Deep mtDNA divergences indicate cryptic species in a fig-pollinating wasp

Background: Figs and fig-pollinating wasps are obligate mutualists that have coevolved for ca 90 million years. They have radiated together, but do not show strict cospeciation. In particular, it is now clear that many fig species host two wasp species, so there is more wasp speciation than fig speciation. However, little is known about how fig wasps speciate. Results: We studied variation in 71 fig-pollinating wasps from across the large geographic range of Ficus rubiginosa in Australia. All wasps sampled belong to one morphological species (Pleistodontes imperialis), but we found four deep mtDNA clades that differed from each other by 9–17% nucleotides. As these genetic distances exceed those normally found within species and overlap those (10–26%) found between morphologically distinct Pleistodontes species, they strongly suggest cryptic fig wasp species. mtDNA clade diversity declines from all four present in Northern Queensland to just one in Sydney, near the southern range limit. However, at most sites multiple clades coexist and can be found in the same tree or even the same fig fruit and there is no evidence for parallel sub-division of the host fig species. Both mtDNA data and sequences from two nuclear genes support the monophyly of the "P. imperialis complex" relative to other Pleistodontes species, suggesting that fig wasp divergence has occurred without any host plant shift. Wasps in clade 3 were infected by a single strain (W1) of Wolbachia bacteria, while those in other clades carried a double infection (W2+W3) of two other strains. Conclusion: Our study indicates that cryptic fig-pollinating wasp species have developed on a single host plant species, without the involvement of host plant shifts, or parallel host plant divergence. Despite extensive evidence for coevolution between figs and fig wasps, wasp speciation may not always be linked strongly with fig speciation

On a class of linearizable Monge-Amp\`ere equations

Monge-Amp\`ere equations of the form, $u_{xx}u_{yy}-u_{xy}^2=F(u,u_x,u_y)$ arise in many areas of fluid and solid mechanics. Here it is shown that in the special case $F=u_y^4f(u, u_x/u_y)$, where $f$ denotes an arbitrary function, the Monge-Amp\`ere equation can be linearized by using a sequence of Amp\`ere, point, Legendre and rotation transformations. This linearization is a generalization of three examples from finite elasticity, involving plane strain and plane stress deformations of the incompressible perfectly elastic Varga material and also relates to a previous linearization of this equation due to Khabirov [7]

Herbicide Resistance in Ryegrass: Stochastic Evaluation of Management Strategies

Annual Ryegrass is a significant weed in cereal production in Western Australia. Herbicide resistance is increasing and is a major concern to producers. Long-term, field scale trials are being conducted on a number of sites in the state. The apparent costs and benefits of different management strategies are dependent on seasonal conditions and markets for inputs and products. This paper presents the results of a simulation model of alternative strategies under a wide range of historic conditions. A conceptual framework for selecting an optimal strategy is explored.Crop Production/Industries, Farm Management,

Measuring Employee Turnover in Australian Pig Production

Limited availability of competent and motivated staff has been repeatedly cited as one of the major constraints on pig production in Australia. Whilst a considerable effort is put into training staff (Western Australia boasts the most advanced training facility in South-East Asia), practically nothing is known about the rates of employee turnover. Based on a postal survey and case studies of high and low turnover piggeries, this paper provides the first objective measures of staff turnover in the pig industry and explores possible explanatory factors. Measurement of turnover can provide managers with a benchmark to assess their own performance. This study also revealed shortcomings in the standard Separation Method used by the Australian Bureau of Statistics when it is applied to relatively small businesses. Alternative measures were calculated and are discussed.Farm Management,

Farming in the "New Economy" : An Australian Perspective

Barriers to trade between countries have reduced through the general Agreement on Tariffs and Trade (GATT) and the World Trade Organisation (WTO). The nature of trade between businesses is also changing dramatically through developments in Information Technology but also due to adoption of quality assurance and new approaches to supply chain management. The impacts of this "New Economy" vary around the world. This paper considers the implications of these developments for Australian farmers. Whilst these changes can be regarded as generally advantageous to Australian farmers, they may be disadvantaged in some areas because of the relatively small size of the Australian farming sector, its geographical dispersion, the advent of a range of new technologies and the structure of agribusinesses. The potential changes to the nature of farming and farm management skills are discussed.Farm Management,

