUND

Neuronal activity in cortical areas regulates neurodevelopment by interacting with defined genetic programs to shape the mature central nervous system. Electrical activity is conveyed to sensory cortical areas via intracortical and thalamocortical neurons, and includes oscillatory patterns that have been measured across cortical regions.

OBJECTIVE

In this work, we review the most recent findings about how electrical activity shapes the developmental assembly of functional circuitry in the somatosensory cortex, with an emphasis on interneuron maturation and integration. We include studies on the effect of various neurotransmitters and on the influence of thalamocortical afferent activity on circuit development. We additionally reviewed studies describing network activity patterns.

METHODS

We conducted an extensive literature search using both the PubMed and Google Scholar search engines. The following keywords were used in various iterations: “interneuron”, “somatosensory”, “development”, “activity”, “network patterns”, “thalamocortical”, “NMDA receptor”, “plasticity”. We additionally selected papers known to us from past reading, and those recommended to us by reviewers and members of our lab.

RESULTS

We reviewed a total of 132 articles that focused on the role of activity in interneuronal migration, maturation, and circuit development, as well as the source of electrical inputs and patterns of cortical activity in the somatosensory cortex. 79 of these papers included in this timely review were written between 2007 and 2016.

CONCLUSION

Neuronal activity shapes the developmental assembly of functional circuitry in the somatosensory cortical interneurons. This activity impacts nearly every aspect of development and acquisition of mature neuronal characteristics, and may contribute to changing phenotypes, altered transmitter expression, and plasticity in the adult. Progressively changing oscillatory network patterns contribute to this activity in the early postnatal period, although a direct requirement for specific patterns and origins of activity remains to be demonstrated.
  相似文献   

5.

Main conclusion

Three independent patterns of vein formation in Cyperus involucratus Rottb. were identified based on rare spontaneous interruptions of scape vein development. A number of developmental anomalies of vascular bundles in Cyperus involucratus Rottb. were identified and they include “turnabout”, “absent”, “twins”, “doublet”, amphivasal and various stages of “arrested”. These were used to develop a computer program to explain the three vasculature patterns of the scape of (a) ordered deployment of vascular bundles, (b) arrangement of tissues within vascular bundles and (c) orientation of vascular bundles with respect to stem edge. The computer model is a cell-by-cell determination of cell types and facet states.
  相似文献   

6.

Background

Horizontal gene transfer (HGT) plays a major role in speciation and evolution of bacteria and archaea by controlling gene distribution within an environment. However, information that links HGT to a natural community using relevant population-genetics parameters and spatial considerations is scarce. The Great Salt Lake (Utah, USA) provides an excellent model for studying HGT in the context of biogeography because it is a contiguous system with dispersal limitations due to a strong selective salinity gradient. We hypothesize that in spite of the barrier to phylogenetic dispersal, functional characteristics—in the form of HGT—expand beyond phylogenetic limitations due to selective pressure.

Methodology and Results

To assay the functional genes and microorganisms throughout the GSL, we used a 16S rRNA oligonucleotide microarray (Phylochip) and a functional gene array (GeoChip) to measure biogeographic patterns of nine microbial communities. We found a significant difference in biogeography based on microarray analyses when comparing Sørensen similarity values for presence/absence of function and phylogeny (Student''s t-test; p = 0.005).

Conclusion and Significance

Biogeographic patterns exhibit behavior associated with horizontal gene transfer in that informational genes (16S rRNA) have a lower similarity than functional genes, and functional similarity is positively correlated with lake-wide selective pressure. Specifically, high concentrations of chromium throughout GSL correspond to an average similarity of chromium resistance genes that is 22% higher than taxonomic similarity. This suggests active HGT may be measured at the population level in microbial communities and these biogeographic patterns may serve as a model to study bacteria adaptation and speciation.  相似文献   

7.

Aim

Here I review phylogenetic studies concerning the biogeography of the Marquesas Islands, an oceanic hotspot archipelago in the Pacific Ocean formed <5.5 Ma, and compare patterns (particularly pertaining to colonization and diversification) within the archipelago to those reported from the Hawaiian and Society Islands.

Location

Marquesas Islands, French Polynesia (Pacific Ocean).

Methods

I reviewed 37 phylogenetic studies incorporating Marquesas‐endemic taxa. I asked the following questions: (a) where are the sister‐groups of Marquesas lineages distributed? (b) are Marquesas‐endemic “radiations” monophyletic or polyphyletic? (c) what major between‐island phylogeographic barriers are seen in the Marquesas? (d) what evidence exists for diversification within islands? (e) how old is the Marquesas biota compared to the archipelago's age? Finally, these patterns are compared with those seen in the Society Islands and Hawaii.

