Department: Environmental and Plant Biology (Arts and Sciences) ![[clear]](close-x.png "Remove this limiter")
18 matches in the database.
These are records: 1 - 18.
Did you mean instcode:ohio?
1.
Briju, Betsy J.
Progress of Work towards Cloning Gravity Persistence Signal (gps) Mutants by PCR-Based Methods and Positional Mapping.
Degree: PhD, Environmental and Plant Biology (Arts and Sciences), 2011, Ohio University
► Gravitropism is a growth response that enables a plant to orient its…
(more)
▼ Gravitropism is a growth response that enables a plant to orient its organs for efficient utilization of natural resources. A change in the gravity vector is sensed by the plant when statoliths sediment towards the new bottom of the cell. As a result, asymmetric distribution of auxin occurs, leading to differential growth. The signaling events that link statolith sedimentation and asymmetric auxin transport are still not well known. Gravity Persistence Signal mutants are a class of T-DNA tagged Arabidopsis mutants potentially defective in the signal transduction events. This research was aimed at identifying the genes altered in these mutants and thereby understanding the function of these genes in the process of gravitropism. PCR based methods such as Thermal Asymmetric Interlaced (TAIL) PCR, inverse PCR and adaptor ligation methods have been used to identify the flanking regions of the T-DNA insertion in gps2 and gps6. Although gps2 is no longer Kanamycin resistant, there is evidence that a part of the tag remains intact. The T-DNA tags in three of these mutants seem to have extended regions integrated beyond the canonical left border. PCR results also indicated a possibility of tandem tags. Southern hybridization results provide further evidence that gps5 and gps6 may have more than one T-DNA tags. The current knowledge on the T-DNA ends in both gps2 and gps6 suggests that a unique T-DNA region among the tandem tags, is present that would prove helpful in using modified PCR-based methods to identify the mutated genes. A F2 mapping population has been generated for map-based cloning of gps2 and gps6. Upon identification of homozygous plants in the F2 segregating population, screening for linked markers can be done from among the chosen 26 markers. If a pair of flanking markers are identified that are located on the same BAC or PAC, candidate genes could be found in their vicinity and therefore analyzed. Alternately, deep sequencing could be adopted to identify the candidate genes in the vicinity of these markers. Identification of GPS2 and GPS6 will help in delineating mechanisms that provide a sense of direction to the graviresponding plant.
Advisors/Committee Members: Wyatt, Sarah.
Subjects: Cellular Biology; Molecular Biology; Plant Biology
Keywords: Gravitropism; T-DNA insertion; Molecular mapping; Gravity persistence signal; Feldmann T-DNA; Bimolecular Fluorescence Complementation
More Like This
2.
Dodson, Thomas M.
Genetic and phenotypic variation in Japanese knotweed (Fallopia japonica) in the Eastern United States.
Degree: MS, Environmental and Plant Biology (Arts and Sciences), 2009, Ohio University
► Molecular markers can be used to find the genetic relatedness of an…
(more)
▼ Molecular markers can be used to find the genetic relatedness of an invasive species and reconstruct certain aspects of the path of invasion. Japanese knotweed, Fallopia japonica (Houtt.) Ronse Decr. (Polygonaceae), was used as a model to test how sexual reproduction and clonal propagation have affected the species‚ invasion history in the eastern United States and what model of spread is likely. Three microsatellite markers and reciprocal transplants were used to assess the genetic variation in three regions of the eastern United States: Michigan, Ohio, and the Southern Appalachians. Knotweed was found to be highly clonal but also reproducing sexually. No path of invasion could be ascertained and the patterns of genetic similarity were such that a hierarchical model of spread (with long-distance dispersal implicated as very important) has mostly likely occurred in the three regions as well on the continental scale.
Advisors/Committee Members: Matlack, Glenn R.
Subjects: Biology; Botany; Ecology
Keywords: microsatellite; Japanese knotweed; Polygonum cuspidatum; Fallopia Japonica; invasive species; genetic diversity; population genetics; biological invasions
More Like This
3.
Homsher, Ryan B.
Growth and Reproduction of Oaks in Southeastern Ohio.
