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Phylogenetic Studies Of Tribe Cacteae (Cactaceae) With Special Emphasis On The Genus Mammillaria , Charles A. Butterworth Jan 2003

Phylogenetic Studies Of Tribe Cacteae (Cactaceae) With Special Emphasis On The Genus Mammillaria , Charles A. Butterworth

Retrospective Theses and Dissertations

The genus Mammillaria is probably the most species-rich genus in the cactus family. To date, there have been a number of infrageneric classifications of the genus, based largely on morphological data. This study utilized molecular (DNA) sequence data from two chloroplast markers (rpl16 intron and the psbA- trnH intergenic spacer) as part of a cladistic study of the genus. However, in order to allow the choice of a suitable outgroup for Mammillaria an initial study used sequence data from the rpl16 intron to investigate phylogenetic relationships in Tribe Cacteae (to which Mammillaria belongs). The result of that study revealed numerous ...


Local Ecotype Prairie Seed—An Alternative Agricultural Product For Increasing The Viability Of Smaller Farming Operations, Jerry Selby, Donald R. Farrar, Laura Norian Jan 2003

Local Ecotype Prairie Seed—An Alternative Agricultural Product For Increasing The Viability Of Smaller Farming Operations, Jerry Selby, Donald R. Farrar, Laura Norian

Leopold Center Completed Grant Reports

What is the potential for a "prairie truck farm" in Iowa? Investigators tried to determine if it was feasible to establish diverse production plots around the state, with seeds being collected and produced locally, and used as an alternative crop for farmers.


Phylogeny And Morphological Evolution Of The Chenopodiaceae-Amaranthaceae Alliance , Donald B. Pratt Jan 2003

Phylogeny And Morphological Evolution Of The Chenopodiaceae-Amaranthaceae Alliance , Donald B. Pratt

Retrospective Theses and Dissertations

Phylogenetic analysis of plastid encoded ndhF coding sequences for the Chenopodiaceae-Amaranthaceae alliance reveals a monophyletic Chenopodiaceae-Amaranthaceae clade sister to Achatocarpaceae. The Chenopodiaceae-Amaranthaceae-Achatocarpaceae clade is in turn sister to the Caryophyllaceae, the Chenopodiaceae-Amaranthaceae-Achatocarpaceae-Caryophyllaceae clade forming a separate lineage within order Caryophyllales. The Chenopodiaceae as currently circumscribed is paraphyletic and the alliance breaks into a polytomy of four major clades: (i) Amaranthaceae-Polycnemoideae, (ii) Chenopodieae-Atripliceae, (iii) SalicornioideaeSalsoloideae, and (iv) Beteae. Character-state optimizations of morphological characters mapped onto ndhF sequence derived phylogenies reveal phylogenetically significant patterns of character-state distribution. Morphological investigations also revealed a previously undetected branching pattern in the Gomphrenoideae, which is here ...


Dominant Grass Effects On Diversity And Functioning Of Restored Grassland, Brian J. Wilsey Jan 2003

Dominant Grass Effects On Diversity And Functioning Of Restored Grassland, Brian J. Wilsey

Iowa State Research Farm Progress Reports

Native grasslands provide a multitude of benefits to society including forage production, wildlife habitat, and nutrient and CO2 uptake and storage. There has been continuing interest within the conservation community in restoring grasslands to maximize these multiple benefits. In addition to achieving the most common objectives of reducing soil erosion and increasing organic carbon and nutrient availabilities, restored grasslands also produce important wildlife habitat, and they have the potential to uptake and store greenhouse gases like CO2 . Grassland plantings have been found to increase game and non-game bird abundance and diversity and to improve deer habitat.


