Systematic relationships in the narrow-leaved species of chenopodium of the Western United States

Brittonia - In a study of ten taxa ofChenopodium occurring primarily in the western United States and designated as the narrow-leaved complex, data from morphology, flavonoid chemistry, and somatic...     

A statistical analysis of sixteen taxa of rhynchosia (Leguminosae) in the United States

Sixteen taxa were classified using 20 characters. Similarity between pairs of taxa for each character was based upon non-significance of their respective means using Duncan’s Multiple Range Test at the five percent level. The results are presented in the form of a similarity matrix and a phenogram. This study suggests that there are three major sub-groups within the genus.     

Limnological Aspects of Some Early Explorations in the Western United States

SYNOPSIS. Limnology was not recognized as a distinct scienceat the time of the great post-Civil War western explorationsof Hayden, Wheeler, King, and Powell. However, these and someearlier explorations made observations in certain branches ofnatural science that would become integral parts of limnologicalscience. In keeping with what was known at the time, some exploringparties made observations and collections, such as water temperatureor water samples and larger invertebrates, which could be readilyaccomplished by hand or with simple equipment. The inconvenienceof carrying or expending time to build boats for offshore usemay have seriously deterred limnological work.     

The structure of common genetic variation in United States populations

The common-variant/common-disease model predicts that most risk alleles underlying complex health-related traits are common and, therefore, old and found in multiple populations, rather than being rare or population specific. Accordingly, there is widespread interest in assessing the population structure of common alleles. However, such assessments have been confounded by analysis of data sets with bias toward ascertainment of common alleles (e.g., HapMap and Perlegen) or in which a relatively small number of genes and/or populations were sampled. The aim of this study was to examine the structure of common variation ascertained in major U.S. populations, by resequencing the exons and flanking regions of 3,873 genes in 154 chromosomes from European, Latino/Hispanic, Asian, and African Americans generated by the Genaissance Resequencing Project. The frequency distributions of private and common single-nucleotide polymorphisms (SNPs) were measured, and the extent to which common SNPs were shared across populations was analyzed using several different estimators of population structure. Most SNPs that were common in one population were present in multiple populations, but SNPs common in one population were frequently not common in other populations. Moreover, SNPs that were common in two or more populations often differed significantly in frequency from one population to another, particularly in comparisons of African Americans versus other U.S. populations. These findings indicate that, even if the bulk of alleles underlying complex health-related traits are common SNPs, geographic ancestry might well be an important predictor of whether a person carries a risk allele.     

Large branchiopod assemblages common to Mexico and the United States

Cu, Cd, Zn and Pb concentrations in both dissolved andparticulate phase were assessed during 1995. DataQuality Assurance was an integral part of this studyand involved all major steps of the analysis proceduresuch as sampling, sample handling, preconcentrationand determination. Desorption and redox processes clearly control thedissolved Cu and Cd profiles. Mobilisation ofdissolved Zn is small and essentially restricted tothe low salinity area and the late spring survey.Dissolved Pb shows the clearest dilution pattern. Theparameters representative of these processes(dissolved oxygen and salinity) also correlate verywell with the particulate metal profiles. In addition, the plankton activity (expressed by thechlorophyll-a levels) may influence the dissolved andparticulate metal profiles. In combination withdesorption and redox processes, seasonal variationswere induced. This revised version was published online in July 2006 with corrections to the Cover Date.     

New reports of nuclear DNA content for 407 vascular plant taxa from the United States

Background and Aims

The amount of DNA in an unreplicated haploid nuclear genome (C-value) ranges over several orders of magnitude among plant species and represents a key metric for comparing plant genomes. To extend previously published datasets on plant nuclear content and to characterize the DNA content of many species present in one region of North America, flow cytometry was used to estimate C-values of woody and herbaceous species collected in Wisconsin and the Upper Peninsula of Michigan, USA.

Methods

A total of 674 samples and vouchers were collected from locations across Wisconsin and Michigan, USA. From these, C-value estimates were obtained for 514 species, subspecies and varieties of vascular plants. Nuclei were extracted from samples of these species in one of two buffers, stained with the fluorochrome propidium iodide, and an Accuri C-6 flow cytometer was used to measure fluorescence peaks relative to those of an internal standard. Replicate extractions, coefficients of variation and comparisons to published C-values in the same and related species were used to confirm the accuracy and reliability of our results.

Key Results and Conclusions

Prime C-values for 407 taxa are provided for which no published data exist, including 390 angiosperms, two gymnosperms, ten monilophytes and five lycophytes. Non-prime reports for 107 additional taxa are also provided. The prime values represent new reports for 129 genera and five families (of 303 genera and 97 families sampled). New family C-value maxima or minima are reported for Betulaceae, Ericaceae, Ranunculaceae and Sapindaceae. These data provide the basis for phylogenetic analyses of C-value variation and future analyses of how C-values covary with other functional traits.     

