Genetic structure of Eurasian and North American Leymus (Triticeae) wildryes assessed by chloroplast DNA sequences and AFLP profiles

Leymus is a genomically defined allopolyploid of genus Triticeae with two distinct subgenomes. Chloroplast DNA sequences of Eurasian and North American species are distinct and polyphyletic. However, phylogenies derived from chloroplast and nuclear DNA sequences are confounded by polyploidy and lack of polymorphism among many taxa. The AFLP technique can resolve phylogenetic relationships between closely related species, with a curvilinear relationship expected between the proportion of shared bands and nucleotide substitution rate (D), up to about 0.100 D. The objective of this study was to compare D and phylogenetic relationships among 16 Leymus taxa, based on chloroplast DNA sequences and multi-locus AFLP genotypes. Estimates of chloroplast D between taxa were 0.002 and 0.013 within and among continental regions, respectively. Estimates of AFLP D between taxa were 0.076 and 0.093 compared within and between continental regions, respectively, versus 0.024 within taxa. Bayesian and neighbor-joining cluster analyses effectively separated all AFLP genotypes by species, but showed that North American L. ambiguus is a hybrid species with nearly equal contributions from sympatric L. cinereus and L. salinus taxa. Two hierarchical AFLP clades, containing six North American taxa and four Eurasian taxa, had more than 98% bootstrap confidence with 0.071 and 0.055 D among taxa. Three other Eurasian taxa clustered with 79% and 89% confidence, with up to 0.79 D between taxa. These estimates provide benchmarks for phylogenetic comparisons of AFLP profiles, but three taxa could not be reliably grouped, which may reflect concurrent radiation of multiple lineages or lack of homologous AFLP characters caused by a high D.     

Systematic biostratigraphy: A solution to problematic classification systems in biostratigraphy

Systematic biostratigraphy is based on the exclusive use of monophyletic marker taxa. Non-monophyletic, or artificial, marker taxa have been shown to change biostratigraphic correlations, a situation that can be rectified by using systematics to ensure that marker taxa are monophyletic or natural. Both hypothetical and real examples demonstrate the validity of the methodology. The foraminiferal genera Praemurica and Parvularugoglobigerina are examples of non-monophyletic marker taxa. Cladistic results permit the reclassification of both genera, and a revision of foraminiferal biostratigraphy. Systematic biostratigraphy ensures the use of monophyletic marker taxa, preventing artificial classifications from hindering biostratigraphic correlations and producing more accurate, and stable, biostratigraphic zonations.     

Differential dissolution of upper Cretaceous deep-sea benthonic foraminifers from the Angola Basin,South Atlantic Ocean

Material from the Deep Sea Drilling Project (DSDP) Site 527 from the Angola Basin, South Atlantic Ocean, has been analyzed to determine whether Upper Cretaceous benthonic foraminiferal taxa are differentially sensitive to calcite dissolution, and, if so, to rank their order of susceptibility. Two regimes of dissolution, established on the basis of the degree of planktonic foraminiferal fragmentation, representing stronger and less prominent dissolution within the section studied, were used as a framework for reference. A total of 60 calcareous and eight agglutinated benthonic foraminiferal taxa were identified at the species or genus level; of these, twenty-three calcareous and five agglutinated taxa were selected for the dissolution study. Relative abundance of each of the various taxa was tested statistically, using t-test, between dissolution regimes to assess the significance of the change induced by increased dissolution.Nuttallides truempyi andNeoeponides sp. intermediate form are interpreted as resistant to dissolution.Pullenia spp.,Alabamina sp. a,Anomalina sp. a,Praebulimina sp. fusiform, andNuttallinella sp. a are susceptible to dissolution. The majority of the taxa (16 in number) are unaffected by dissolution because they show no change between dissolution regimes. Among the agglutinated taxaGaudryina pyramidata is resistant to dissolution, whereas the remaining four taxa are unaffected by dissolution. At the level of superfamilies, one calcareous superfamily (Discorbacea) is resistant, two (Orbitoidacea and Cassidulinacea) are unaffected, and two (Nodosariacea and Buliminacea) are susceptible to dissolution.     