Degree: MS, Environmental and Plant Biology (Arts and Sciences), 2012, Ohio University
► Masting is the synchronous intermittent production of large seed crops by a…
(more)
▼ Masting is the synchronous intermittent production of large seed crops by a population of plants. Two mixed oak forests in southeastern Ohio were selected to examine the abundance and synchrony of acorn crops over a nine-year period. Black oak (Quercus velutina) and chestnut oak (Q. prinus) acorns were collected monthly during the fruiting season. To examine the effects of silvicultural stand treatment, reproduction were examined for both species in stands that had experienced thinning, burning, thinning + burning, and an untreated control. Primary growth (canopy twig extension) and secondary growth (annual increment) was also studied to ascertain if patterns of resource allocation shift between growth and reproduction during a mast event. Anthropogenic disturbances did not have an effect on oak masting synchrony. Chestnut oak acorn production in thin + burn treatments was increased in relation to other treatments during two of the three mast years. No pattern of resource switching was observed between mast events when compared with primary and secondary growth. In the populations of both species, there were individuals that consistently produced acorns every mast year and others that failed to, suggesting strong genetic or microsite control.
Advisors/Committee Members: McCarthy, Brian.
Subjects: Botany; Ecology; Forestry
Keywords: Masting; Disturbance; Resource Allocation; Radial Growth; Primary Growth
More Like This
4.
Hougen, Krysta E.
Long-term Effects of Industrial History on the Forest Flora of Southeastern Ohio.
Degree: MS, Environmental and Plant Biology (Arts and Sciences), 2009, Ohio University
► Throughout the Appalachians, residual effects from furnace and mining industries may still…
(more)
▼ Throughout the Appalachians, residual effects from furnace and mining industries may still influence plant communities. The purpose of this project is to determine if the species composition on two industrial sites in Ohio differs from reference forests. The long time since industrial abandonment (120 years) provides insight into the potential for forests to regenerate to their natural plant composition. Plots were established on remnant industrial disturbances and in reference forests as controls. Plots were described based on species composition, soil properties, and community characteristics. Results indicate differences between industrial and reference forest sites, and the microsites within the industrial sites (i.e., waste dumps). Differences can be attributed to soil pH and cation concentrations, as well as disturbance intensity and frequency. This study argues that the plant community is still affected by century old industrial activities. Identifying the most influential disturbances could aid in restoring industrial sites.
Advisors/Committee Members: Matlack, Glenn R.
Subjects: Biology; Botany; Ecology
Keywords: Ohio Industrial history; Charcoal-iron furnace; revegetation; industrial disturbance
More Like This
5.
Johnston, Emily T.
The Systematic Revision of the Freshwater Red Algal Order Thoreales (Nemaliophycidae, Rhodophyta).
Degree: MS, Environmental and Plant Biology (Arts and Sciences), 2012, Ohio University
► The freshwater red algal order Thoreales has a worldwide distribution and contains…
(more)
▼ The freshwater red algal order Thoreales has a worldwide distribution and contains two genera, Nemalionopsis with two species, and Thorea with four to 11 species recognized by various researchers. The controversy surrounding the number of Thorea species stems from a lack of discrete morphological characters to define taxa and little molecular data generated to date to inform phylogenetic studies. Previous research focused on morphology, placed most taxa in synonymy with either T. violacea or T. hispida, but also recognized T. zollingeri and T. clavata as distinct, leaving four morphological species in Thorea. Within Nemalionopsis, N. shawii was recognized, but N. shawii forma caroliniana was synonymized with N. tortuosa. A recent molecular study hinted at greater genetic diversity within the Thoreales than shown by the morphologically circumscribed taxa. The goal of this research was to determine the number of phylogenetic species within the order and assess biogeographic trends. Specimens were collected in Europe, temperate and sub-tropical North America, the Caribbean, South America, Eastern Asia and South Pacific Islands. Sequence data for 40 specimens were generated for the rbcL (chloroplast) gene, the LSU (nuclear) gene, and the COI barcode (mitochondrial). Bayesian Inference and Maximum Likelihood analyses indicated a much greater number of species within the Thoreales than currently recognized from morphological analyses. This research has uncovered four species within Nemalionopsis and ten in Thorea; however, more diversity is suspected as both genera are probably under-collected worldwide. The taxon, T. hispida, is a cosmopolitan species with little genetic variation among specimens from four continents. All other taxa within the Thoreales appear to have restricted geographic ranges.
Advisors/Committee Members: Vis, Morgan.
Subjects: Biology; Botany
Keywords: Thoreales; Thorea; Nemalionopsis; Systematics; Freshwater Red Algae; Rhodophyta; Thoreaceae
More Like This
6.
Larson, Jason S.
The Vascular Flora of Salt Fork State Park, Guernsey County, Ohio.