Results

Most Marquesan lineages have their closest known relatives on other Pacific plate archipelagos (particularly the Society, Hawaiian, and Austral islands). Most Marquesas‐endemic radiations are found to be monophyletic, and among‐island diversification appears to be common. There is limited evidence for within‐island diversification. Some radiations may be consistent with a weak progression rule in which younger lineages are on younger islands. Crown ages of no Marquesas radiations appear to be older than the age of the archipelago (with one exception).

Main conclusions

Diversification of the Marquesas biota resembles that of the Hawaiian Islands more than that of the Society Islands. Many radiations are monophyletic and some appear to diversify in parallel with the formation of the archipelago.
  相似文献   

8.
Smith ND 《PloS one》2010,5(10):e13354

Background

Debate regarding the monophyly and relationships of the avian order Pelecaniformes represents a classic example of discord between morphological and molecular estimates of phylogeny. This lack of consensus hampers interpretation of the group''s fossil record, which has major implications for understanding patterns of character evolution (e.g., the evolution of wing-propelled diving) and temporal diversification (e.g., the origins of modern families). Relationships of the Pelecaniformes were inferred through parsimony analyses of an osteological dataset encompassing 59 taxa and 464 characters. The relationships of the Plotopteridae, an extinct family of wing-propelled divers, and several other fossil pelecaniforms (Limnofregata, Prophaethon, Lithoptila, ?Borvocarbo stoeffelensis) were also assessed. The antiquity of these taxa and their purported status as stem members of extant families makes them valuable for studies of higher-level avian diversification.

Methodology/Principal Findings

Pelecaniform monophyly is not recovered, with Phaethontidae recovered as distantly related to all other pelecaniforms, which are supported as a monophyletic Steganopodes. Some anatomical partitions of the dataset possess different phylogenetic signals, and partitioned analyses reveal that these discrepancies are localized outside of Steganopodes, and primarily due to a few labile taxa. The Plotopteridae are recovered as the sister taxon to Phalacrocoracoidea, and the relationships of other fossil pelecaniforms representing key calibration points are well supported, including Limnofregata (sister taxon to Fregatidae), Prophaethon and Lithoptila (successive sister taxa to Phaethontidae), and ?Borvocarbo stoeffelensis (sister taxon to Phalacrocoracidae). These relationships are invariant when ‘backbone’ constraints based on recent avian phylogenies are imposed.

Conclusions/Significance

Relationships of extant pelecaniforms inferred from morphology are more congruent with molecular phylogenies than previously assumed, though notable conflicts remain. The phylogenetic position of the Plotopteridae implies that wing-propelled diving evolved independently in plotopterids and penguins, representing a remarkable case of convergent evolution. Despite robust support for the placement of fossil taxa representing key calibration points, the successive outgroup relationships of several “stem fossil + crown family” clades are variable and poorly supported across recent studies of avian phylogeny. Thus, the impact these fossils have on inferred patterns of temporal diversification depends heavily on the resolution of deep nodes in avian phylogeny.  相似文献   

9.
The aim of this work was to study the biodiversity of yeasts isolated from the autochthonous grape variety called “Uva di Troia”, monitoring the natural diversity from the grape berries to wine during a vintage. Grapes were collected in vineyards from two different geographical areas and spontaneous alcoholic fermentations (AFs) were performed. Different restriction profiles of ITS–5.8S rDNA region, corresponding to Saccharomyces cerevisiae, Issatchenkia orientalis, Metschnikowia pulcherrima, Hanseniaspora uvarum, Candida zemplinina, Issatchenkia terricola, Kluyveromyces thermotolerans, Torulaspora delbrueckii, Metschnikowia chrysoperlae, Pichia fermentans, Hanseniaspora opuntiae and Hanseniaspora guilliermondii, were observed. The yeast occurrences varied significantly from both grape berries and grape juices, depending on the sampling location. Furthermore, samples collected at the end of AF revealed the great predominance of Saccharomyces cerevisiae, with a high intraspecific biodiversity. This is the first report on the population dynamics of ‘cultivable’ microbiota diversity of “Uva di Troia” cultivar from the grape to the corresponding wine (“Nero di Troia”), and more general for Southern Italian oenological productions, allowing us to provide the basis for an improved management of wine yeasts (with both non-Saccharomyces and Saccharomyces) for the production of typical wines with desired unique traits. A certain geographical-dependent variability has been reported, suggesting the need of local based formulation for autochthonous starter cultures, especially in the proportion of the different species/strains in the design of mixed microbial preparations.  相似文献   