Leaflet secretory structures of five taxa of the genus Zornia J.F. Gmel. (Leguminosae, Papilionoideae, Dalbergieae) and their systematic significance

A survey of the secretory structures of leaflets has been carried out for five taxa of the genus Zornia J.F. Gmel. to assess possible taxonomic value of the glands, taking into account that these taxa, Zornia curvata Mohlenbr., Z. gemella Willd. ex Vogel, Z. glabra Desv., Z. latifolia Sm. and Z. reticulata Sm., have overlapping diagnostic characters. The leaflet secretory structures of the five studied taxa of Zornia were mucilage epidermis, mucilage cavities, and idioblasts secreting phenolic compounds. Mucilage epidermis is found in all five aforementioned taxa. Mucilage cavities are observed on both epidermal surfaces of the leaflets in four taxa, the exception being Z. glabra, whose cavities occur only on the abaxial surface. Idioblasts secreting phenolic compounds were detected only in the mesophyll of Z. latifolia and Z. reticulata. The joint occurrence of mucilage epidermis with mucilage cavities seems to be of unifying value for the five taxa analyzed. The position of mucilage cavities and the occurrence of secretory idioblasts in the mesophyll of the leaflets are of diagnostic value, providing a key to enable identification of the taxa studied. This study reveals that the secretory structures provide important information in support of systematic studies of the Leguminosae. In relation to the five taxa of Zornia studied, current results suggest recognition of four species: Z. curvata, Z. glabra, Z. latifolia, and Z. reticulata.     

Cytological and reproductive differentiation in sedum section gormania (crassulaceae)

Analysis of the chromosomal status of the 12 taxa ofSedum sectionGormania reveals a euploid series ofn = 15, 30, and 45. Although plants of all taxa are self-compatible in varying degrees, those of the narrow endemics exhibit a high level of self-compatibility while the plants of all but one of the more widely distributed taxa tend to be weakly self-compatible or rarely selfincompatible. The narrow endemics include four diploids, all putative relicts, and two tetraploids. The widely distributed taxa include four diploids, one tetraploid, and one hexaploid. The differences in ploidal level and the degree of self-compatibility are assessed with respect to their possible roles in the evolutionary history of sectionGormania.     

Pollen morphology of the genus Salvia L. (Lamiaceae) in Turkey

Pollen grains of 30 taxa of the genus Salvia, belonging to sections Salvia, Horminum, Drymosphace, Plethiosphace and Hemisphace from Turkey were examined by light (LM) and scanning electron microscopy (SEM). Detailed pollen morphological characteristics are provided for these taxa. Among the studied taxa, S. verticillata subsp. verticillata from sect. Hemisphace has the smallest pollen grains, and S. pachystachys from sect. Salvia possesses the largest ones. The basic shape of the pollen grains in most taxa is suboblate, oblate-spheroidal or prolate-spheroidal. However subprolate pollen grains are recorded for S. macrochlamys from sect. Salvia. The grains are hexacolpate in all taxa, but in S. recognita from sect. Salvia also octacolpate pollen was found. Three distinct exine sculpturing types exist, reticulate-perforate (the common type), reticulate-granulate and bireticulate. The reticulate-perforate and bireticulate sculpturing patterns can be divided into subtypes based on the number of perforations and the number of secondary lumina in each primary lumen. Pollen morphological characteristics of the taxa studied are compared and discussed on the basis of taxonomical concepts. In some cases, these characters are useful in distinguishing the sections. For instance, the presence of 1-2 large central secondary lumina per primary lumen is a significant character of sect. Horminum separating it from the other sections. As well, the presence of holes on colpus membrane ornamentation can be used as a diagnostic taxonomic character for sectional division between sect. Hemisphace and others. S. ballsiana from sect. Salvia is clearly distinct from the other taxa examined by its unique pollen morphology. Further, for several macromorphologically similar taxa pollen structures provide additional evidence to delimite them from each other.     

