Competition among eucalyptus trees depends on genetic variation and resource supply

Genetic variation and environmental heterogeneity fundamentally shape the interactions between plants of the same species. According to the resource partitioning hypothesis, competition between neighbors intensifies as their similarity increases. Such competition may change in response to increasing supplies of limiting resources. We tested the resource partitioning hypothesis in stands of genetically identical (clone-origin) and genetically diverse (seed-origin) Eucalyptus trees with different water and nutrient supplies, using individual-based tree growth models. We found that genetic variation greatly reduced competitive interactions between neighboring trees, supporting the resource partitioning hypothesis. The importance of genetic variation for Eucalyptus growth patterns depended strongly on local stand structure and focal tree size. This suggests that spatial and temporal variation in the strength of species interactions leads to reversals in the growth rank of seed-origin and clone-origin trees. This study is one of the first to experimentally test the resource partitioning hypothesis for intergenotypic vs. intragenotypic interactions in trees. We provide evidence that variation at the level of genes, and not just species, is functionally important for driving individual and community-level processes in forested ecosystems.     

Evaluation of biotechnological processes to obtain ethanol from recycled paper sludge

Journal of Material Cycles and Waste Management - Finding innovative solutions to manage waste and to expand the production of biofuels are some of the current challenges. Pulp and paper sectors,...     

Protective effect of gamma-oryzanol against manganese-induced toxicity in Drosophila melanogaster

Environmental Science and Pollution Research - Manganese (Mn) is an essential element that, in excess, seems to be involved in the development of different neurodegenerative conditions....     

Chemometric tools applied to optimize a fast solid-phase microextraction method for analysis of polycyclic aromatic hydrocarbons in produced water

Environmental Science and Pollution Research - Chemometric tools are powerful strategies to efficiently optimize many processes. These tools were employed to optimize a fast-solid phase...     

Assessment and sources of nonaromatic hydrocarbons in surface sediments of three harbors in Santa Catarina State, Brazil

Nonaromatic hydrocarbons and geochemical parameters from 17 sediment?Cwater interface samples were used to assess sources of organic matter in three harbors, located in Santa Catarina State, southern Brazil. The evaluation was based on the molar C/N/P ratios, abundance of resolved nonaromatic hydrocarbons (3.0?C25.9 ??g g^???1), unresolved complex mixture, and two indexes: the carbon preference index (CPI) and the low molecular weight to high molecular weight ratio. The results indicate that the organic matter is predominantly of terrestrial origin (C/N > 10 and CPI > 2). Variations in the total organic carbon from 0.43 to 2.98 mmol g^???1 and total phosphorus from 82.4 to 464.3 ??g g^???1 showed no clear correlation with the silt and clay fractions of the sediments possibly due to anthropogenic input. In contrast to the low level of contamination based on the acyclic hydrocarbon distribution, the results obtained from a series of geologically stable hopanes and steranes reveal the presence of less degradable petroleum derivatives.     

Low genetic differentiation between isolated populations of the colonial ascidian Symplegma rubra Monniot, C. 1972

Pelagic larvae are highly important for maintaining the gene flow among populations of sessile marine invertebrates. Colonial ascidians consist, exclusively, of brooding species, with lecithotrophic larvae that have a limited dispersal. As a result, there is a marked differentiation among populations. In this work, we used allozyme electrophoresis to access the genetic variation in four populations of Symplegma rubra, a colonial ascidian frequently found in the intertidal zone of Southeastern Brazilian coast. High variability was found at three of the four sites sampled, the exception being Praia Grande in the State of Rio de Janeiro. At this site, there was a great preponderance of clones, which possibly reflected the enclosed nature of the location and its low water circulation that reduce the dispersal capabilities of these animals. S. rubra did not conform to expectations for random mating (Hardy–Weinberg equilibrium): there was a deficit of heterozygotes that was more related to the small population size than to inbreeding processes, since F _is analysis per locus revealed a deficiency of heterozygotes at only one locus—MDH*. The greatest variation in allele frequency was found for GPI-2*. Analyses of genetic variability revealed moderate differentiation among the populations (F _ST=0.051), which was unexpected for a species with a low dispersal capability. Rafting, a frequently underestimated means of dispersal, may be the main mode of gene flow in this species over large areas, since colonies of S. rubra are frequently seen growing on drift material and there is no evidence that the larva survive for a long time in the plankton.     

Uncommon formation of two antiparallel sperm bundles per cyst in tenebrionid beetles (Coleoptera)

Several species of Tenebrionidae are stored-grain pests. Since they belong to a specious family, the systematics of these beetles is still in doubt. In insects, spermatogenesis and the spermatozoa exhibit great diversity, and are therefore commonly used in phylogenetic and taxonomic analyses. During the spermatogenetic process in these organisms, the cells originating from a single spermatogonium develop synchronically in groups referred to as cysts. At the end of this process, there is usually only one sperm bundle per cyst, with all the cells in the same orientation. This paper details the spermiogenesis of the tenebrionid beetles Tenebrio molitor, Zophobas confusa, Tribolium castaneum and Palembus dermestoides using whole mount and histological sections of the cysts. In these species, spermatogenesis is similar to that which occurs in most insects. However, during spermiogenesis, the nuclei of the spermatids migrate to two opposite regions at the periphery of the cyst, leading to the uncommon formation of two bundles of spermatozoa per cyst. This feature is possibly an apomorphy for Tenebrionidae.     

What can the Allium cepa test say about pesticide safety? A review

Environmental Science and Pollution Research - The increasing use of pesticides has caused global concerns about the toxic effects and adverse consequences of pesticides on humans and the...     

Remarkable sunlight-driven photocatalytic performance of Ag-doped ZnO nanoparticles prepared by green synthesis for degradation of emerging pollutants in water

Environmental Science and Pollution Research - In this work, Ag-doped ZnO nanoparticles (NPs) were synthesized by a simple green method using a toxic agent-free route for photocatalytic purposes,...     

Encapsulation of Nerol Oil in Polycaprolactone Polymer and Stability Evaluation

Journal of Polymers and the Environment - The objective of this study was to obtain and characterize Nerol essential oil encapsulated in PCL. The miniemulsion and solvent evaporation method was...