Molecular Genetic Studies Of Acetyl-Coa Carboxylase And 3-Methylcrotonyl-Coa Carboxylase In Plants , Hui-Rong Qian Jan 2002

Molecular Genetic Studies Of Acetyl-Coa Carboxylase And 3-Methylcrotonyl-Coa Carboxylase In Plants , Hui-Rong Qian

Retrospective Theses and Dissertations

Similar reverse-genetics approach is applied to investigate the function of two biotin-containing enzymes at the interface between catabolism and anabolism: acetyl-CoA carboxylase (ACCase) and 3-methylcrotonyl-CoA carboxylase (MCCase).;Plastidic ACCase catalyzes the first committed step of de novo fatty acid biosynthesis. Antisense Arabidopsis expressing antisense RNA of CAC1-A, which encodes the biotin carboxyl carrier protein (BCCP) of plastidic ACCase under the direction of CaMV 35S promoter, have been obtained. CAC1-A antisense plants with reduced BCCP possess different degrees of similar morphological changes. These include slow growth, smaller plant size, and crinkly and variegated-yellow vegetative and cauline leaves eventually leading to premature ...


Atp-Citrate Lyase Has An Essential Role In Cytosolic Acetyl-Coa Production In Arabidopsis , Beth Leann Fatland Jan 2002

Atp-Citrate Lyase Has An Essential Role In Cytosolic Acetyl-Coa Production In Arabidopsis , Beth Leann Fatland

Retrospective Theses and Dissertations

Acetyl-CoA is both an essential primary and secondary metabolite, however, the source of cytosolic acetyl-CoA has been unclear. We identified two non-overlapping groups of plant cDNAs that encode proteins similar to the amino and carboxy portions of human ATP-citrate lyase. In Arabidopsis, three genes encode the 45 kD ACLA subunit (ACLA-1, At1g10670; ACLA-2, At1g60810; ACLA-3, At1g09430) and two genes encode the 65 kD ACLB subunit (ACLB-1, At3g06650; ACLB-2, At5g49460). Co-expression of ACLA-1 and ACLB-2 cDNAs in Saccharomyces cerevisiae yields ATP-citrate lyase activity, indicating both polypeptides are required for activity. The Arabidopsis holoprotein has a molecular weight of 500 kDa, which ...


Insertional Mutagenesis Of The Signal Transduction Pathway For Low Co2 Acclimation In Chlamydomonas Reinhardtii , Kyujung Van Jan 2001

Insertional Mutagenesis Of The Signal Transduction Pathway For Low Co2 Acclimation In Chlamydomonas Reinhardtii , Kyujung Van

Retrospective Theses and Dissertations

Chlamydomonas reinhardtii shows adaptive changes in order to survive in limiting CO2 conditions because they live in quite variable conditions of CO2 availability. We are trying to identify mutants defective in the acclimation response to limiting CO 2. Nuclear transformation to complement an Arg- phenotype was used to generate insertional mutants, and Cah1 expression and having high CO2-requiring (HCR) phenotype were used as reporters for induction of genes involved in acclimation to limiting CO 2.;Among a collection of insertionally generated mutants, a mutant has been isolated that showed no pCA1 protein and no Cah1 mRNA. This mutant strain, designated ...


The Role Of Small-Scale Disturbances In Structuring The Plant Community Of Native And Reconstructed Prairies , Kelly S. Wolfe-Bellin Jan 2001

The Role Of Small-Scale Disturbances In Structuring The Plant Community Of Native And Reconstructed Prairies , Kelly S. Wolfe-Bellin

Retrospective Theses and Dissertations

Understanding the link between pattern and process is an important goal in ecology, and much research has focused on how small-scale disturbances act to produce spatial patterns in plant communities. In this research, I investigated the role of small-scale disturbances in structuring the plant communities of native and reconstructed prairies, with an explicit emphasis placed on understanding how spatial and temporal patterns in disturbance production affect seedling recruitment.;Two studies investigated the spatial and demographic effects of gopher mound production on four plant species in a native prairie. The spatial distributions of three species were positively related to the pattern ...


Ecology And Restoration Of Farmland Woods In Central Iowa, Donald R. Farrar, Catherine M. Mabry Jan 2001

Ecology And Restoration Of Farmland Woods In Central Iowa, Donald R. Farrar, Catherine M. Mabry

Leopold Center Completed Grant Reports

The researchers studied the distribution and abundance of the plant species of farmland woodlots in central Iowa, with particular emphasis on the differences in species composition between sites currently or recently grazed by cattle versus those that had not been grazed for more than 50 years. In addition, various attributes of common species and less common (restricted) species were compared.