Phylogenetic relationships among Japanese flowering cherries (Prunus subgenus Cerasus) based on nucleotide sequences of chloroplast DNA

Flowering cherries are classified into Prunus subgenus Cerasus (family Rosaceae). Nine species and some varieties originated in Japan were used in this study. Phylogenetic relationships among Japanese taxa were analyzed by four chloroplast regions using 46 individuals from 16 taxa. Eighteen haplotypes were distinguished. P. pendula f. ascendens and P. cerasoides formed a clade which is distantly related to other Japanese taxa. These two species were morphologically different from other taxa. All Japanese taxa except for P. pendula f. ascendens formed another clade. All taxa in this clade except for P. maximowiczii showed very similar sequences. However, these taxa could be identified by many morphological characters. Even now, based on previous work, it is thought that interspecific hybridization frequently occurs in flowering cherries. We conclude from the current study, Japanese flowering cherries have experienced complicated speciation arising from hybridization.     

SEM analysis of leaf epicuticular waxes of Sedum section Gormania (Crassulaceae)

Epicuticular leaf waxes in the 12 taxa classified inSedum, sect.Gormania show variation in size, shape, and frequency. All of the taxa exhibit wax platelets, but the platelets in the three putative relicts (S. albomarginatum, S. moranii, S. oblanceolatum) are larger than those in related taxa, and those inS. paradisum are poorly developed. Interspecific hybrids tend to show wax patterns intermediate between those of their respective parents. Hypothetical hybrid origins for the four polyploid taxa in the section have been supported previously by morphological and reproductive data and are further clarified by leaf wax data.     

Checklist of fauna found in zooplankton samples from the Barents Sea

We present a list of zooplankton taxa occurring in the Barents Sea based on our analysis of 360 samples from the upper 100 m of the water column as well as on reports from published sources. Moreover, we provide information on adult size, ecological and geographical distribution, habitat preference and frequency of occurrence of each taxon. The list encompasses a total of 374 species and higher taxa. Most are mesozooplankton, with Copepoda prevailing (153 species), and belong to the holoplankton. However, pseudoplankton, organisms only circumstantially occurring in the water column, also comprise a significant part of the fauna (86 taxa). The coastal zooplankton (264 neritic species) was richer than the fauna of the open sea. In our samples, the majority of the zooplankton taxa were rarely found (94 of 157 taxa, equivalent of 60%), 46 taxa (29%) were moderate and only 17 taxa (11%) were common (found in >80% of the samples). Among these, the copepods Calanus finmarchicus, C. glacialis, Oithona similis and Pseudocalanus minutus were most frequent.     

Plant diversity of Hyrcanian relict forests: An annotated checklist,chorology and threat categories of endemic and near endemic vascular plant speciesOA

In this paper a critical annotated checklist of 256 endemic and near endemic species belonging to 152 genera and 50 families of flowering plants known from Hyrcanian relict forests is presented. Distribution maps of taxa, elevational range, number of known records, chorotypes, life forms, IUCN threat categories and habitat types are also provided. The chorotypes are categorized into eight main patterns: 1) the Omni-Hyrcanian pattern(OH), 2) West Hyrcanian pattern(WH), 3) Manjil-Rudbar pattern(MR...     

