Re-Evaluating Hypertragulid Diversity in the John Day Basin, Oregon, USA

Despite their relative abundance, members of the family Hypertragulidae (Artiodactyla, Mammalia) have proved a conundrum regarding species diversity in the Turtle Cove Member (Oligocene) of the John Day Formation, located in central and eastern Oregon. Three species and two separate genera are described in the area, but previous research lacks statistical support for this level of variation. We use coefficients of variation (V) on measurements of dentition and astragali of hypertragulid specimens designated Hypertragulus hesperius, Hypertragulus minutus, and Nanotragulus planiceps as a metric for determining whether there were multiple species present in the population. Asymptotic and modified signed-likelihood ratio V equality tests show that V values of anterior-posterior molar length and transverse molar width vary significantly when comparing single species of modern ecological analogs (Muntiacus muntjak, Muntiacus reevesi, and Tragulus javanicus) to groupings of a combined population. However, the V equality tests on dental and postcranial measurements yield almost no significant results when comparing variation in the extinct John Day hypertragulids to an extant population comprised of a single species. Similar comparisons between astragali measurements of hypertragulids and T. javanicus express no significant difference in the level of variation from the combined population to a modern single species. The low level of variation in the hypertragulids and the lack of differentiation between dental characters of individuals does not statistically support the hypothesis that there were multiple species present in the population, suggesting either that cryptic species may be present but impossible to identify without soft tissue remains, or there may have been taxonomic over-splitting of a single hypertragulid species in the John Day region

Microtomography of an enigmatic fossil egg clutch from the Oligocene John Day Formation, Oregon, USA, reveals an exquisitely preserved 29-million-year-old fossil grasshopper ootheca

Eggs are one of the least understood life stages of insects, and are poorly represented in the fossil record. Using microtomography, we studied an enigmatic fossil egg clutch of a presumed entomological affinity from the Oligocene Turtle Cove Member, John Day Formation, from the National Park Service-administered lands of John Day Fossil Beds National Monument, Oregon. A highly organized egg mass comprising a large clutch size of approximately 50 slightly curved ellipsoidal eggs arranged radially in several planes is preserved, enclosed in a disc-shaped layer of cemented and compacted soil particles. Based on the morphology of the overall structure and the eggs, we conclude that the specimen represents a fossilized underground ootheca of the grasshoppers and locusts (Orthoptera: Caelifera), also known as an egg pod. This likely represents the oldest and the first unambiguous fossil evidence of a grasshopper egg pod. We describe Subterroothecichnus radialis igen. et isp. nov. and Curvellipsoentomoolithus laddi oogen. et oosp. nov., representing the egg pod and the eggs, respectively. We advocate for adopting ootaxonomy in studying fossil eggs of entomological affinities, as widely practiced with fossil amniotic eggs. An additional 26 individual and clustered C. laddi collected throughout the A–H subunits of the Turtle Cove Member suggest the stable presence of grasshoppers in the Turtle Cove fauna, and we discuss the paleoecological implications. Oothecae have convergently evolved several times in several insect groups; this ovipositional strategy likely contributed to the fossilization of this lesser-known ontogenetic stage, enriching our understanding of past insect life

Experimental Analysis of a Plume Dispersion Around Obstacles

Abstract Nowadays, transport and deposition of aerosol particles (PM 2.5 , PM 10 , TSP) caused by industrial plants, environmental applications and transports, are of great concern to public health. Despite the establishment by the European Union of emission standards (European directive 2008/50/CE e.g) to control the limits of particulates in the air, the emissions by industrial plants are still not accurately monitored. In particular, the interaction between plume dispersion and obstacles, such as buildings, is not currently well studied. A lot of theoretical researches were carried out in this field with a lack of experimental data comparison. This paper focuses on a laboratory work made to better explain the interaction of a continuous plume released from a point source and various obstacles. First of all a vertical pipe was reproduced, a continuous aerosol emitter was characterized in terms of a specified and controlled mass flow and the ratio between smoke emission and the total suspended particulates thanks to use of the certified gravimetric calculation of PM 10 . The experimental campaigns were conducted by means of a wind tunnel all the data collected were validated. The characterization of plume was made by the use of several sensors and calculation of velocity in several points of the field. Moreover, the plume dispersion was studied also by using digital image analysis. It was then investigated downwind the influence of obstacles of various shapes and distances from source in terms of aerosol concentration in several points

Theoretical and Experimental Study of Gaussian Plume Model in Small Scale System

Abstract Atmospheric dispersion pollution modelling is of great and actual concern in the scientific international community. Many dispersion models have been developed and used to estimate the downwind ambient concentration of air pollutants from sources such as industrial plants, vehicular traffic or accidental chemical release. Among them, Gaussian model is perhaps the most commonly used model type. It is often used to predict the dispersion of air pollution plumes originated from ground-level or elevated sources. In this research an experimental campaign was carried out in the wind tunnel of the Industrial Engineering Department of University of Catania. It was tested an emission plume of particulate matters and the concentrations of PM 10 were evaluated in several points downwind beyond the emitter. Both the wind velocity and PM 10 mass flow were varied in order to test the differences in terms of PM10 concentrations in the sampling points. A Gaussian plume mathematical model was developed according the boundaries conditions of the experimental campaign. The results of the model were compared with experimental ones in order to identify the limits and the advantages of this model in such a small scale system

Paleobiology of a Large Mammal Community From the Late Pleistocene of Sonora, Mexico