10.
11.
Molecular phylogenetic analyses conducted over the past 15 yr have consistently had difficulties resolving relationships among the cetacean species in the subfamily Delphininae. In addition, paraphyly of the genera Tursiops and Stenella in these molecular phylogenies has been a recurrent problem since the first appearance of such a phylogeny in 1999, suggesting that these genera do not accurately reflect the evolutionary relationships of the species they contain. Morphological analyses have not resolved the issues. The genera in Delphininae originated in the 19th Century on questionable morphological grounds. The species were nearly all originally described in the genus Delphinus of Linnaeus. Recent molecular phylogenies based on various mitochondrial and nuclear DNA markers have suggested a wide range of possible relationships among these taxa, and several authors have suggested synonymizing all the taxa (Lagenodelphis, Stenella, Sousa, and Tursiops) under Delphinus. Until molecular and/or morphological analyses adequately sort out relationships in this very recently radiated group, one possible solution indeed would be to merge all the delphinine genera with Delphinus. Implications of such a move and alternatives are discussed.
Editor's Note: Papers from past Norris Award winners have primarily been a revised or reduced version of the actual presentation given as a plenary talk at the biennial conference. Dr. Perrin requested being allowed to take a topic from his presentation and expand on it to present a set of ideas in the form of an essay that could pass the rigors of the peer‐review process. As a result, this Norris Award paper has undergone peer‐review and has taken longer than usual for a Norris Award paper to appear in the journal following its presentation at the biennial conference. It also has co‐authors, with varying opinions on the issues discussed in the essay, to cover appropriately and more thoroughly those components of the paper that required additional expertise. I believe this approach has produced an excellent, thought‐provoking essay and is an approach that should be available to future Norris Award winners if they so choose to take it. Since this essay is meant to elicit dialogue, comments are welcome and will be considered for publication in Letters to the Editor.
  相似文献   

12.
The phylogeny of phagotrophic euglenids is widely based on nuclear small subunit ribosomal DNA (18S rDNA) sequence data, but most analyses suffer from weakness in statistical support regarding the “connecting backbone” between monophyletic clades. Moreover, the position of Entosiphon has remained unclear. Testing the 18S rDNA capability for a phylogeny of phagotrophic euglenids, we isolated sequences of Peranema sp. and Ploeotia edaphica and utilized secondary structure data as a prerequisite for recognition of homologous positions. We found a unique, clade-specific nucleotide substitution in the deduced 18S rDNA helix 44. Since our 18S rDNA phylogenies could only in part resolve positions of phagotrophic lineages, but did not verify that of Entosiphon, we investigated the phagotrophic key taxa Peranema trichophorum, Petalomonas cantuscygni, Ploeotia costata, and Entosiphon sulcatum ultrastructurally. Additionally, we explored the presence or absence of the euglenid reserve carbohydrate paramylon by specific staining with monoclonal anti-β-1,3-glucan antibodies. Paramylon was found to be clearly present in P. trichophorum and E. sulcatum, but was absent in Pt. cantuscygni and Pl. costata. Combined results of our molecular, ultrastructural, and immunocytochemical investigations suggest that Entosiphon sulcatum is the sister taxon of a monophyletic euglenid crown clade, characterized by a helical pellicle, which we propose to rename. This phylogenetic affiliation is confirmed by a clade-specific primary absence of the unique nucleotide substitution in helix 44 and by the common presence of paramylon.  相似文献   

13.
A new barklouse species belonging to the Trichadenotecnum s.str. clade (Psocodea: “Psocoptera”: Psocidae) was described from southeastern Brazil (Minas Gerais state). This locality is highly isolated (about 3400 km) from the closest known distributional range of this clade. It also represents the southernmost distributional record of Trichadenotecnum s.str. Phylogenetic placement of the species and biogeography of Neotropical Trichadenotecnum were briefly discussed. Trichadenotecnum punctipenne New, 1972 described from Brazil was synonymized with Trichadenotecnum pardus Badonnel, 1955.  相似文献   

