Belowground annual ring growth coordinates with aboveground phenology and timing of carbon storage in two tallgrass prairie forb species.

PREMISE OF THE STUDY: Herb chronology, the study of belowground annual growth rings in perennial forbs, has much potential as a tool for monitoring plant growth as a function of environment. To harness this potential, understanding of the coordination between ring ontogeny, aboveground phenology, and the temporal allocation of carbon products belowground in herbaceous forbs must be improved. METHODS: We investigated these relationships in two southern United States tallgrass prairie perennial forb species, Asclepias viridis and Lespedeza stuevei, making monthly excavations for a year. KEY RESULTS: Belowground xylogenesis began when starch reserves were at their seasonal low in the spring as shoots reached maximum height. The highest relative radial growth of the ring occurred concurrently with replenishment of root starch reserves in early summer. Xylogenesis concluded with leaf senescence in late summer and belowground starch reserves near saturation. CONCLUSIONS: By demonstrating that ring ontogeny is tied to early summer starch replenishment, our results illustrate the mechanisms behind previous findings where ring width was highly correlated with summer climatic conditions for these two species. This study provides a new physiological link between how ring chronologies in herbs often accord with growing-season environment; further dissecting this phenomenon is vital in unlocking the potential of herb chronology.

Genomic characterization of Ambrosia asymptomatic virus 1 and evidence of other Tymovirales members in the Oklahoma tallgrass prairie revealed by sequence analysis.

The Plant Virus Biodiversity and Ecology project was undertaken to better understand the nature of plant-viral interactions and the occurrence of non-pathogenic viruses. Plants from the Tallgrass Prairie Preserve (TPP), Osage County, Oklahoma, were surveyed from 2005 to 2008 for the presence of viruses, resulting in the detection, using a virus-like particle enrichment method, of the genome a novel virus, Ambrosia asymptomatic virus 1 (AAV1), from Ambrosia psilostachya DC (western ragweed). Here, we present the genomic organization and genetic variability of AAV1. The virus has a single-stranded RNA genome of about 7408 nt, which has six open reading frames (ORFs). Phylogenetic analysis of the replicase and coat protein ORFs of the virus indicates strongly that the virus should be placed in the genus Mandarivirus. No evidence of recombination was detected. We also report the detection in the TPP of two known viruses and seven other putative viruses, members of the order Tymovirales.

Can settlement in natal-like habitat explain maladaptive habitat selection?

The study of habitat selection has long been influenced by the ideal free model, which maintains that young adults settle in habitat according to its inherent quality and the density of conspecifics within it. The model has gained support in recent years from the finding that conspecifics produce cues inadvertently that help prebreeders locate good habitat. Yet abundant evidence shows that animals often fail to occupy habitats that ecologists have identified as those of highest quality, leading to the conclusion that young animals settle on breeding spaces by means not widely understood. Here, we report that a phenomenon virtually unknown in nature, natal habitat preference induction (NHPI), is a strong predictor of territory settlement in both male and female common loons (Gavia immer). NHPI causes young animals to settle on natal-like breeding spaces, but not necessarily those that maximize reproductive success. If widespread, NHPI might explain apparently maladaptive habitat settlement.

Community terminal restriction fragment length polymorphisms reveal insights into the diversity and dynamics of leaf endophytic bacteria.

BACKGROUND: Plant endophytic bacteria play an important role benefiting plant growth or being pathogenic to plants or organisms that consume those plants. Multiple species of bacteria have been found co-inhabiting plants, both cultivated and wild, with viruses and fungi. For these reasons, a general understanding of plant endophytic microbial communities and their diversity is necessary. A key issue is how the distributions of these bacteria vary with location, with plant species, with individual plants and with plant growing season. RESULTS: Five common plant species were collected monthly for four months in the summer of 2010, with replicates from four different sampling sites in the Tallgrass Prairie Preserve in Osage County, Oklahoma, USA. Metagenomic DNA was extracted from ground, washed plant leaf samples, and fragments of the bacterial 16S rDNA genes were amplified for analysis of terminal restriction fragment length polymorphism (T-RFLP). We performed mono-digestion T-RFLP with restriction endonuclease DdeI, to reveal the structures of leaf endophytic bacterial communities, to identify the differences between plant-associated bacterial communities in different plant species or environments, and to explore factors affecting the bacterial distribution. We tested the impacts of three major factors on the leaf endophytic bacterial communities, including host plant species, sampling dates and sampling locations. CONCLUSIONS: Results indicated that all of the three factors were significantly related (α = 0.05) to the distribution of leaf endophytic bacteria, with host species being the most important, followed by sampling dates and sampling locations.