Degree: MS, Environmental and Plant Biology (Arts and Sciences), 2011, Ohio University
► Salt Fork State Park is the largest Ohio state park, encompassing 8167…
(more)
▼ Salt Fork State Park is the largest Ohio state park, encompassing 8167 hectares and accounting for nearly 10% of all state park land. While the majority of state park land is utilized for public recreation, many parts of these parks are isolated and seldom used by the public. These remote areas potentially provide habitat and protection for endangered and threatened species. However, there is limited information available about the flora and fauna of most Ohio state parks. The purpose of this study was to document thoroughly the vascular plant diversity in Salt Fork State Park. To reduce the likelihood of overlooking species that are rare, inconspicuous or difficult to identify, a list of species that are likely to occur in the park and their preferred habitats was compiled based on the previously documented flora of Guernsey County and surrounding counties. Comprehensive surveys of all habitats in the park were conducted throughout the 2008 and 2009 growing seasons, building on preliminary work (1997 – 2007) carried out before this M.S. research was initiated. From 1997 to 2009, 117 families, 390 genera, and 719 species of vascular plants were identified within park boundaries. Of the 719 species, 142 comprise new records for Guernsey County. Among them were populations of the state endangered Carex bushii and Viola tripartita var. glaberrima. In addition, a non-native species, Kyllinga gracillima, was found for the first time in Ohio. Voucher specimens for all species found in 2008 and 2009 have been deposited in the Ohio University Floyd Bartley Herbarium. This study is intended to provide a model for those who seek to document the floristic diversity of other state parks and evaluate habitats for conservation management and habitat restoration.
Advisors/Committee Members: Cantino, Phil.
Subjects: Botany
Keywords: Salt Fork State Park; Guernsey County, Ohio; Vascular Flora; Floristic Survey
More Like This
7.
McCarthy, Dawn R.
Belowground Carbon Processes in Managed Oak-Hickory Forests of Southeastern Ohio.
Degree: PhD, Environmental and Plant Biology (Arts and Sciences), 2008, Ohio University
► Soil CO2 efflux (soil respiration) is the largest flux of carbon from…
(more)
▼ Soil CO2 efflux (soil respiration) is the largest flux of carbon from terrestrial forest ecosystems. Understanding this flux in relation to forest thinning and prescribed burning is necessary for determining the effects of forest management on forest carbon dynamics. Since rising levels of atmospheric carbon dioxide are of global concern, my dissertation focused on providing insight into various aspects of soil respiration as it relates to forest management. Specifically, my research focused on (1) the effects of topographic position, canopy cover, and small-scale treatment on soil respiration (Rs) and soil microclimate; (2) modeling Rs with soil microclimate data and climate data; (3) the effects of large-scale forest thinning and prescribed fire on Rs and soil microclimate; and (4) the relationship between forest management and forest carbon budgets. In studies of topographic position, canopy cover, and small-scale treatments, I discovered that landscape position affected Rs, with greater Rs on upper slopes than lower slopes. Low-intensity prescribed fire affected Rs, whereas high-intensity prescribed fire did not. Modeling of Rs supported the use of soil temperature for predicting Rs, with linear regression of ln (Rs) providing the best fit, as opposed to widely used Arrhenius-type nonlinear models. Additionally, I predicted Rs using air temperature and relative humidity data from the local weather station (R2 = 0.94). Studies of large-scale thinning and burning resulted in reduced Rs up to 3 growing seasons after forest harvesting, followed by elevated Rs in the fourth growing season, and Rs comparable to control the fifth growing season following harvest. Prescribed fire led to greater Rs three growing seasons post-fire, and Rs comparable to control by the fourth growing season. Rs was reduced in burn treatments the growing season following a second prescribed burn in 2005. Air temperature was used to estimate annual soil respiration (Fsoil) for each treatment. Combining Fsoil with annual litter biomass and woody biomass increment, I was able to develop a forest ecosystem carbon budget for each treatment. These component fluxes are only estimates, but they provide the first step towards understanding the partitioning of carbon between ecosystem components within oak-hickory forests in southeastern Ohio.
Advisors/Committee Members: Ballard, Harvey E.
Subjects: Ecology; Forestry; Soil sciences
Keywords: carbon; forest; fire; Ohio; oak; soil respiration; soil CO2 efflux; forest ecology; forest management; thinning; soil ecology; topography
More Like This
8.
Miller, Nathaniel P.
Invasions of Secondary Forest by a Nonnative Grass Species: Microstegium vimineum {Nees}(Poaceae).
