1,089 research outputs found

    Floristic response to urbanization: Filtering of the bioregional flora in Indianapolis, Indiana, USA

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    PREMISE OF THE STUDY: Globally, urban plant populations are becoming increasingly important, as these plants play a vital role in ameliorating effects of ecosystem disturbance and climate change. Urban environments act as filters to bioregional flora, presenting survival challenges to spontaneous plants. Yet, because of the paucity of inventory data on plants in landscapes both before and after urbanization, few studies have directly investigated this effect of urbanization. METHODS: We used historical, contemporary, and regional plant species inventories for Indianapolis, Indiana USA to evaluate how urbanization filters the bioregional flora based on species diversity, functional traits, and phylogenetic community structure. KEY RESULTS: Approximately 60% of the current regional flora was represented in the Indianapolis flora, both historically and presently. Native species that survived over time were significantly different in growth form, life form, and dispersal and pollination modes than those that were extirpated. Phylogenetically, the historical flora represented a random sample of the regional flora, while the current urban flora represented a nonrandom sample. Both graminoid habit and abiotic pollination are significantly more phylogenetically conserved than expected. CONCLUSIONS: Our results likely reflect the shift from agricultural cover to built environment, coupled with the influence of human preference, in shaping the current urban flora of Indianapolis. Based on our analyses, the urban environment of Indianapolis does filter the bioregional species pool. To the extent that these filters are shared by other cities and operate similarly, we may see increasingly homogenized urban floras across regions, with concurrent loss of evolutionary information

    The Achievement Gap from the Student\u27s Perspective

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    African American students disproportionately perform poorly compared to their peers academically. This research project reviews previous findings for causes of the achievement gap. Race, Socioeconomic Status, Family and High Quality Teaching/Schools were the recurrent themes in the existing research. A qualitative research method was used to discern the barriers to graduating high school on time from the student’s perspective. Semi structured qualitative interviews were used to conduct research about why students did not graduate high school. The sample for this study included seven adult male participants who did not graduate high school. Overall, the research showed that participants agreed with previous literature. Participants generally did not think that their parents or school supported their education. The majority of participants also thought that their family’s income impacted their learning negatively. The implications of this project invite continued research on why being mobile and poor impact education negatively. Further research also needs to be conducted to identify what students and families affected by the achievement gap identify as areas that need improvement and how it has affected them. Implications for education are to offer a culturally sensitive curriculum to students and provide individualized instruction to students identified as struggling

    The Achievement Gap from the Student\u27s Perspective

    Get PDF
    African American students disproportionately perform poorly compared to their peers academically. This research project reviews previous findings for causes of the achievement gap. Race, Socioeconomic Status, Family and High Quality Teaching/Schools were the recurrent themes in the existing research. A qualitative research method was used to discern the barriers to graduating high school on time from the student’s perspective. Semi structured qualitative interviews were used to conduct research about why students did not graduate high school. The sample for this study included seven adult male participants who did not graduate high school. Overall, the research showed that participants agreed with previous literature. Participants generally did not think that their parents or school supported their education. The majority of participants also thought that their family’s income impacted their learning negatively. The implications of this project invite continued research on why being mobile and poor impact education negatively. Further research also needs to be conducted to identify what students and families affected by the achievement gap identify as areas that need improvement and how it has affected them. Implications for education are to offer a culturally sensitive curriculum to students and provide individualized instruction to students identified as struggling

    Full-field structured-illumination super-resolution X-ray transmission microscopy

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    Modern transmission X-ray microscopy techniques provide very high resolution at low and medium X-ray energies, but suffer from a limited field-of-view. If sub-micrometre resolution is desired, their field-of-view is typically limited to less than one millimetre. Although the field-of-view increases through combining multiple images from adjacent regions of the specimen, so does the required data acquisition time. Here, we present a method for fast full-field super-resolution transmission microscopy by structured illumination of the specimen. This technique is well-suited even for hard X-ray energies above 30 keV, where efficient optics are hard to obtain. Accordingly, investigation of optically thick specimen becomes possible with our method combining a wide field-of-view spanning multiple millimetres, or even centimetres, with sub-micron resolution and hard X-ray energies