Metriocnemus erythranthei sp. nov. and Limnophyes viribus sp. nov. (Diptera: Chironomidae: Orthocladiinae): leafminers of monkeyflowers, speedwells, and other herbaceous plants, with new observations on the ecology and habitats of other leaf-mining Chironomidae.

In this study, we describe Metriocnemus erythranthei sp. nov. and Limnophyes viribus sp. nov., leafminers of herbaceous wetland plants. The M. erythranthei larva is a true miner entering fresh leaves and excavating the tunnels, and the L. viribus larva inhabits vacated mines of M. erythranthei. M. erythranthei is widespread in North America, with collections from the Pacific coast to Pennsylvania, and L. viribus has been collected from Iowa and Oregon. We also describe the larva of a possible new species associated with these plants, which we refer to as Metriocnemus sp. "Oregon". A key to the known larval stages of North American Metriocnemus is also provided. Along with providing a detailed account of the mining ecology of these new species, we discuss additional observations of mostly Orthocladiinae midges associated with aquatic and terrestrial plants. These include documenting the rearing of Metriocnemus eurynotus (Holmgren, 1883) from larvae feeding on Impatiens (Balsaminaceae) cotyledons, initially as leafminers and later externally. Larvae of M. eurynotus also were found feeding within mines of M. erythranthei on Veronica (Plantaginaceae) and were collected along with M. erythranthei larvae on leaves of Petasites (Asteraceae).

Co-divergence and host-switching in the evolution of tobamoviruses.

The proposed phylogenetic structure of the genus Tobamovirus supports the idea that these viruses have codiverged with their hosts since radiation of the hosts from a common ancestor. The determinations of genome sequence for two strains of Passion fruit mosaic virus (PafMV), a tobamovirus from plants of the family Passifloraceae (order Malpighiales) from which only one other tobamovirus (Maracuja mosaic virus; MarMV) has been characterized, combined with the development of Bayesian analysis methods for phylogenetic inference, provided an opportunity to reassess the co-divergence hypothesis. The sequence of one PafMV strain, PfaMV-TGP, was discovered during a survey of plants of the Tallgrass Prairie Preserve for their virus content. Its nucleotides are only 73 % identical to those of MarMV. A conserved ORF not found in other tobamovirus genomes, and encoding a cysteine-rich protein, was found in MarMV and both PafMV strains. Phylogenetic tree construction, using an alignment of the nucleotide sequences of PafMV-TGP and other tobamoviruses resulted in a major clade containing isolates exclusively from rosid plants. Asterid-derived viruses were exclusively found in a second major clade that also contained an orchid-derived tobamovirus and tobamoviruses infecting plants of the order Brassicales. With a few exceptions, calibrating the virus tree with dates of host divergence at two points resulted in predictions of divergence times of family specific tobamovirus clades that were consistent with the times of divergence of the host plant orders.

Molecular characterization, ecology, and epidemiology of a novel Tymovirus in Asclepias viridis from Oklahoma.

Native virus-plant interactions require more understanding and their study will provide a basis from which to identify potential sources of emerging destructive viruses in crops. A novel tymovirus sequence was detected in Asclepias viridis (green milkweed), a perennial growing in a natural setting in the Tallgrass Prairie Preserve (TGPP) of Oklahoma. It was abundant within and frequent among A. viridis plants and, to varying extents, within other dicotyledonous and one grass (Panicum virgatum) species obtained from the TGPP. Extracts from A. viridis containing the sequence were infectious to a limited number of species. The virus genome was cloned and determined to be closely related to Kennedya yellow mosaic virus. The persistence of the virus within the Oklahoma A. viridis population was monitored for five successive years. Virus was present in a high percentage of plants within representative areas of the TGPP in all years and was spreading to additional plants. Virus was present in regions adjacent to the TGPP but not in plants sampled from central and south-central Oklahoma. Virus was present in the underground caudex of the plant during the winter, suggesting overwintering in this tissue. The RNA sequence encoding the virus coat protein varied considerably between individual plants (≈3%), likely due to drift rather than selection. An infectious clone was constructed and the virus was named Asclepias asymptomatic virus (AsAV) due to the absence of obvious symptoms on A. viridis.

An innovative faith-based healthy eating program: from class assignment to real-world application of PRECEDE/PROCEED.