Degree: MS, Environmental and Plant Biology (Arts and Sciences), 2011, Ohio University
► Shade-tolerant invasive plant species are threatening deciduous forest communities of the eastern…
(more)
▼ Shade-tolerant invasive plant species are threatening deciduous forest communities of the eastern United States, but their method of invasion remains unclear. We test the idea that arrival of one such species, the non-native annual grass Microstegium vimineum {Nees}(Poaceae), is facilitated by movement of humans or animals by direct observation of distributions along movement corridors over two years. Weak colonization of experimental plots shows that Microstegium is limited by seed availability, and to a lesser extent litter cover, in the absence of human or animal movement. Inconsistent extension of populations along off-road-vehicle trails, small roads, and stream sides did not indicate increased movement of seeds by vehicles, road equipment, and water in my field sites. Saturation of isolated roadside sites demonstrates that within-site colonization is very rapid relative to colonization between sites. Little extension along footpaths and horse trails implies that pedestrian and horse movements are not important mechanisms of invasion. Dispersal experiments indicate that adhesion may be a feasible dispersion technique for Microstegium vimineum, and may dictate the spatial patterns of colonization. These results suggest that Microstegium invasions are spatially hierarchical, with different mechanisms acting on different scales, and that invasion may take place in series of explosions of growth and periods of little or no growth. Management focused on controlling dispersal and focusing efforts on the local scale will be most effective at controlling the spread of this species.
Advisors/Committee Members: Glenn, Matlack.
Subjects: Ecology
Keywords: invasive species, ecology, invasion
More Like This
9.
Pool, Justin R.
Use of Diatom Assemblages and Biofilm Enzyme Activities for Assessment of Acid Mine Remediated Streams in Southeastern Ohio.
Degree: MS, Environmental and Plant Biology (Arts and Sciences), 2010, Ohio University
► Coal is the primary energy source for the United States and is…
(more)
▼ Coal is the primary energy source for the United States and is obtained through either surface or underground mining. Prior to the 1970s there were few regulations regarding the operation and subsequent reclamation of mines and the operators were not mandated to prevent acidic mine drainage (AMD) from leaching into the local watershed. This AMD is characterized by low pH, sulfate-rich water, and high levels of dissolved metal cations. Two alkaline doser remediation projects, Monday Creek and Hewett Fork, were assessed for effectiveness by sampling the diatom assemblage structure, biofilm extra-cellular enzyme activities, and water chemistry. The diatom assemblages were examined upstream of the remediation site and at 9 locations downstream. Biofilm enzyme activities, water chemistry, and total chlorophyll a were measured at 6 locations on each stream. Based on the diatom community composition, water quality improved greatly in Hewett Fork 16.5 kilometers downstream from the remediation site, while Monday Creek remained impacted over the 41.5 kilometers sampled. The biofilm enzyme activites supported the findings of the diatom community composition in both streams studied. The Monday Creek watershed has multiple sources of AMD downstream of the remediation project, thus the effectiveness appears to be counteracted by these inputs; whereas, Hewett Fork does not have substantial downstream AMD inputs and the remediation project seems to be more effective in restoring the diatom assemblage and stream functioning further downstream.
Advisors/Committee Members: Vis, Morgan L.
Subjects: Biology; Ecology; Mining
Keywords: Acid mine drainage; AMD; diatom index of biointegrity; mining reclamation
More Like This
10.
Redwood, Mame S.
The Effect of Silviculture Management on the Spread of Three Invasive Species.
Degree: MS, Environmental and Plant Biology (Arts and Sciences), 2012, Ohio University
► Disturbance such as forest management is thought to promote invasive species spread.…
(more)
▼ Disturbance such as forest management is thought to promote invasive species spread. This study uses population demography to address the spread of the invasive species Ailanthus altissima, Alliaria petiolata, and Microstegium vimineum in forested sites in southeast Ohio. Invasive species populations were examined in the silvicultural treatments prescribed burn and timber harvest, plus control plots with no management. Seed rain, seedling establishment, and the soil seed bank was studied for each population. All invasive seeds formed a persistent seed bank and experienced seasonal dormancy, but the proportion of dormant seeds varied among species (p<0.05). Slope aspect effected seed survivorship and dormancy (p<0.05) for each species. Dormancy for each species showed no relationship or a weak relationship with time since seed burial. Invasive populations expanded at a constant rate among treatments, and invasive seeds changed dormancy conditions seasonally to allow for germination during favorable conditions, which may contribute to invasive ability.
Advisors/Committee Members: Matlack, Glenn.
Subjects: Botany
Keywords: invasive; harvest; burn; spread; Microstegium vimineum; Ailanthus altissima; Alliaria petiolata; dormancy; germination; slope; aspect; seed; survivorship; ecology; garlic mustard; japanese stiltgrass; tree of heaven; dispersal; establishment
More Like This
11.