Carbohydrate Regulation Of Leaf Development: Investigating The Role Of Source Strength, Carbon Partitioning And Hexokinase Signaling In Regulating Leaf Senescence , Adam Christopher Miller Jan 2000

Carbohydrate Regulation Of Leaf Development: Investigating The Role Of Source Strength, Carbon Partitioning And Hexokinase Signaling In Regulating Leaf Senescence , Adam Christopher Miller

Retrospective Theses and Dissertations

For many plants, growth in elevated CO2 leads to reduced rates of photosynthesis. To examine the role leaf ontogeny plays in acclimation; we monitored photosynthesis and some related parameters throughout the development of tobacco leaves under ambient and high CO2 conditions. The pattern of photosynthetic rate over time was consistent with the expected pattern for a typical dicot leaf for both. However, the photosynthesis pattern in high-CO2-grown tobacco was shifted temporally to an earlier maximum and subsequent senescent decline. Rubisco activity appeared to be the main factor regulating photosynthetic rates in both treatments. Therefore, we propose a new model for ...


The Influence Of Vegetation And Landscape On The Forest Bird Community Of Northeast Iowa , William Russell Norris Jan 1999

The Influence Of Vegetation And Landscape On The Forest Bird Community Of Northeast Iowa , William Russell Norris

Retrospective Theses and Dissertations

I studied bird community dynamics and habitat associations of forest birds in northeast Iowa in 1995 and 1996. During this study, 107 different bird species were detected in northeast Iowa forests, including many neotropical migrant songbirds. However, a nest parasite, the brown-headed cowbird ( Molothrus ater), was the most frequently detected bird during this study. The abundance and species richness of birds (both expressed as mean numbers per bird census point at each site) were both higher in 1995 but the rank orders of bird species in 1995 and 1996 were highly correlated, suggesting stable bird community structure over time;Most ...


The Positional Cloning And Expression Studies Of The Immutans Variegation Locus Of Arabidopsis Thaliana , Dongying Wu Jan 1999

The Positional Cloning And Expression Studies Of The Immutans Variegation Locus Of Arabidopsis Thaliana , Dongying Wu

Retrospective Theses and Dissertations

immutans (im), a nuclear gene induced variegation mutation of Arabidopsis, causes green- and white-sectored leaves and is recessive. The green sectors contain cells with normal chloroplasts, whereas the white sectors are heteroplastidic and contain cells with abnormal, pigment-deficient plastids as well as some normal chloroplasts. The white sectors accumulate the carotenoid precursor phytoene. We have cloned IM by chromosome walking and found that the gene encodes a 40.5-kD chloroplast thylakoid membrane protein with sequence motifs characteristic of alternative oxidase, a mitochondrial protein that functions as a terminal oxidase in the respiratory chains of all plants. IM protein functions as ...


Evolution Of The Alcohol Dehydrogenase Gene Family In Diploid And Tetraploid Gossypium L , Randall Lee Small Jan 1999

Evolution Of The Alcohol Dehydrogenase Gene Family In Diploid And Tetraploid Gossypium L , Randall Lee Small

Retrospective Theses and Dissertations

Molecular data have had a profound effect on the field of plant evolutionary biology, yet the potential wealth of data stored in low-copy nuclear-encoded genes has been virtually ignored, relative to studies of chloroplast and ribosomal DNA. In this dissertation I present an analysis of a model nuclear-encoded gene family (alcohol dehydrogenase, Adh) in a model organismal system, the cotton genus (Gossypium L., Malvaceae);A combination of PCR- and Southern hybridization-based approaches was employed to isolate, sequence, and map multiple Adh gene family members. Diploid Gossypium contain at least seven Adh loci. Sequence analysis reveals extensive intron variation between loci ...