A paleontological deposit near San Clemente de Térapa represents one of the very few Rancholabrean North American Land Mammal Age sites within Sonora, Mexico. During that time, grasslands were common, and the climate included cooler and drier summers and wetter winters than currently experienced in northern Mexico. Here, we demonstrate restructuring in the mammalian community associated with environmental change over the past 40,000 years at Térapa. The fossil community has a similar number of carnivores and herbivores whereas the modern community consists mostly of carnivores. There was also a 97% decrease in mean body size (from 289 kg to 9 kg) because of the loss of megafauna. We further provide an updated review of ungulates and carnivores, recognizing two distinct morphotypes of Equus, including E. scotti and a slighter species; as well as Platygonus compressus; Camelops hesternus; Canis dirus; and Lynx rufus; and the first regional records of Palaeolama mirifica, Procyon lotor, and Smilodon cf. S. fatalis. The Térapa mammals presented here provide a more comprehensive understanding of the faunal community restructuring that occurred in northern Mexico from the late Pleistocene to present day, indicating further potential biodiversity loss with continued warming and drying of the region

Genome wide association mapping of grain arsenic, copper, molybdenum and zinc in rice (Oryza sativa L.) grown at four international field sites

Peer reviewedPublisher PD

Genetic Architecture of Aluminum Tolerance in Rice (Oryza sativa) Determined through Genome-Wide Association Analysis and QTL Mapping

Aluminum (Al) toxicity is a primary limitation to crop productivity on acid soils, and rice has been demonstrated to be significantly more Al tolerant than other cereal crops. However, the mechanisms of rice Al tolerance are largely unknown, and no genes underlying natural variation have been reported. We screened 383 diverse rice accessions, conducted a genome-wide association (GWA) study, and conducted QTL mapping in two bi-parental populations using three estimates of Al tolerance based on root growth. Subpopulation structure explained 57% of the phenotypic variation, and the mean Al tolerance in Japonica was twice that of Indica. Forty-eight regions associated with Al tolerance were identified by GWA analysis, most of which were subpopulation-specific. Four of these regions co-localized with a priori candidate genes, and two highly significant regions co-localized with previously identified QTLs. Three regions corresponding to induced Al-sensitive rice mutants (ART1, STAR2, Nrat1) were identified through bi-parental QTL mapping or GWA to be involved in natural variation for Al tolerance. Haplotype analysis around the Nrat1 gene identified susceptible and tolerant haplotypes explaining 40% of the Al tolerance variation within the aus subpopulation, and sequence analysis of Nrat1 identified a trio of non-synonymous mutations predictive of Al sensitivity in our diversity panel. GWA analysis discovered more phenotype–genotype associations and provided higher resolution, but QTL mapping identified critical rare and/or subpopulation-specific alleles not detected by GWA analysis. Mapping using Indica/Japonica populations identified QTLs associated with transgressive variation where alleles from a susceptible aus or indica parent enhanced Al tolerance in a tolerant Japonica background. This work supports the hypothesis that selectively introgressing alleles across subpopulations is an efficient approach for trait enhancement in plant breeding programs and demonstrates the fundamental importance of subpopulation in interpreting and manipulating the genetics of complex traits in rice

Genome-wide association mapping identifies a new arsenate reductase enzyme critical for limiting arsenic accumulation in plants

Inorganic arsenic is a carcinogen, and its ingestion through foods such as rice presents a significant risk to human health. Plants chemically reduce arsenate to arsenite. Using genome-wide association (GWA) mapping of loci controlling natural variation in arsenic accumulation in Arabidopsis thaliana allowed us to identify the arsenate reductase required for this reduction, which we named High Arsenic Content 1 (HAC1). Complementation verified the identity of HAC1, and expression in Escherichia coli lacking a functional arsenate reductase confirmed the arsenate reductase activity of HAC1. The HAC1 protein accumulates in the epidermis, the outer cell layer of the root, and also in the pericycle cells surrounding the central vascular tissue. Plants lacking HAC1 lose their ability to efflux arsenite from roots, leading to both increased transport of arsenic into the central vascular tissue and on into the shoot. HAC1 therefore functions to reduce arsenate to arsenite in the outer cell layer of the root, facilitating efflux of arsenic as arsenite back into the soil to limit both its accumulation in the root and transport to the shoot. Arsenate reduction by HAC1 in the pericycle may play a role in limiting arsenic loading into the xylem. Loss of HAC1-encoded arsenic reduction leads to a significant increase in arsenic accumulation in shoots, causing an increased sensitivity to arsenate toxicity. We also confirmed the previous observation that the ACR2 arsenate reductase in A. thaliana plays no detectable role in arsenic metabolism. Furthermore, ACR2 does not interact epistatically with HAC1, since arsenic metabolism in the acr2 hac1 double mutant is disrupted in an identical manner to that described for the hac1 single mutant. Our identification of HAC1 and its associated natural variation provides an important new resource for the development of low arsenic-containing food such as rice

Genome-wide association mapping reveals a rich genetic architecture of complex traits in Oryza sativa

Asian rice, Oryza sativa is a cultivated, inbreeding species that feeds over half of the world's population. Understanding the genetic basis of diverse physiological, developmental, and morphological traits provides the basis for improving yield, quality and sustainability of rice. Here we show the results of a genome-wide association study based on genotyping 44,100 SNP variants across 413 diverse accessions of O. sativa collected from 82 countries that were systematically phenotyped for 34 traits. Using cross-population-based mapping strategies, we identified dozens of common variants influencing numerous complex traits. Significant heterogeneity was observed in the genetic architecture associated with subpopulation structure and response to environment. This work establishes an open-source translational research platform for genome-wide association studies in rice that directly links molecular variation in genes and metabolic pathways with the germplasm resources needed to accelerate varietal development and crop improvement