Rosenberg, Chase C.
Foliar Chemical Analysis, Decomposition, and Effects on Nutrient Cycling of American Chestnut and its Hybrids.
Degree: MS, Environmental and Plant Biology (Arts and Sciences), 2010, Ohio University
► The American chestnut, Castanea dentata (Marsh.) Borkh, was once the dominant species…
(more)
▼ The American chestnut, Castanea dentata (Marsh.) Borkh, was once the dominant species of many hardwood forests in eastern North America. A fungal pathogen introduced in 1904 killed mature chestnuts range-wide. Recent work has resulted in a putatively pathogen-resistant chestnut hybrid, making future reintroduction a distinct possibility. However, information on the chemistry and potential effects on nutrient cycling of the chestnut hybrid is necessary to understand the consequences of reintroduction. I predicted that litter from chestnut taxa would contain more recalcitrant compounds and subsequently decompose more slowly than the extant species Quercus alba L. and Acer saccharum Marshall. Lignin and tannin are secondary compounds which are known to inhibit decomposition, and which I predict will be relatively abundant in chestnut litter. I also predicted that there are no significant differences between the foliar nutrient content of the hybrid and American chestnut. In this experiment, I measured tannins, litter fractions, ten nutrient elements, and both decomposition rates and enzyme activity (in the Oe/A horizon) of leaves of C. dentata, C. mollissima Blume, hybrid chestnut, Quercus alba , Q.prinus L., Acer rubrum L., and A. saccharum. Nutrient resorption was also quantified in order to further understand hybrid chestnut's potential effect on forest nutrient pools. No significant differences in chemistry or decay rate were found among any of the chestnut taxa. Chestnut contained more tannin than non-chestnut species, and contained slightly more mass after one year of decomposition, but all metrics tested were within the ranges of co-occurring species. These data suggest that a reintroduction of hybrid chestnut will not likely alter nutrient cycles in Appalachian hardwood forests.
Advisors/Committee Members: McCarthy, Brian.
Subjects: Ecology
Keywords: chestnut; castanea dentata; restoration; foliar chemistry; decomposition
More Like This
12.
Salomaki, Eric D.
A Systematic Investigation of Batrachospermum section Helminthoidea (Batrachospermales, Rhodophyta) Using Molecular and Morphological Analyses.
Degree: MS, Environmental and Plant Biology (Arts and Sciences), 2012, Ohio University
► Previous research has provided strong support for Batrachospermum arcuatum, B. boryanum, B.…
(more)
▼ Previous research has provided strong support for Batrachospermum arcuatum, B. boryanum, B. confusum, B. confusum forma anatinum, B. heterocorticum, and B. involutum forming the clade taxonomically known as Batrachospermum section Helminthoidea. All taxa, except B. arcuatum, share the morphological trait of heterocortication, but there are few other morphological characters that have been reliable for distinguishing taxa. Thus, the number of species and their relationships within Batrachospermum section Helminthoidea are unclear and need further research. This study examined molecular data from 96 specimens and morphological characteristics of 64 specimens collected from North America, New Zealand and Europe. Based on these data, there are at least 8 distinct species belonging to Batrachospermum section Helminthoidea. A suite of morphometric characters showed separation among molecular clades; however, there is no single morphological autapomorphy for most species (clade) that distinguished the species from all others. Additionally, section Helminthoidea can be defined by the underlying synapomorphy of heterocortication shared by most species and potentially secondarily lost in a few taxa.
Advisors/Committee Members: Vis, Morgan.
Subjects: Plant Biology
Keywords: Batrachospermum; Rhodphyta; Phylogenetics; Freshwater Red Algae; Molecular Systematics
More Like This
13.
Schenck, Craig A.
Using Quantitative Proteomics to Study the Early Events of Gravitropism.