Molecular Phylogeny Of The Portulacaceous Cohort , Wendy Linn Applequist Jan 1999

Molecular Phylogeny Of The Portulacaceous Cohort , Wendy Linn Applequist

Retrospective Theses and Dissertations

The central focus of this research is the use of chloroplast ndhF sequence data to produce a phylogeny of the Portulacaceae, including an evaluation of the relationships of this family to the Basellaceae, Cactaceae, and Didiereaceae. This cohort was divided into two major clades, both including genera of the Portulacaceae; the Cactaceae were derived from the first, and the Basellaceae and Didiereaceae from the second. Within the latter, a largely Western American assemblage of genera, some formerly identified as basal taxa, was found to be monophyletic. This phylogeny indicated that all recent infrafamilial classifications of the Portulacaceae were flawed by ...


Evaluation Of The Impact Of Tillage/Cropping Systems On Soil Microflora And Week Seedbank Predation, Micheal D. K. Owen, Joel Felix, Robert G. Hartzler, Thomas E. Loynachan, L. H. Tiffany, Thomas B. Moorman Jan 1999

Evaluation Of The Impact Of Tillage/Cropping Systems On Soil Microflora And Week Seedbank Predation, Micheal D. K. Owen, Joel Felix, Robert G. Hartzler, Thomas E. Loynachan, L. H. Tiffany, Thomas B. Moorman

Leopold Center Completed Grant Reports

Soil erosion and pesticide use are critical issues in sustainable agriculture. With a view to decreasing the amount of pesticides used for weed control, researchers assessed the impact of tillage, cropping systems and weed management regimes on seasonal and long-term weed and weed seedbank population dynamics, especially in Conservation Reserve Program land being returned to production.


Constructed Wetlands To Reduce Agricultural Chemical Transport To Water Resources, William G. Crumpton, James L. Baker, Stephen W. Fisher, B. Hecht, Jana Z. Stenback, C. Zmolek, Stewart W. Melvin, Dean W. Lemke Jan 1999

Constructed Wetlands To Reduce Agricultural Chemical Transport To Water Resources, William G. Crumpton, James L. Baker, Stephen W. Fisher, B. Hecht, Jana Z. Stenback, C. Zmolek, Stewart W. Melvin, Dean W. Lemke

Leopold Center Completed Grant Reports

This project was part of a larger five-year, multi-phase research and demonstration effort to study water quality and agricultural drainage wells (ADWs). The goal was to evaluate the use of constructed wetlands for treatment of subsurface drainage prior to release to groundwater through ADWs and to develop design and operation criteria for these treatment wetlands.


Biochemical Characterization And Positional Cloning Of The Var2 Variegation Mutant Of Arabidopsis Thaliana , Meng Chen Jan 1999

Biochemical Characterization And Positional Cloning Of The Var2 Variegation Mutant Of Arabidopsis Thaliana , Meng Chen

Retrospective Theses and Dissertations

Chloroplasts differentiation and development are highly coordinated with their host cells. To better elucidate the mechanisms involved in nuclear-chloroplast interactions, we characterized a nuclear encoded leaf variegation mutation called var2. While cotyledons appear normal, true leaves of var2 emerge as yellow, then turn into green-white sectors. The green sectors contain cells with normal chloroplasts, whereas the white sectors contain cells with abnormal plastid lacking of internal membrane structures. The phenotypes suggested that VAR2 might be involved in thylakoid biogenesis in early chloroplast differentiation. We cloned the VAR2 gene by a map-based method. Five original and two potential alleles were sequenced ...


Molecular Systematics In Gossypium And Its Relatives , Tosak Seelanan Jan 1998

Molecular Systematics In Gossypium And Its Relatives , Tosak Seelanan

Retrospective Theses and Dissertations

Gossypium L. is an economically important genus as it harbors four species that provide the cotton of commerce. Although many aspects of the evolution and taxonomy of Gossypium are well understood, there has been little work devoted to assessing relationships among Gossypium and its allied genera. In addition, newly discovered species, of Gossypium sect. Grandicalyx from Australia, have prompted a need for more research into the phylogeny of these new species and their relationships to other Gossypium taxa. Multiple data sets were used to address questions regarding (1) phylogenetic relationships among Gossypium and its relatives, and (2) the phylogeny and ...