    Chromosome Number Changes Associated with Speciation in Sedges: a Phylogenetic Study in Carex section Ovales (Cyperaceae) Using AFLP Data

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    Phylogenetic analysis of amplified fragment length polymorphisms (AFLP) was used to infer patterns of morphologic and chromosomal evolution in an eastern North American group of sedges (ENA clade I of Carex sect. Ovales). Distance analyses of AFLP data recover a tree that is topologically congruent with previous phylogenetic estimates based on nuclear ribosomal DNA (nrDNA) sequences and provide support for four species groups within ENA clade I. A maximum likelihood method designed for analysis of restriction site data is used to evaluate the strength of support for alternative topologies. While there is little support for the precise placement of the root, the likelihood of topologies in which any of the four clades identified within the ENA clade I is forced to be paraphyletic is much lower than the likelihood of the optimal tree. Chromosome counts for a sampling of species from throughout sect. Ovales are mapped onto the tree, as well as counts for all species in ENA clade I. Parsimony reconstruction of ancestral character states suggest that: (1) Heilborn’s hypothesis that more highly derived species in Carex have higher chromosome counts does not apply within sect. Ovales, (2) the migration to eastern North America involved a decrease in average chromosome count within sect. Ovales, and (3) intermediate chromosome counts are ancestral within ENA clade I. A more precise understanding of chromosomal evolution in Carex should be possible using likelihood analyses that take into account the intraspecific polymorphism and wide range of chromosome counts that characterize the genus

    Isolation of 11 Polymorphic Tri- and Tetranucleotide Microsatellite Loci in a North American Sedge (\u3ci\u3eCarex scoparia\u3c/i\u3e: Cyperaceae) and Cross-Species Amplification in Three Additional \u3ci\u3eCarex\u3c/i\u3e Species

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    We report on the isolation and evaluation of 11 microsatellites from a widespread eastern North American wetland sedge, Carex scoparia. Loci exhibit 3–9 alleles over five populations and significant FIS (0.204–0.717) in most populations. All primers cross-amplify in at least two other species, and 10 cross-amplify in the more distantly related C. stipata. These markers will be used to examine population genetics and patterns of chromosomal diversification in this ecologically important sedge species and its relatives

    Phylogeny and biogeography of Croton alabamensis (Euphorbiaceae), a rare shrub from Texas and Alabama, using DNA sequence and AFLP data

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    Croton alabamensis (Euphorbiaceae s.s. ) is a rare plant species known from several populations in Texas and Alabama that have been assigned to var. texensis and var. alabamensis , respectively. We performed maximum parsimony, maximum likelihood, and Bayesian analyses of DNA sequences from the nuclear ribosomal internal transcribed spacer (ITS) and 5.8S regions and chloroplast trn L- trn F regions from collections of the two varieties of C. alabamensis and from outgroup taxa. C. alabamensis emerges alone on a long branch that is sister to Croton section Corylocroton and the Cuban endemic genus Moacroton . Molecular clock analysis estimates the split of C. alabamensis from its closest relatives in sect. Corylocroton at 41 million years ago, whereas the split of the two varieties of C. alabamensis occurred sometime in the Quaternary. Amplified fragment length polymorphism (AFLP) analyses were performed using two selective primer pairs on a larger sampling of accessions (22 from Texas, 17 from Alabama) to further discriminate phylogenetic structure and quantify genetic diversity. Using both neighbour joining and minimum evolution, the populations from the Cahaba and Black Warrior watersheds in Alabama form two well-separated groups, and in Texas, geographically distinct populations are recovered from Fort Hood, Balcones Canyonlands, and Pace Bend Park. Most of the molecular variance is accounted for by variance within populations. Approximately equal variance is found among populations within states and between states (varieties). Genetic distance between the Texas populations is significantly less than genetic distance between the Alabama populations. Both sequence and AFLP data support the same relationships between the varieties of C. alabamensis and their outgroup, while the AFLP data provide better resolution among the different geographical regions where C. alabamensis occurs. The conservation implications of these findings are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72311/1/j.1365-294X.2006.02970.x.pd

    Crop Rotations in the Brazos River Valley.

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    20 p
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