Degree: MS, Environmental and Plant Biology (Arts and Sciences), 2012, Ohio University
► Gravity is an important environmental stimulus that orients plant growth. A plant’s…
(more)
▼ Gravity is an important environmental stimulus that orients plant growth. A plant’s response to gravity, gravitropism, allows for the plant to efficiently obtain resources. Gravitropism can be simplistically separated into three phases: perception, signal transduction and differential growth. Perception occurs through the sedimentation of dense starch-filled plastids called amyloplasts. This triggers a yet to be determined cascade of events that results in an auxin concentration at the new lower side of the gravistimulated organ. The last step is differential growth (growing against the gravity vector in the inflorescence stems) which is a result of the auxin concentration. There is a vast hole in the knowledge of the signaling events during gravitropism. The objective of this research was to identify proteins that may be involved in the signaling phase of gravitropism and with other data produced from our lab, start to construct a model of gravitropism in the inflorescence stems. A mutant screen was developed, the Gravity Persistent Signal (GPS) treatment that aids in the identification of mutants in the signal transduction phase of gravitropism. The screen utilizes a cold gravistimulation step to temporally separate the perception events from a differential growth response. Multiple genes/mutants involved in signal transduction have been identified by this approach, but only a few of them have been cloned. The main focus of previous research was to screen a mutant population to identify a single gene. This strategy can only get so far and identify a limited amount of components. A proteomics approach provides a top-down approach which will scan the proteome rather than a bottom-up approach that only looks at a single gene. This will allow for the compilation of data from multiple approaches, which may help in constructing a model of gravitropic signaling. To identify proteins that are differentially translated or have undergone post translational modifications (PTMs) the GPS treatment was used. Proteins were extracted at key time points during the GPS treatment and analyzed using a quantitative proteomics approach. Over 1,400 proteins were identified using this approach, 82 of which showed significant differential quantification. Ten of the 82 proteins were analyzed in more depth by characterizing plants with T-DNA insertions in the genes encoding these proteins. Some of these mutants displayed altered gravitropic responses. These results demonstrate that proteins identified through this approach are indeed involved in gravitropism.
Advisors/Committee Members: Wyatt, Sarah.
Subjects: Molecular Biology; Plant Biology
Keywords: gravitropism; signal transduction; proteomics; iTRAQ
More Like This
14.
Schori, Melanie.
A Systematic Revision of Gomphandra (Stemonuraceae).
Degree: PhD, Environmental and Plant Biology (Arts and Sciences), 2010, Ohio University
► The genus Gomphandra Wall. ex Lindl. was studied and revised to more…
(more)
▼ The genus Gomphandra Wall. ex Lindl. was studied and revised to more accurately reflect the diversity of the group. Floral morphology and fruit anatomy were compared to other genera of Stemonuraceae to assess reproductive diversity within the family and identify potential synapomorphies. Seven genera of Stemonuraceae possess what appears to be a unique fruit type: a laterally compressed drupe with fleshy appendage that aids in dispersal. Fruit of nine genera were sectioned, and all exhibit sclerified longitudinal bundles in the inner mesocarp; one bundle, which appears bright in cross-section under polarized light, may be a synapomorphy for the family. Seed coats are vascularized with a chalazal/post-chalazal bundle (7 genera) or a pachychalazal bundle (2 genera). Molecular data were sampled from four gene regions (rbcL, trnL intron, trnL-F spacer, matK) in 10 species of three genera (Gomphandra, Grisollea, Stemonurus), for a total of 24 new sequences. Preliminary evidence suggests Grisollea and Codiocarpus (both with a laterally compressed fruit) are more closely related to each other than to Stemonurus or Gomphandra, which have uncompressed fruits. Members of Stemonuraceae may have a molecular synapomorphy in a 100 base pair region of TA repeats in the trnL-F spacer that is apparently not shared with any genera outside the family. Gomphandra has two moderately supported clades, one with the synapomorphy of terminal (vs. axillary) inflorescences. The revision of the genus recognizes 62 taxa: 56 species, three subspecies, and three varieties. Diversity is highest in the Philippines (17 taxa), followed by Borneo and Papua New Guinea (10 taxa each), and Sumatra (9 taxa). Twenty-nine new taxa are described, three species are resurrected, one species is reduced in status, and five taxa are synonymized. Problems with typification and nomenclature are corrected for 24 species of Gomphandra and six species in four other genera of Stemonuraceae.
Advisors/Committee Members: Cantino, Philip D.
Subjects: Biology; Botany
Keywords: Stemonuraceae; Gomphandra
More Like This
15.
Scott, Lindsay G.
Seasonal and Spatial Influences on Soil Properties, Microbial Composition and Function in a Mixed Mesophytic Forest.
Degree: MS, Environmental and Plant Biology (Arts and Sciences), 2010, Ohio University
► Soil microorganisms play a vital role in the functioning of deciduous forested…
(more)
▼ Soil microorganisms play a vital role in the functioning of deciduous forested ecosystems. Though it is known that these organisms are important mediators of ecosystem functioning (e.g., decomposition), the seasonal and spatial factors that regulate the composition and function of the microbial community are not well understood. In order to determine the seasonal and spatial influences on nutrient availability and soil microbial community dynamics, I set up an observational study in a 42 km2 area in the mixed-mesophytic forest region of southeastern Ohio. Thirty-six plots were set up in six regions and were sampled on three dates in the winter and summer of 2009. I found both season and plot aspect to be major influences on soil fertility as well as the composition and function of the microbial community. Soil acidity and parameters relating with soil pH were found to be the main drivers of microbial composition with the exception of plots with southwest exposure. Results indicate that seasonal and spatial dynamics of soils must be considered in order to fully understand the temperate forested ecosystem.