14.
The southeastern United States (U.S.) has experienced dynamic climatic changes over the past several million years that have impacted species distributions. In many cases, contiguous ranges were fragmented and a lack of gene flow between allopatric populations led to genetic divergence and speciation. The Southern Red-backed Salamander, Plethodon serratus, inhabits four widely disjunct regions of the southeastern U.S.: the southern Appalachian Mountains, the Ozark Plateau, the Ouachita Mountains, and the Southern Tertiary Uplands of central Louisiana. We integrated phylogenetic analysis of mitochondrial DNA sequences (1399 base pairs) with ecological niche modeling to test the hypothesis that climate fluctuations during the Pleistocene drove the isolation and divergence of disjunct populations of P. serratus. Appalachian, Ozark, and Louisiana populations each formed well-supported clades in our phylogeny. Ouachita Mountain populations sorted into two geographically distinct clades; one Ouachita clade was sister to the Louisiana clade whereas the other Ouachita clade grouped with the Appalachian and Ozark clades but relationships were unresolved. Plethodon serratus diverged from its sister taxon, P. sherando, ~5.4 million years ago (Ma), and lineage diversification within P. serratus occurred ~1.9–0.6 Ma (Pleistocene). Ecological niche models showed that the four geographic isolates of P. serratus are currently separated by unsuitable habitat, but the species was likely more continuously distributed during the colder climates of the Pleistocene. Our results support the hypothesis that climate-induced environmental changes during the Pleistocene played a dominant role in driving isolation and divergence of disjunct populations of P. serratus.  相似文献   

15.
Regier JC  Zwick A 《PloS one》2011,6(8):e23408

Background

This study aims to investigate the strength of various sources of phylogenetic information that led to recent seemingly robust conclusions about higher-level arthropod phylogeny and to assess the role of excluding or downweighting synonymous change for arriving at those conclusions.

Methodology/Principal Findings

The current study analyzes DNA sequences from 68 gene segments of 62 distinct protein-coding nuclear genes for 80 species. Gene segments analyzed individually support numerous nodes recovered in combined-gene analyses, but few of the higher-level nodes of greatest current interest. However, neither is there support for conflicting alternatives to these higher-level nodes. Gene segments with higher rates of nonsynonymous change tend to be more informative overall, but those with lower rates tend to provide stronger support for deeper nodes. Higher-level nodes with bootstrap values in the 80% – 99% range for the complete data matrix are markedly more sensitive to substantial drops in their bootstrap percentages after character subsampling than those with 100% bootstrap, suggesting that these nodes are likely not to have been strongly supported with many fewer data than in the full matrix. Data set partitioning of total data by (mostly) synonymous and (mostly) nonsynonymous change improves overall node support, but the result remains much inferior to analysis of (unpartitioned) nonsynonymous change alone. Clusters of genes with similar nonsynonymous rate properties (e.g., faster vs. slower) show some distinct patterns of node support but few conflicts. Synonymous change is shown to contribute little, if any, phylogenetic signal to the support of higher-level nodes, but it does contribute nonphylogenetic signal, probably through its underlying heterogeneous nucleotide composition. Analysis of seemingly conservative indels does not prove useful.

Conclusions

Generating a robust molecular higher-level phylogeny of Arthropoda is currently possible with large amounts of data and an exclusive reliance on nonsynonymous change.  相似文献   

16.
A new Dienia type of the embryogenesis of orchid plants differing from the Liparis type, earlier observed for the tribe Malaxideae, has been described in Dienia ophrydis (J. Köenig) Seidenf. (Orchidaceae). The Dienia-type embryogenesis is characterized by the following features: (1) development of a single-celled suspensor formed by a cb-derivative, (2) linear arrangement of embryo cells at the tetrad stage, (3) atypical origin of some tiers, and (4) no divisions of the ci and cb cells. A hypothesis about the convergent similarity between the Dienia and Caryophyllaceae types of embryogenesis has been proposed. A number of embryo sac and embryo structures typical for D. ophrydis, including “petassum,” “fitting,” and “suspensor mantle,” have been first described. A “petassum” represents the remains of cell walls of the pollen tube and probably the filamentous apparatus of synergids sealing the micropyle side of a fertilized embryo sac. The sole suspensor cell has a special appendix (“fitting”), which connects it to the embryo. The suspensor and the fitting are surrounded by a special envelope (“suspensor mantle”), which does not cover the basal cell of the embryo (ci).  相似文献   

17.
The genus Tettigonia includes 26 species distributed in the Palaearctic region. Though the Green Bush-crickets are widespread in Europe and common in a variety of habitats throughout the Palaearctic ecozone, the genus is still in need of scientific attention due to the presence of a multitude of poorly explored taxa. In the present study, we sought to clarify the evolutionary relationships of Green Bush-crickets and the composition of taxa occurring in the Western Palaearctic. Based on populations from 24 disjunct localities, the phylogeny of the group was estimated using sequences of the cytochrome oxidase subunit I (COI) and the internal transcribed spacers 1 and 2 (ITS1 and ITS2). Morphological and acoustic variation documented for the examined populations and taxa was interpreted in the context of phylogenetic relationships inferred from our genetic analyses. The trees generated in the present study supported the existence of three main lineages: “A”—composed of all sampled populations of Tettigonia viridissima and the Tettigonia vaucheriana complex, “B”—comprising Tettigonia caudata, Tettigonia uvarovi, and the Tettigonia armeniaca complex, and “C”—consisting of Tettigonia cantans. The present study provides the first phylogenetic foundation for reviewing the systematics of Tettigonia (currently classified mostly according to morphological characteristics), proposing seven new synonymies.  相似文献   