Cell Size Distributions of Soil Bacterial and Archaeal Taxa

Cell size is a key ecological trait of soil microorganisms that determines a wide range of life history attributes, including the efficiency of nutrient acquisition. However, because of the methodological issues associated with determining cell sizes in situ, we have a limited understanding of how cell abundances vary across cell size fractions and whether certain microbial taxa have consistently smaller cells than other taxa. In this study, we extracted cells from three distinct soils and fractionated them into seven size ranges (5 μm to 0.2 μm) by filtration. Cell abundances in each size fraction were determined by direct microscopy, with the taxonomic composition of each size fraction determined by high-throughput sequencing of the 16S rRNA gene. Most of the cells were smaller than cells typically grown in culture, with 59 to 67% of cells <1.2 μm in diameter. Furthermore, each size fraction harbored distinct bacterial and archaeal communities in each of the three soils, and many of the taxa exhibited distinct size distribution patterns, with the smaller size fractions having higher relative abundances of taxa that are rare or poorly characterized (including Acidobacteria, Gemmatimonadetes, Crenarchaeota, Verrucomicrobia, and Elusimicrobia). In general, there was a direct relationship between average cell size and culturability, with those soil taxa that are poorly represented in culture collections tending to be smaller. Size fractionation not only provides important insight into the life history strategies of soil microbial taxa but also is a useful tool to enable more focused investigations into those taxa that remain poorly characterized.     

Incomplete Lineage Sorting Is Common in Extant Gibbon Genera

We sequenced reduced representation libraries by means of Illumina technology to generate over 1.5 Mb of orthologous sequence from a representative of each of the four extant gibbon genera (Nomascus, Hylobates, Symphalangus, and Hoolock). We used these data to assess the evolutionary relationships between the genera by evaluating the likelihoods of all possible bifurcating trees involving the four taxa. Our analyses provide weak support for a tree with Nomascus and Hylobates as sister taxa and with Hoolock and Symphalangus as sister taxa, though bootstrap resampling suggests that other phylogenetic scenarios are also possible. This uncertainty is due to short internal branch lengths and extensive incomplete lineage sorting across taxa. The true phylogenetic relationships among gibbon genera will likely require a more extensive whole-genome sequence analysis.     

Higher Thermal Acclimation Potential of Respiration but Not Photosynthesis in Two Alpine Picea Taxa in Contrast to Two Lowland Congeners

The members of the genus Picea form a dominant component in many alpine and boreal forests which are the major sink for atmospheric CO₂. However, little is known about the growth response and acclimation of CO₂ exchange characteristics to high temperature stress in Picea taxa from different altitudes. Gas exchange parameters and growth characteristics were recorded from four year old seedlings of two alpine (Picea likiangensis vars. rubescens and linzhiensis) and two lowland (P. koraiensis and P. meyeri) taxa. Seedlings were grown at moderate (25°C/15°C) and high (35°C/25°C) day/night temperatures, for four months. The approximated biomass increment (ΔD²H) for all taxa decreased under high temperature stress, associated with decreased photosynthesis and increased respiration. However, the two alpine taxa exhibited lower photosynthetic acclimation and higher respiratory acclimation than either lowland taxon. Moreover, higher leaf dry mass per unit area (LMA) and leaf nitrogen content per unit area (N_area), and a smaller change in the nitrogen use efficiency of photosynthesis (PNUE) for lowland taxa indicated that these maintained higher homeostasis of photosynthesis than alpine taxa. The higher respiration rates produced more energy for repair and maintenance biomass, especially for higher photosynthetic activity for lowland taxa, which causes lower respiratory acclimation. Thus, the changes of ΔD²H for alpine spruces were larger than that for lowland spruces. These results indicate that long term heat stress negatively impact on the growth of Picea seedlings, and alpine taxa are more affected than low altitude ones by high temperature stress. Hence the altitude ranges of Picea taxa should be taken into account when predicting changes to carbon fluxes in warmer conditions.     