Online revenue model adoption in the media sector: in-depth results from an exploratory study in the Netherlands

Especially for companies in the media sector such as publishers, the Internet has created new strategic and commercial opportunities. However, many companies in the media sector are struggling with how to adapt their business and revenue model for doing profitable business online. This exploratory study goes into the success factors and the level of adoption of online revenue models by media sector companies. We use Chaffey (2002) in determining online revenue models in which we included Osterwalder’s (2001) four ‘pillars’ of business models. These four pillars cover the twelve critical success factors for e-businesses as identified by Sung (2004). This theoretical framework was used for in-depth interviews with 20 senior managers within the media sector in the Netherlands. From this, it appeared that advertising is the most used online revenue model, with targeting advertising, lead generation and a combination of content and customer profiles as most promising. Ease of use is distinguished by all senior managers as success factor. Still, in order to be successful, all factors should be applied, and this appears not to be the case. Organizations in the media sector need to invest in technical and organizational expertise by hiring the right employees with the right knowledge. Emphasis on target advertising and lead generation are most promising. A combination of content and customer profiles is a focus-point for the near future

Subnanometer Translation of Microelectromechanical Systems Measured by Discrete Fourier Analysis of CCD Images

Abstract—In-plane linear displacements of microelectromechanical systems are measured with subnanometer accuracy by observing the periodic micropatterns with a charge-coupled device camera attached to an optical microscope. The translation of the microstructure is retrieved from the video by phase-shift computation using discrete Fourier transform analysis. This approach is validated through measurements on silicon devices featuring steep-sided periodic microstructures. The results are consistent with the electrical readout of a bulk micromachined capacitive sensor, demonstrating the suitability of this technique for both calibration and sensing. Using a vibration isolation table, a standard deviation of σ = 0.13 nm could be achieved, enabling a measurement resolution of 0.5 nm (4σ) and a subpixel resolution better than 1/100 pixel. [2010-0170

Error, bias, and long-branch attraction in data for two chloroplast photosystem genes in seed plants

Sequences of two chloroplast photosystem genes, psaA and psbB, together comprising about 3,500 bp, were obtained for all five major groups of extant seed plants and several outgroups among other vascular plants. Strongly supported, but significantly conflicting, phylogenetic signals were obtained in parsimony analyses from partitions of the data into first and second codon positions versus third positions. In the former, both genes agreed on a monophyletic gymnosperms, with Gnetales closely related to certain conifers. In the latter, Gnetales are inferred to be the sister group of all other seed plants, with gymnosperms paraphyletic. None of the data supported the modern ‘‘anthophyte hypothesis,’’ which places Gnetales as the sister group of flowering plants. A series of simulation studies were undertaken to examine the error rate for parsimony inference. Three kinds of errors were examined: random error, systematic bias (both properties of finite data sets), and statistical inconsistency owing to long-branch attraction (an asymptotic property). Parsimony reconstructions were extremely biased for third-position data for psbB. Regardless of the true underlying tree, a tree in which Gnetales are sister to all other seed plants was likely to be reconstructed for these data. None of the combinations of genes or partitions permits the anthophyte tree to be reconstructed with high probability. Simulations of progressively larger data sets indicate the existence of long-branch attraction (statistical inconsistency) for third-position psbB data if either the anthophyte tree or the gymnosperm tree is correct. This is also true for the anthophyte tree using either psaA third positions or psbB first and second positions. A factor contributing to bias and inconsistency is extremely short branches at the base of the seed plant radiation, coupled with extremely high rates in Gnetales and nonseed plant outgroups. M. J. Sanderson,* M. F. Wojciechowski,*† J.-M. Hu,* T. Sher Khan,* and S. G. Brad

Bound states in two spatial dimensions in the non-central case

We derive a bound on the total number of negative energy bound states in a potential in two spatial dimensions by using an adaptation of the Schwinger method to derive the Birman-Schwinger bound in three dimensions. Specifically, counting the number of bound states in a potential gV for g=1 is replaced by counting the number of g_i's for which zero energy bound states exist, and then the kernel of the integral equation for the zero-energy wave functon is symmetrized. One of the keys of the solution is the replacement of an inhomogeneous integral equation by a homogeneous integral equation.Comment: Work supported in part by the U.S. Department of Energy under Grant No. DE-FG02-84-ER4015