Nodulation And Expression Of The Early Nodulation Gene, Enod2, In Temperate Woody Legumes Of The Papilionoideae , Carol Marie Foster Jan 1998

Nodulation And Expression Of The Early Nodulation Gene, Enod2, In Temperate Woody Legumes Of The Papilionoideae , Carol Marie Foster

Retrospective Theses and Dissertations

Understanding dinitrogen-fixing symbioses in economically important, temperate, woody legumes requires evaluating their nodulation status and studying molecular mechanisms of nodulation and dinitrogen fixation. Styphnolobium japonicum (L.) Schott and Cladrastis kentukea (Dum.-Cours.) Rudd were examined for the capacity to form root nodules. Inoculations with various broad-range rhizobia, soil and rhizobia from closely related species of Sophora, and soil from S. japonicum and C. kentukea in Japan, China, and the United States did not elicited nodulation. As an unexpected consequence of these experiments, rhizobia were isolated for the first time from nodules of Maackia floribunda Takeda, and most tested isolates also ...


Enhancement Of Agricultural Weed Control By Manipulation Of The Light Environment, Thomas W. Jurik Jan 1998

Enhancement Of Agricultural Weed Control By Manipulation Of The Light Environment, Thomas W. Jurik

Leopold Center Completed Grant Reports

Studies suggest that emergence of weed seedlings can be diminished by decreasing the exposure of seeds to light during tillage. Field studies conducted near Ames, Iowa, tested the effect of excluding light during tillage on emergence of common weed species of central Iowa. Plots were tilled Botany either during the day, during the day with implements covered, at night, or at night with implements covered, and subsequent seed emergence was monitored. The effect of brief exposure to light on germination of weed seeds under controlled laboratory conditions was also studied.


Molecular Evolution At Homoeologous Loci In Allotetraploid Cotton (Malvaceae: Gossypium Hirsutum L) , Richard Clark Cronn Jan 1997

Molecular Evolution At Homoeologous Loci In Allotetraploid Cotton (Malvaceae: Gossypium Hirsutum L) , Richard Clark Cronn

Retrospective Theses and Dissertations

Duplicated genes created during polyploid formation ('homoeologues') may experience a variety of fates depending upon the evolutionary forces operating on these loci. Homoeologue divergence may be limited if selection operates to maintain duplicate gene function, or divergence may be permitted if selective pressure on a functionally redundant locus is relaxed. In an attempt to determine the fate of duplicate loci in a polyploid genome, I have isolated and described sequence evolution at 15 sets of homoeologous loci from allotetraploid cotton (Gossypium L.) and the corresponding orthologues from its progenitor diploid genomes. Homoeology and orthology relationships of these loci have been ...


Analyses Of A Genic Male-Sterile Mutant In Soybean , Wei Jin Jan 1997

Analyses Of A Genic Male-Sterile Mutant In Soybean , Wei Jin

Retrospective Theses and Dissertations

A new genic male-sterile mutant in soybean was characterized genetically, developmentally, and molecularly. This mutant is controlled by a single recessive gene, which is not allelic to six previously identified soybean genic male-sterile mutants: ms1, ms2, ms3, ms4, ms5, or ms6. No linkage was detected between the male-sterile gene and flower color (W1 locus), or between the male-sterile gene and pubescence color (T1 locus). Developmental and enzymatic studies showed that sterility was caused by retention of the callose walls, which normally are degraded by callase ([beta]-1,3-glucanase) at the late tetrad stage. Molecular markers linked with the male-sterile gene ...


A Phylogenetic Study Of Ferocactus Britton And Rose (Cactaceae: Cactoideae) , Jorge Hugo Cota-Sánchez Jan 1997

A Phylogenetic Study Of Ferocactus Britton And Rose (Cactaceae: Cactoideae) , Jorge Hugo Cota-Sánchez

Retrospective Theses and Dissertations

Ferocactus is the third largest genus in the tribe Cacteae of the Cactoideae, and the number of species is still matter of taxonomic discussion. The different interpretation of morphological characters has led to discrepancies in species boundaries. This dissertation includes four papers describing the taxonomic history of Ferocactus to elucidate its evolutionary history and phylogenetic relationships with related taxa of the tribe Cacteae. The first paper is a general review of Ferocactus and summarizes the knowledge of the genus and discusses the relevance of understanding its phylogenetic relationships at the specific, generic and tribal levels. The second paper is a ...