Advisors/Committee Members: DeForest, Jared.
Subjects: Biogeochemistry; Environmental science; Soil sciences
Keywords: soil; PLFA; season; aspect; microbial community; southeast Ohio
More Like This
16.
Smucker, Nathan J.
Using Diatoms and Biofilms to Assess Agricultural and Coal Mining Impacts on Streams, Spatio-Temporal Variability, and Successional Processes.
Degree: PhD, Environmental and Plant Biology (Arts and Sciences), 2010, Ohio University
► Aquatic organisms are excellent indicators of human impacts on stream ecosystems because…
(more)
▼ Aquatic organisms are excellent indicators of human impacts on stream ecosystems because they provide valuable services and integrate the effects of multiple stressors over time and space, which would be difficult to assess if only considering water chemistry. Agriculture and acid mine drainage (AMD) from historic coal mining contribute to the concentrations of nutrients, conductivity, and pH of streams; all of which are important to the presence and abundance of diatom species. Based on diatom responses to environmental conditions, this research (1) developed indices and examined relationships of metrics with chemistry and land use variables throughout the Western Allegheny Plateau of Ohio and two watersheds, (2) identified how habitat heterogeneity and sampling methods affect diatom diversity patterns and biomonitoring, (3) examined how spatial factors influence diatom assemblage structure and bioassessments, (4) characterized how temporal variability in seven reference and seven non-reference streams affects bioassessments, and (5) documented how AMD impacts biofilm succession, structure, and function as measured by extracellular enzymes. In anthropogenically impacted streams, diatom assemblages showed significant decreased similarity to reference sites, increased % high nutrient diatoms, increased % motile diatoms, and decreased % low nutrient diatoms associated with increased agriculture, and increased % acidophilic diatoms was associated with reduced alkalinity caused by AMD impacts. Intermediate percentages of epilithic habitat promoted diatom diversity, and multiple habitat samples had stronger relationships with watershed impacts than epilithic habitat samples. Spatial factors contributed to diatom assemblage structure likely because of species dispersal within watersheds and the region, but metrics were influenced less by spatial factors. Diatom metrics responded to two-week lags in PO4-P concentrations, and samples collected toward the end of summer were good indicators of mean nutrient concentrations of the entire summer. All streams experienced similar seasonal changes in nutrients and diatom assemblage structure. Reference sites were consistently classified as minimally-impacted streams within a sampling season and among years, which supports their reliability as benchmarks for ecological integrity. AMD reduced diatom diversity, altered carbon dynamics, caused severe P limitation as indicated by a significant increase in phosphatase activity, and reduced algal biomass where aluminum precipitates coated substrata.
Advisors/Committee Members: Vis, Morgan.
Subjects: Biology; Botany; Ecology; Environmental science
Keywords: Biomonitoring; diatoms; Acid mine drainage; agricultural impacts; streams; biofilms; succession; extracellular enzyme activities; water quality; bioassessment; algae; nutrients; spatial and temporal variability; periphyton; habitat heterogeneity
More Like This
17.
Wahlert, Gregory A.
Phylogeny, Biogeography, and a Taxonomic Revision of Rinorea (Violaceae) from Madagascar and the Comoro Islands.