Building regional threat-based networks for estuaries in the Western United States

Estuaries are ecologically and economically valuable and have been highly degraded from both land and sea. Estuarine habitats in the coastal zone are under pressure from a range of human activities. In the United States and elsewhere, very few conservation plans focused on estuaries are regional in scope; fewer still address threats to estuary long term viability.We have compiled basic information about the spatial extent of threats to identify commonalities. To do this we classify estuaries into hierarchical networks that share similar threat characteristics using a spatial database (geodatabase) of threats to estuaries from land and sea in the western U.S. Our results show that very few estuaries in this region (16%) have no or minimal stresses from anthropogenic activity. Additionally, one quarter (25%) of all estuaries in this study have moderate levels of all threats. The small number of un-threatened estuaries is likely not representative of the ecological variability in the region and will require working to abate threats at others. We think the identification of these estuary groups can foster sharing best practices and coordination of conservation activities amongst estuaries in any geography.     

Geomicrobiological Changes in Two Ephemeral Desert Playa Lakes in the Western United States

The geochemistry and microbiology of two ephemeral playa lakes in the Western United States, Surprise Valley Alkali Lake (SVAL) and Eldorado Playa (EP), were examined over one wetting cycle, revealing dramatic temporal changes in suspended mineralogy, aqueous chemistry, and bacterial populations. In SVAL the predominant suspended mineral changed from smectite to vermiculite and clinoptilolite, which led to a depletion of soluble Mg²⁺. Nitrate became depleted in both playas as a result of biological nitrogen demand imparted by unusually dense microbial communities reaching ～1 × 10⁸ cultivable heterotrophs per ml of water. One hundred eighty eight bacterial isolates were obtained, representing sixty phylotypes and four phyla: Actinobacteria, Bacteroidetes, Proteobacteria, and Firmicutes. Phylogenetic analyses suggested that the microbial communities reflected different phases of succession, with SVAL changing from a diverse community with abundant Yonghaparkia to a less diverse late summer community with abundant Bacteroidetes and Proteobacteria such as Loktanella, Rhodobaca, Saccharospirillum, Flexibacter, and phylogenetically novel members of the Flexibacteriaceae. In EP, a diverse assemblage of bacteria often associated with soils was replaced very quickly by a much less even community dominated by Yonghaparkia, Sandarakinorhabdus, and relatives of Belliella baltica. Strikingly, the early summer microbial community from SVAL was not significantly different from the EP community that developed within one week of flooding, even though these playas are almost 1000 km apart, whereas sympatric communities in different phases of succession were different. To our knowledge, this is one of the first geomicrobiological studies of a recharge playa, the dominant playa type worldwide.     

Distribution and Abundance of Saltcedar and Russian Olive in the Western United States

Over the past century, two introduced Eurasian trees, saltcedar (Tamarix spp.) and Russian olive (Elaeagnus angustifolia) have become wide spread on western United States of American (U.S.) rivers. This paper reviews the literature on the following five key areas related to their distribution and abundance in the western United States: (1) the history of introduction, planting, and spread of saltcedar and Russian olive; (2) their current distribution; (3) their current abundance; (4) factors controlling their current distribution and abundance; and (5) models that have been developed to predict their future distribution and abundance. Saltcedar and Russian olive are now the third and fourth most frequently occurring woody riparian plants and the second and fifth most abundant species (out of 42 native and non-native species) along rivers in the western United States. Currently there is not a precise estimate of the areas that these species occupy in the entire West. Climatic variables are important determinants of their distribution and abundance. For example, saltcedar is limited by its sensitivity to hard freezes, whereas Russian olive appears to have a chilling requirement for bud break and seed germination, and can presumably survive colder winter temperatures. Either species can be dominant, co-dominant or sub-dominant relative to native species on a given river system. A number of environmental factors such as water availability, soil salinity, degree of streamflow regulation, and fire frequency can influence the abundance of these species relative to native species. Numerous studies suggest that both species have spread on western rivers primarily through a replacement process, whereby stress-tolerant species have moved into expanded niches that are no longer suitable for mesic native pioneer species. Better maps of current distribution and rigorous monitoring of distributional changes though time can help to resolve differences in predictions of potential future spread. An adequate understanding does not yet exist of what fraction of western riparian zones is resistant to dominance by either of these species, what fraction is at risk and could benefit from intervention, and what fraction has been altered to the point that saltcedar or Russian olive are most likely to thrive.     

A mutation causing Alport syndrome with tardive hearing loss is common in the western United States.

Mutations in the COL4A5 gene, located at Xq22, cause Alport syndrome (AS), a nephritis characterized by progressive deterioration of the glomerular basement membrane and usually associated with progressive hearing loss. We have identified a novel mutation, L1649R, present in 9 of 121 independently ascertained families. Affected males shared the same haplotype of eight polymorphic markers tightly linked to COL4A5, indicating common ancestry. Genealogical studies place the birth of this ancestor >200 years ago. The L1649R mutation is a relatively common cause of Alport syndrome in the western United States, in part because of the rapid growth and migratory expansion of mid-nineteenth-century pioneer populations carrying the gene. L1649R affects a highly conserved residue in the NC1 domain, which is involved in key inter- and intramolecular interactions, but results in a relatively mild disease phenotype. Renal failure in an L1649R male typically occurs in the 4th or 5th decade and precedes the onset of significant hearing loss by approximately 10 years.