Expression Of Genes Encoding Acetyl-Coa Carboxylase, Biotin Synthase, And Acetyl-Coa Generating Enzymes In Arabidopsis Thaliana , Jinshan Ke Jan 1997

Expression Of Genes Encoding Acetyl-Coa Carboxylase, Biotin Synthase, And Acetyl-Coa Generating Enzymes In Arabidopsis Thaliana , Jinshan Ke

Retrospective Theses and Dissertations

Acetyl-CoA carboxylase catalyzes the formation of malonyl-CoA from acetyl-CoA. The four genes encoding heteromeric acetyl-CoA carboxylase are coordinately expressed in leaves, flowers, and developing siliques and embryos. The highest expression occurs in tissues undergoing rapid growth and high oil deposition. The gene encoding the E1 [beta] subunit of chloroplastidic pyruvate dehydrogenase has an identical pattern, indicating it may provide acetyl-CoA for seeds. In contrast, the gene encoding acetyl-CoA synthetase has a different expression pattern and is expressed at low levels in seeds;The ACC1 genes encoding homomeric acetyl-CoA shows transient expression in a variety of cell types. The homomeric acetyl-CoA ...


Vegetation Dynamics In Prairie Wetlands , Eric William Seabloom Jan 1997

Vegetation Dynamics In Prairie Wetlands , Eric William Seabloom

Retrospective Theses and Dissertations

I designed and implemented three studies exploring the factors controlling the development of vegetative zonation in prairie wetlands. In the first study, I used growth chamber experiments to examine the effects of water depth and temperature on seedling recruitment from a wetland seed bank. Regression analysis indicated that both water depth and temperature affected the composition of the seedling community. Annual species richness declined in richness. Perennial species richness increased in richness with decreasing temperature. Species that were found in deep water as adults germinated at higher rates in the flooded treatments, while species that occurred at higher elevations as ...


Genetic Characterization Of Northern Flints And Flours Maize (Zea Mays L. Spp. Mays) With Isozyme, Ssr, And Morphological Markers, William Gerardo González Ugalde Jan 1997

Genetic Characterization Of Northern Flints And Flours Maize (Zea Mays L. Spp. Mays) With Isozyme, Ssr, And Morphological Markers, William Gerardo González Ugalde

Retrospective Theses and Dissertations

The Northern Flints and Flours (NF), one of the more important races for maize breeders and scientists, is one of the progenitors of Corn Belt Dents (CB). Despite its importance this race is not well-characterized. Therefore, an assessment of the utility of different methods for genetic characterization of the NF was conducted. Genetic variation in 40 representative germplasm accessions of the racial groups NF, CB, and Southern Dents (SD), maize from the southwestern US and northern Mexico, and maize intermediate between the NF and the other groups, were evaluated with morphological, isozyme and SSR markers. SSR loci proved to be ...


The Role Of Arbuscular Mycorrhizal Fungi In Prairie Wetlands , Paul Robert Wetzel Jan 1996

The Role Of Arbuscular Mycorrhizal Fungi In Prairie Wetlands , Paul Robert Wetzel

Retrospective Theses and Dissertations

Research on arbuscular mycorrhizal fungi (AMF) suggests that their effect on plant growth is a continuum that changes from positive to negative along environmental gradients as conditions for plant growth improve. Prairie wetlands were used to test this mycorrhizal continuum model. First, three saline and three freshwater wetlands were surveyed for AMF, to investigate the hypothesis that AMF colonization would be greater in wetlands with high soil salinity, lower nutrient levels, and during periods of drought. Second, a greenhouse experiment on Carex stricta and Calamagrostis canadensis tested whether AMF improved plant growth and nutrient uptake under five hydrologic regimes. Third ...


