Phylogeographic Triangulation: Using Predator-Prey-Parasite Interactions to Infer Population History from Partial Genetic Information

Phylogeographic studies, which infer population history and dispersal movements from intra-specific spatial genetic variation, require expensive and time-consuming analyses that are not always feasible, especially in the case of rare or endangered species. On the other hand, comparative phylogeography of species involved in close biotic interactions may show congruent patterns depending on the specificity of the relationship. Consequently, the phylogeography of a parasite that needs two hosts to complete its life cycle should reflect population history traits of both hosts. Population movements evidenced by the parasite’s phylogeography that are not reflected in the phylogeography of one of these hosts may thus be attributed to the other host. Using the wild rabbit (Oryctolagus cuniculus) and a parasitic tapeworm (Taenia pisiformis) as an example, we propose comparing the phylogeography of easily available organisms such as game species and their specific heteroxenous parasites to infer population movements of definitive host/predator species, independently of performing genetic analyses on the latter. This may be an interesting approach for indirectly studying the history of species whose phylogeography is difficult to analyse directly

An update of the Verbenaceae genera and species numbers

Background and aims. The last comprehensive study that estimated the number of Verbenaceae genera and species was published in 2004, and included 34 genera and around 1200 species. Since then, several publications based on morphology and/or molecular data have proposed important changes within the family. Due to the lack of updated literature to cite when referring to the number of Verbenaceae taxa, a review of these estimates is necessary. Key results and conclusion. We present a detailed list of genera currently accepted in Verbenaceae with the number of species contained in each and compare our numbers with the previous estimate. In addition, we indicate the geographic distribution and the most recent important taxonomic or phylogenetic works for each genus. Our compilation shows that Verbenaceae have 32 genera and 800 species currently accepted. This work provides up-to-date numbers and brings a holistic view of the family.Fil: Cardoso, Pedro Henrique. Universidade Federal do Rio de Janeiro; BrasilFil: O'Leary, Nataly Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; ArgentinaFil: Olmstead, Richard G.. University of Washington; Estados UnidosFil: Moroni, Pablo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; ArgentinaFil: Thode, Verônica. Universidade Federal do Rio Grande do Sul; Brasi

The isotopic composition of normal krypton and xenon

Recently a mass-spectrometer investigation of the isotopes of krypton and xenon resulting from the fission of uranium-235 by thermal neutrons was reported.(1) This investigation was carried out with a 180°-deflection Nier-type mass spectrometer.(2

Time-dependent model for vertical-cavity surface-emitting laser

Two models have been developed to simulate a vertical-cavity surface-emitting laser (VCSEL). The first model is a two-dimensional time-dependent solution of Maxwell`s equations, with frequency-independent bulk dielectric and absorption coefficients. These bulk coefficients depend upon the material, lattice temperature, and carrier concentration. This field model is coupled with a frequency-dependent gain model that describes the quantum well regions in the time domain. Treatment of frequency-dependent media in a finite-difference time-domain code is computationally intensive. On the other hand, because the volume of the active region is small relative to the volume of the distributed laser cavity, the computational overhead is reasonable. A semi-empirical transport model is used to describe the bulk transport, which drives the quantum well transport. In addition, the semi-empirical model provides a spatial distribution for the lattice temperature and carrier concentrations. The second model is a three-dimensional solution of Maxwell`s equations. The three-dimensional model can be used for cold-cavity calculations. The two-dimensional code generates the dielectric and absorption coefficients assuming azimuthal symmetry, providing the initial conditions for the three-dimensional calculation

Individual Response to Risk As a Function of Normative Social Pressure: A Pilot Study of Seat Belt Use

The authors attempt to clarify some of the variables that influence whether people act appropriately when a Risk is substantial and subject to individual control. They do so by reporting results of a pilot study of seat belt use. Also, the authors believe their approach to be generalizable to problems such as encouraging people to test for radon, to use condoms to prevent AIDS or to quit smoking

Comparison among five hydrodynamic codes with a diverging-converging nozzle experiment

A realistic open-cycle gas-core nuclear rocket simulation model must be capable of a self-consistent nozzle calculation in conjunction with coupled radiation and neutron transport in three spatial dimensions. As part of the development effort for such a model, five hydrodynamic codes were used to compare with a converging-diverging nozzle experiment. The codes used in the comparison are CHAD, FLUENT, KIVA2, RAMPANT, and VNAP2. Solution accuracy as a function of mesh size is important because, in the near term, a practical three-dimensional simulation model will require rather coarse zoning across the nozzle throat. In the study, four different grids were considered. (1) coarse, radially uniform grid, (2) coarse, radially nonuniform grid, (3) fine, radially uniform grid, and (4) fine, radially nonuniform grid. The study involves code verification, not prediction. In other words, the authors know the solution they want to match, so they can change methods and/or modify an algorithm to best match this class of problem. In this context, it was necessary to use the higher-order methods in both FLUENT and RAMPANT. In addition, KIVA2 required a modification that allows significantly more accurate solutions for a converging-diverging nozzle. From a predictive point of view, code accuracy with no tuning is an important result. The most accurate codes on a coarse grid, CHAD and VNAP2, did not require any tuning. Their main comparison among the codes was the radial dependence of the Mach number across the nozzle throat. All five codes yielded a very similar solution with fine, radially uniform and radially nonuniform grids. However, the codes yielded significantly different solutions with coarse, radially uniform and radially nonuniform grids. For all the codes, radially nonuniform zoning across the throat significantly increased solution accuracy with a coarse mesh. None of the codes agrees in detail with the weak shock located downstream of the nozzle throat, but all the codes indicated the presence of a weak downstream shock