Chemotaxonomy of some Paleozoic vascular plants. Part II: Chemical characterization of major plant groups

Chemical data are given forCooksonia, Rhynia, Zosterophyllum, Pseudosporochnus, Gosslingia,Crenaticaulis, Leclercqia, Tetraxylopteris, Oocampsa, andArchaeopteris, thus extending principal component analysis of multi-state and discrete characters to 27 Paleozoic plant taxa. Ordination patterns of these data suggest that while overlapping of major plant groups occurs, rhyniophytes, zosterophyllophytes, trimerophytes and other supra-generic taxa may be chemically characterized. The effects of heat (thermolysis) on organic constituents is shown to severely alter chemical profiles of plant taxa and is discussed as a thermometric tool. Taxonomic distancemeasures between plant groupings are suggested to be the result of both preand post-fossilization phenomena.     

Evidence of taxon cycles in an Indo-Pacific passerine bird radiation (Aves: Pachycephala)

Many insular taxa possess extraordinary abilities to disperse but may differ in their abilities to diversify and compete. While some taxa are widespread across archipelagos, others have disjunct (relictual) populations. These types of taxa, exemplified in the literature by selections of unrelated taxa, have been interpreted as representing a continuum of expansions and contractions (i.e. taxon cycles). Here, we use molecular data of 35 out of 40 species of the avian genus Pachycephala (including 54 out of 66 taxa in Pachycephala pectoralis (sensu lato), to assess the spatio-temporal evolution of the group. We also include data on species distributions, morphology, habitat and elevational ranges to test a number of predictions associated with the taxon-cycle hypothesis. We demonstrate that relictual species persist on the largest and highest islands across the Indo-Pacific, whereas recent archipelago expansions resulted in colonization of all islands in a region. For co-occurring island taxa, the earliest colonists generally inhabit the interior and highest parts of an island, with little spatial overlap with later colonists. Collectively, our data support the idea that taxa continuously pass through phases of expansions and contractions (i.e. taxon cycles).     

PRACTICE AND PREJUDICE IN LICHEN CLASSIFICATION

Organismal species exist as historical entities, and essentialistic thinking about ‘ defining ’ species and higher taxa should be avoided. Lichens are biological phenomena that are best understood as processes, and they behave very differently from the model organisms of most systematic theories. Classification and phylo-genetic reconstructions are seen as different endeavours, having different aims and languages. A hierarchical classification is supported, and recognition of super-specific taxa is seen as a matter of convenience. Superspecific taxa may be recognized as groups having correlated features, whereas the common recognition of such taxa bya prioricardinal characters should be abandoned. Superspecific taxa having correlated features are distinctive and are likely to be monophyletic. Distinctive and phylogenetically coherent grades may need naming to avoid nomenclatural instability. In classifications, the hypothesized monophyletic status of taxa may be indicated by some convention. Phylogenetic reconstruction by cladistic parsimony analyses includes assumptions that need scrutinizing and modifying to improve the methodology. Analyses should be examined with respect to robustness for changes in the frequently applied equal weighting assumption. For some types of data ana prioriweight assignment might be possible, or equal weighting may be justified.     

Investigation of hybridization between Asclepias speciosa and A. syriaca using alkanes,fatty acids and triterpenoids

Individuals of Asclepias speciosa and A. syriaca from Kansas and Nebraska were sampled and their alkanes, fatty acids and triterpenoids analyzed. Analysis of variance for 30 compounds yielded four significant and seven highly significantly quantitative differences between the taxa. No qualitative differences were found. Analyses of the components using Well's hybrid distance diagram and principal coordinate analysis confirmed that hybridization as well as introgression is occurring between these taxa in this region. Data from isozymes revealed that the two taxa are almost identical. These data, taken together, are indicative of a closer (perhaps conspecific) relationship between these taxa than previously suggested.     

Chromosome numbers of someOenothera species (subgenusOenothera) from Czechoslovakia

Karyologícal analysis ofOenothera species and stabilized hybrids from Czechoslovakía confirms chromosome number 2n=14 for all 21 taxa investigated. The cytological data of 3 specific and 5 intraspecífic taxa are publíshed for the first time. Chromosome configurations during microsporogenesís are determined in 5 taxa.