Coexistence Of Two Floating-Leaved Species, Nymphoides Indica And Nymphoides Cristata, And The Role Of Seed Banks In Vegetation Dynamics At The Keleodeo National Park Wetlands, Bharatpur, India , Daniel Harry Mason Jan 1996

Coexistence Of Two Floating-Leaved Species, Nymphoides Indica And Nymphoides Cristata, And The Role Of Seed Banks In Vegetation Dynamics At The Keleodeo National Park Wetlands, Bharatpur, India , Daniel Harry Mason

Retrospective Theses and Dissertations

Life history characteristics of two floating-leaved species, Nymphoides cristata (Roxb.) O. Kuntze and N. indica (L.) O. Kuntze, were investigated. The purpose of the study was to determine why N. cristata is common in wetlands with an annual drawdown, and N. indica in permanently inundated wetlands. Life history characteristics were studied in the field and along a water gradient in a concrete tank. In a second study, 20 monsoonal wetlands were sampled for their seed banks and vegetation. These studies were conducted at the Keoladeo National Park, Bharatpur, India;N. cristata is favored under drawdown conditions because of greater survival ...


Phylogeny And Classification Of The Bamboos (Poaceae: Bambusoideae) Based On Molecular And Morphological Data , Wei-Ping Zhang Jan 1996

Phylogeny And Classification Of The Bamboos (Poaceae: Bambusoideae) Based On Molecular And Morphological Data , Wei-Ping Zhang

Retrospective Theses and Dissertations

Chloroplast ndhF gene sequences and morphological and leaf anatomical characters were analyzed separately and as combined data sets to reconstruct the phylogeny of subfamily Bambusoideae. The analyses further confirmed that the monophyletic bambusoid clade consists of only two monophyletic lineages: the woody bamboos, and the herbaceous olyroid bamboos. Buergersiochloa was resolved as the basal lineage in the herbaceous olyroids, whereas Pariana/Eremitis was sister to the rest of the olyroids. The woody bamboos were divided into two main groups: temperate woody bamboos and tropical woody bamboos; and the tropical clade was further subdivided along geographic lines into the Old World ...


The Ecology Of Dicranopteris Linearis On Windward Mauna Loa, Hawai'i, Usa , Ann Elizabeth Russell Jan 1996

The Ecology Of Dicranopteris Linearis On Windward Mauna Loa, Hawai'i, Usa , Ann Elizabeth Russell

Retrospective Theses and Dissertations

Dicranopteris linearis (Gleicheniaceae), a climbing, mat-forming fern, dominates >42,000 ha of Hawaiian rainforests. One main objective was to determine the relative importance of this native species in intact, natural rainforest ecosystems on windward Mauna Loa, Hawai'i. The second goal was to examine this species' functional attributes and genetic diversity, and to relate them to natural distribution patterns over an elevational range of 290 to 1660 m on primary successional substrates of two different ages, 136 and ~3400 years old;Dicranopteris' clonal growth form, marcescent leaves, and high phosphorus use efficiency, combined with a short, <1 year, leaf segment lifespan make this species highly competitive in colonizing open canopy, low soil fertility, and intermittently waterlogged sites, i.e., conditions typical of early primary successional and post-dieback sites on the pahoehoe and a'a lava substrates;Colonization of a primary successional site by this species probably consists of two phases: (1) initial establishment by sexual reproduction via outcrossing during the first ~100 years, followed by (2) vegetative growth in the two to four clones established over a 0.5-ha area;Dicranopteris contributes up to 74% of the aboveground net primary productivity (ANPP), whereas it contains only 0-14% of the biomass. Dicranopteris litter decomposition rates are very low, with ≥50% of the original leaf mass remaining after two years. Therefore, Dicranopteris is a substantial contributor to soil detrital pools. At the ecosystem-level, Dicranopteris accounts for up to 57% and 47% of the nitrogen and phosphorus uptake, respectively, whereas it contains only 0-24% and 0-30% of the respective masses of N and P. Dicranopteris facilitates small inputs of nitrogen via asymbiotic nitrogen fixation to these nitrogen-limited sites;Growth in the overstory dominant, Metrosideros, increased upon removal of Dicranopteris from a young-flow site at 290 m. However, 43% of the understory area was bare soil three years after removal. Therefore, Dicranopteris may be the only native species capable of vegetating the understory. In the absence of Dicranopteris, an apparent vacuum is created which could be filled by a non-native invader. Thus, Dicranopteris' most important role may be to resist the invasion of exotic species into unique Hawaiian rainforests.