18.
The Lophocoleaceae-Plagiochilaceae-Brevianthaceae clade is a largely terrestrial, subcosmopolitan lineage of jungermannialean leafy liverworts that may include significantly more than 1000 species. Here we present the most comprehensively sampled phylogeny available to date based on the nuclear ribosomal internal transcribed spacer region and the chloroplast markers rbcL and rps4 of 372 accessions. Brevianthaceae (consisting of Brevianthus and Tetracymbaliella) form a sister relationship with Lophocoleaceae; this lineage is in turn sister to Plagiochilaceae. Plagiochila is resolved monophyletic subsequent to exclusion of Plagiochila radiculosa; this species is placed in a new genus Cryptoplagiochila. Chiastocaulon and a polyphyletic Acrochila nest in Plagiochilion; these three genera are united under Chiastocaulon to include the Plagiochilaceae species with dominating or exclusively ventral branching. The generic classification of the Lophocoleaceae is still unresolved. We discuss alternative approaches to obtain strictly monophyletic genera by visualizing their consistence with the obtained consensus topology. The presented phylogeny will serve as a basis for follow-up studies including several thousand accessions. These studies will enable revision of current hypotheses on species diversity and distribution of Lophocoleaceae-Plagiochilaceae-Brevianthaceae and allow for a reconstruction of their evolution in time and space.  相似文献   

19.
In “Oscillatoriales” cyanobacteria (Cyanophyceae), relatively simple and uniform morphology superimposes on high genetic diversity that impedes reliable identification. The system of Cyanobacteria set forth in Bergey’s Manual of Systematic Bacteriology-2001/Systematics of Archaea and Bacteria-2015 deals with operational taxa—form-genera (“larger” genera represented by strains) unlike true cyanophycean genera represented by species. Form-genera were established on morphological criteria shared with Cyanophyceae, although they were typified by Pasteur Culture Collection (PCC) strains. Despite being important in determinative cyanobacteriology, old diagnoses of form-genera should be reappraised because, in them: (i) vague and/or ephemeral morphological characters are considered taxonomically significant; (ii) phylogenetic character, such as 16S rRNA gene sequence (16S) is missing. We identified 32 “Oscillatoriales” strains from CALU collection (St. Petersburg University, Russia) basing on core morphology traits, 16S of PCC type strains, and 16S from GenBank database. We proposed that, in experimentally oriented and ecology oriented studies, unequivocal identification can be attained via triple match: streamlined form-genus diagnosis— 16S of PCC reference strain—GenBank most similar 16S. Additionally, we traced the phylogeny of “Oscillatoriales” form-genera via 16S clustering and HIP1 fingerprinting, and suggested that these operational taxa should be replaced with monophyletic assemblages. Nucleotide sequence data reported are available in the GenBank database under the accession numbers KX263921?KX263950.  相似文献   

20.

Background

Order Charadriiformes (shorebirds) is an ideal model group in which to study a wide range of behavioural, ecological and macroevolutionary processes across species. However, comparative studies depend on phylogeny to control for the effects of shared evolutionary history. Although numerous hypotheses have been presented for subsets of the Charadriiformes none to date include all recognised species. Here we use the matrix representation with parsimony method to produce the first fully inclusive supertree of Charadriiformes. We also provide preliminary estimates of ages for all nodes in the tree.

Results

Three main lineages are revealed: i) the plovers and allies; ii) the gulls and allies; and iii) the sandpipers and allies. The relative position of these clades is unresolved in the strict consensus tree but a 50% majority-rule consensus tree indicates that the sandpiper clade is sister group to the gulls and allies whilst the plover group is placed at the base of the tree. The overall topology is highly consistent with recent molecular hypotheses of shorebird phylogeny.

Conclusion

The supertree hypothesis presented herein is (to our knowledge) the only complete phylogenetic hypothesis of all extant shorebirds. Despite concerns over the robustness of supertrees (see Discussion), we believe that it provides a valuable framework for testing numerous evolutionary hypotheses relating to the diversity of behaviour, ecology and life-history of the Charadriiformes.
  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号