The Fostering African American Improvement in Total Health! (FAITH!) Nutrition Education Program is a theory-based, multicomponent health intervention developed and operated in partnership with an East Baltimore church. The program aims to improve eating habits, as well as knowledge and beliefs about healthy eating, among African American adults in order to prevent diseases related to dietary choices. This article addresses the development, design, and formative research that informed the FAITH! program. The main program components are also discussed. Program design used a framework for strategic intervention planning (PRECEDE-PROCEED), and health education theories informed the evaluation process. Formative research was conducted to incorporate the needs and assets of the priority population. The main program components are culturally tailored educational materials, lectures and discussions on diet and related diseases, video presentations on healthy eating, healthy cooking demonstrations/food samples, evaluation, and a church-run healthy food pantry.

Thirteen new species of Agromyzidae (Diptera) from the United States, with new host and distribution records for 32 additional species.

We present novel rearing records of Agromyzidae (Diptera) from throughout the United States. We describe leaf mines or other larval habits for 27 species, plus five others whose identification is tentative, and another five that are identified only to genus due to the absence of male specimens. We review host and distribution data for the known species, reporting 26 new host species records (including the first rearing records for Phytomyza flexuosa Spencer, P. notopleuralis Spencer, and (tentatively identified) Ophiomyia frosti Spencer) and 25 new state records (including the first USA records for P. krygeri Hering, P. thermarum (Griffiths), and (tentatively identified) Liriomyza cracentis Lonsdale). We also describe and provide natural history information for the following 13 new species: Haplopeodes loprestii Eiseman Lonsdale, Liriomyza euphorbivora Eiseman Lonsdale, L. hypopolymnia Eiseman Lonsdale, Melanagromyza arnoglossi Eiseman Lonsdale, M. gentianivora Eiseman Lonsdale, M. hieracii Eiseman Lonsdale, M. rudbeckiae Eiseman Lonsdale, M. urticae Eiseman Lonsdale, M. verbenivora Eiseman Lonsdale, Ophiomyia nabali Eiseman Lonsdale, O. rugula Eiseman Lonsdale, Phytomyza flavilonicera Eiseman Lonsdale, and P. triostevena Eiseman Lonsdale.

Environmental determinants of and impact on childhood asthma by the bacterial community in household dust.

Asthma increased dramatically in the last decades of the 20th century and is representative of chronic diseases that have been linked to altered microbial exposure and immune responses. Here we evaluate the effects of environmental exposures typically associated with asthma protection or risk on the microbial community structure of household dust (dogs, cats, and day care). PCR-denaturing gradient gel analysis (PCR-DGGE) demonstrated that the bacterial community structure in house dust is significantly impacted by the presence of dogs or cats in the home (P = 0.0190 and 0.0029, respectively) and by whether or not children attend day care (P = 0.0037). In addition, significant differences in the dust bacterial community were associated with asthma outcomes in young children, including wheezing (P = 0.0103) and specific IgE (P = 0.0184). Our findings suggest that specific bacterial populations within the community are associated with either risk or protection from asthma.

Pegomya disticha Griffiths and P. cedrica Huckett (Diptera: Anthomyiidae)-first documented case of insects trespassing the silica barrier of Common scouring-rush, Equisetum hyemale L.

Scouring-rushes (Equisetum sg. Hippochaete) are a group of horsetails with perennial aerial shoots strongly encrusted in silica. Accordingly, they seem to resist attacks from most herbivorous insects. Michelsen (2008) speculated that larval development of the European Pegomya terminalis (Rondani) and related anthomyiids takes place in specific scouring-rushes. Presently, we document that the larvae of two North American species related to P. terminalis attack developing shoots of Common scouring-rush, Equisetum hyemale L. Both species, Pegomya disticha Griffiths and P. cedrica Huckett, were found to coexist in a population of scouring-rush in Oklahoma. Various aspects of the life-history and morphology (3rd instar larva, male and female adults) for both species are described and documented by photos.

Non-cultivated plants of the Tallgrass Prairie Preserve of northeastern Oklahoma frequently contain virus-like sequences in particulate fractions.

The diversity of viruses associated with non-cultivated plants was assessed from plant samples collected in the Tallgrass Prairie Preserve of northeastern Oklahoma, USA. The samples were processed to determine the sequences of nucleic acids extracted from the virus-like particle fraction of plant homogenates. Sequences from 95 specimens of 52 plant species included those of probable origin from the genomes of plants (including retroelements), bacteria, fungi, other organisms, and viruses. Virus-like sequences were identified in sequences from 25% of the specimens, coming from 19% of the plant species. Evidence of a member of the genus Tymovirus was found in 16 specimens of 6 plant species, making it the most predominant virus associated with the sampled plants. There was evidence of the presence of more than one virus in each of six specimens.