Degree: PhD, Environmental and Plant Biology (Arts and Sciences), 2010, Ohio University
► Rinorea Aublet is a pantropical genus of shrubs and small trees and…
(more)
▼ Rinorea Aublet is a pantropical genus of shrubs and small trees and is the second most species-rich genus in the Violaceae with an estimated 225—275 species. The species in Madagascar and the Comoro Islands have not been revised since 1949, nor has there been an adequate understanding of infrageneric groupings, phylogeny, and biogeography for the entire genus. The goals of this study were: 1) taxonomic revisions of two species-rich infrageneric groups of Malagasy and Comorian Rinorea (R. subsect. Verticillatae and the R. arborea species group), 2) a revised infrageneric classification of the African and Malagasy species, 3) phylogenetic reconstruction inferred from chloroplast DNA sequences with genus-wide taxon sampling, and 4) biogeographic inferences of the Malagasy species. The revision of the genus Rinorea arborea group and R. subsect. Verticillatae, resulted in nine and three new species, respectively. Forty-one species of Rinorea are here recognized for Madagascar and the Comoro Islands. A newly proposed infrageneric classification of African and Malagasy Rinorea—based on morphometric and molecular phylogenetic evidence—recognizes 11 taxonomic sections, including four new sections: Arboreae, Squamosae, Angustifoliae, and Ellipticae. Phylogenetic analyses of three chloroplast regions (trnL-trnF spacer, trnL intron, and trnD-trnE spacer) provided strong branch support for a Paleotropical clade, which was further divided into two subclades: a 3-ovule clade and a 6-ovule clade. Rinorea subsect. Verticillatae showed a moderately to highly supported sister relationship to the Asian species. Biogeographic analyses confirmed at least five dispersals between Africa and Madagascar, and one between Madagascar and Asia. The rate of endemism for Malagasy Rinorea is in excess of 90%. Phylogenetic and biogeographic analyses reveal that ca. 37% of species have affinities to African relatives and the remaining 63% (i.e., subsect. Verticillatae) are more closely related to Asian species. Several species are critically endangered or presumed extinct, while others are represented by substantial populations in protected areas.
Advisors/Committee Members: Ballard, Harvey E.
Subjects: Biology; Botany
Keywords: Africa; Comoro Islands; Madagascar; Rinorea; Violaceae; phylogeny; biogeography
More Like This
18.
Zhang, Yizhu.
Functional Characterization of Lysine-rich Arabinogalactan-Proteins (AGPs) and an AG Peptide in Arabidopsis.
Degree: PhD, Environmental and Plant Biology (Arts and Sciences), 2008, Ohio University
► The plant cell wall is composed of complex polysaccharides and a small…
(more)
▼ The plant cell wall is composed of complex polysaccharides and a small amount of structural proteins and cell wall enzymes. Arabinogalactan-proteins (AGPs) are highly glycosylated, hydroxyproline-rich structural proteins that play important roles in plant growth and development. AtAGP17, 18 and 19 comprise the lysine-rich classical AGP family in Arabidopsis. They consist of an N-terminal signal peptide, a classical AGP domain disrupted by a short basic lysine-rich subdomain and a C-terminal glycosylphosphatidylinositol (GPI) anchor addition sequence. A previous study showed a null T-DNA insertion mutant of AtAGP19 displayed pleiotropic phenotypes. Here, a microarray approach was employed to elucidate changes in gene expression associated with the atagp19 mutant. The expression of several genes related to cell expansion were found to change significantly. Interestingly, one gene (At1g68720, cytidine/deoxycytidylate deaminase family protein) adjacent to AtAGP19 was found to be down-regulated about 50 fold and RT-PCR showed the absence of mRNA for this gene in the atagp19 mutant. Furthermore, complementation with the 3' portion of the At1g68720 gene can fully restore all the wild type phenotypes, indicating this region is critical for the functions revealed by the agp19 mutant. To examine cellular localization of the lysine-rich AGPs, GFP-AtAGP17/18/19 fusion proteins as well as a GFP control were overexpressed in Arabidopsis plants and the fusion proteins were present on the plant cell surface. Plasmolysis of leaf trichome cells further determined the localization of the fusion proteins at the plasma membrane. Moreover, in vitro pollen germination showed that AtAGP17, unlike LeAGP-1 (the lysine-rich AGP in tomato), was not associated with pollen tube elongation. To further elucidate AtAGP17/18/19 function(s), transgenic Arabidopsis overexpressing AtAGP17/18/19 without the GFP tag were produced. AtAGP18 overexpressors displayed several phenotypes distinct from the wild type plants: they were short and bushy, had short roots and produced less viable seeds. In contrast, the vector control transformants as well as the AtAGP17/19 overexpressors had the same phenotypes as the wild type plants. Furthermore, AtAGP18 was down-regulated by the plant hormone ABA, indicating ABA may be involved in AtAGP18 function(s). Finally, the expression pattern of AtAGP14 (At5g56540), an AG peptide in Arabidopsis was examined. AtAGP14 was highly expressed in flowers and young roots and moderately expressed in seedlings, stems and rosette leaves. A plate-based phenotypic analysis was also carried out for the T-DNA insertional mutant of AtAGP14 and wild type Arabidopsis but no significant differences were observed with respect to germination rate, true leaf numbers, primary root length and lateral root numbers.
Advisors/Committee Members: Showalter, Allan M.
Subjects: Biology; Molecular biology
Keywords: Arabidopsis; arabinogalactan-proteins; lysine-rich AGPs; microarray; overexpression; GPI anchor
More Like This