Modeling the sampling effect in the species-time-area relationship.

Recent empirical work in numerous systems has demonstrated the interdependence of spatial and temporal accumulation of species in the species-time-area relationship (STAR). The purpose of this study was to develop a process-based stochastic model for the STAR that assumes species neutrality and to compare the model's expectations to data collected on plant species in a tallgrass prairie. We varied two important aspects of the neutral species assemblage: evenness in the species pool and individual replacement rate (R). When R is larger than approximately 0.5 and evenness is intermediate to high, the neutral STAR generates patterns qualitatively similar to the empirical STAR. Our model also indicates that space and time were not symmetrical in their effects on species accumulation, except in the special case of R = 1.0. We observed both positive and negative time-by-area interactions in the sampling model, which indicates that nonzero interactions are not necessarily evidence of ecological processes. Furthermore, as accumulated richness approaches the size of the species pool, the time-by-area interaction becomes increasingly negative in our model. This suggests that negative time-by-area interactions should be expected a priori in empirical systems if rates of species accumulation decrease due to increasing rarity of unique species. Given the wide range of STARs that the sampling model generated, the difficulty in estimating key parameters, and the complexity of assessing the relative abundance distribution and scale of the species pool, we cannot refute the sampling effect, and we suggest caution in accepting ecologically oriented explanations of empirical STARs.

Optimization of Plant Growth-Promoting Bacteria-Assisted Phytostabilization of Mine Tailings.

Recent studies have indicated that plant growth-promoting bacteria (PGPB) can improve revegetation of arid mine tailings as measured by increased biomass production. The goals of the present study were first to evaluate how mode of application of known PGPB affects plant growth, and second to evaluate the effect of this inoculation on rhizosphere microbial community structure. PGPB application strategies investigated include preliminary surface sterilization of seeds (a common practice in phytoremediation trials) followed by a comparison of two application methods; immersion and alginate encapsulation. Results with two native desert plant species, Atriplex lentiformis and Buchloe dactyloides, suggest that seed surface sterilization prior to inoculation is not necessary to achieve beneficial effects of introduced PGPB. Both PGPB application techniques generally enhanced plant growth although results were both plant and PGPB specific. These results demonstrate that alginate encapsulation, which allows for long-term storage and easier application to seeds, is an effective way to inoculate PGPB. In addition, the influence of PGPB application on B. dactyloides rhizosphere community structure was evaluated using PCR-DGGE (denaturing gradient gel electrophoresis) analysis of bacterial DNA extracted from rhizosphere samples collected 75 d following planting. A comparative analysis of DGGE profiles was performed using canonical correspondence analysis (CCA). DGGE-CCA showed that rhizosphere community profiles from PGPB-inoculated treatments are significantly different from both uninoculated tailings rhizosphere profiles and profiles from the compost used to amend the tailings. Further, community profiles from B. dactyloides inoculated with the best performing PGPB (Arthro mix) were significantly different from two other PGPB tested. These results suggest that introduced PGPB have the potential to influence the development of the rhizosphere community structure found in plants grown in mine tailings.

Examining the assumptions of heterogeneity-based management for promoting plant diversity in a disturbance-prone ecosystem.

BACKGROUND: Patch-burn management approaches attempt to increase overall landscape biodiversity by creating a mosaic of habitats using a patchy application of fire and grazing. We tested two assumptions of the patch-burn approach, namely that: (1) fire and grazing drive spatial patch differentiation in community structure and (2) species composition of patches change through time in response to disturbance. METHODS: We analyzed species cover data on 100 m2 square quadrats from 128 sites located on a 1 × 1 km UTM grid in the grassland habitats of the Tallgrass Prairie Preserve. A total of 20 of these sites were annually sampled for 12 years. We examined how strongly changes in species richness and species composition correlated with changes in management variables relative to independent spatial and temporal drivers using multiple regression and direct ordination, respectively. RESULTS: Site effects, probably due to edaphic differences, explained the majority of variation in richness and composition. Interannual variation in fire and grazing management was relatively unimportant relative to inherent site and year drivers with respect to both richness and composition; however, the effects of fire and grazing variables were statistically significant and interpretable, and bison management was positively correlated with plant richness. CONCLUSIONS: There was some support for the two assumptions of patch-burn management we examined; however, in situ spatial and temporal environmental heterogeneity played a much larger role than management in shaping both plant richness and composition. Our results suggest that fine-tuning the application of fire and grazing may not be critical for maintaining landscape scale plant diversity in disturbance-prone ecosystems.

Indices for detecting differences in species composition: some simplifications of RDA and CCA.

We provide algebraic simplifications for the redundancy analysis (RDA) eigenvalue and the canonical correspondence analysis (CCA) eigenvalue in the special case of permanent plots sampled twice. The indices for RDA and CCA are interrelated and are intuitively interpretable. These simplifications also apply to simple split-plot designs and to a balanced design with two independent samples.

Evidence for novel viruses by analysis of nucleic acids in virus-like particle fractions from Ambrosia psilostachya.

To test the hypothesis that many viruses remain to be discovered in plants, a procedure was developed to sequence nucleic acids cloned randomly from virus-like particle fractions of plant homogenates. As a test of the efficiency of the procedure we targeted Ambrosia psilostachya, western ragweed, plants growing at the Tallgrass Prairie Preserve of northeastern Oklahoma. Amplifiable nucleic acid was found in the fractions from six of twelve specimens and sequences were characterized from four of them. Evidence was obtained for the presence of viruses belonging to two families (Caulimoviridae, Flexiviridae). Multiple viral species were found in two of the four specimens and their level within the isolated nucleic acid population varied from less than 1-37%. None of the sequences were derived from reported sequences of known viruses. Thus, the analysis of nucleic acid from virus-like particles is a useful tool to expand our knowledge of the universe of viruses to non-cultivated species.

The latitudinal gradient of species-area relationships for vascular plants of North America.

The species-area relationship (SAR), describing the increase in species richness with increasing area, and the latitudinal diversity gradient (LDG), describing the decrease in species richness with increasing latitude, are the oldest and most robust patterns in biogeography, yet connections between them remain poorly understood. Here, using 1,742 floras covering the entirety of North America north of Mexico (NAM) and including all of NAM's native species of vascular plants, we show that the slope of the SAR consistently decreases with increasing latitude. This trend is general and holds for subsets of the floras in eastern and western NAM. The southernmost latitudinal quarter of NAM exhibits SARs more than twice as steep as those of the northernmost quarter for both eastern and western regions. This decrease in SAR slope with increasing latitude is consistent with the environmental texture hypothesis and Rapoport's rule, and it suggests that more detailed studies of species endemism in relation to environmental and historical factors will yield significant insights into the underlying causes of SAR and LDG patterns.

A new species of Marmara (Lepidoptera: Gracillariidae: Marmarinae), with an Annotated List of Known Hostplants for the Genus.

Larvae of the New World gracillariid moth genus Marmara are primarily stem/bark miners, with some species mining in leaves or fruits. We describe a new species, M. viburnella Eiseman & Davis, which feeds on Viburnum, initially mining the leaves but completing development as a stem miner. The type series is from Nantucket Island, Massachusetts, with observations of leaf mines indicating the species is widespread in the eastern USA. Combining previously published data, our own observations, and other sources, we present a list of known Marmara hostplants, many of which represent undescribed species.

Latitudinal trends in genus richness of vascular plants in the Eocene and Oligocene of North America.

The latitudinal richness gradient is a frequent topic of study on the modern landscape, but its history in deep time is much less well known. Here, we preliminarily evaluated the paleolatitudinal richness gradient of vascular plants for the Eocene (56-33.9 million years ago) and Oligocene (33.9-23 million years ago) epochs of North America north of Mexico using 201 fossil floras. We calculated the direction and shape of the gradient using quadratic regression to detect linear and curvilinear trends. We performed regressions for the Eocene and Oligocene as well as for informal time intervals within the Eocene: early, middle, and middle + late. We found that quadratic models better explain the data than linear models for both epochs as well as for the early Eocene. A roughly linear trend in the middle and middle + late intervals may reflect limited sampling of high latitude floras for those times. The curvilinear relationship was weak for the Eocene and the model showed a peak in richness at 45.5°N. The curvilinear relationship was much stronger for the Oligocene and the peak occurred at 48.5°N. In the Eocene, the mid-latitude peak in richness may be explained by mean annual temperature, which was probably higher at some mid-latitudes than at lower ones. For the Oligocene, the peak in richness at mid-latitudes may be explained by evolutionary diversification within the temperate zone or by increased aridity at low latitudes. We also assessed the latitudinal richness gradient of genera within modern floras in North America north of Mexico and we found a weak, curvilinear trend with a peak in richness at 31.5°N. Our results suggest that the latitudinal genus richness gradient of vascular plants in North America continued to develop into its modern structure following the Oligocene.