Hitchhiking and Recombination in Birds: Evidence from Mhc-linked and Unlinked Loci in Red-winged Blackbirds (Agelaius phoeniceus)

Hitchhiking phenomena and genetic recombination have important consequences for a variety of fields for which birds are model species, yet we know virtually nothing about naturally occurring rates of recombination or the extent of linkage disequilibrium in birds. We took advantage of a previously sequenced cosmid clone from Red-winged Blackbirds (Agelaius phoeniceus) bearing a highly polymorphic Mhc class II gene, Agph-DABI, to measure the extent of linkage disequilibrium across similar to40 kb of genomic DNA and to determine whether non-coding nucleotide diversity was elevated as a result of physical proximity to a target of balancing. selection. Application of coalescent theory predicts that the hitchhiking effect is enhanced by the larger effective population size of blackbirds compared with humans, despite the presumably higher rates of recombination in birds. We surveyed sequence polymorphism at three Mhc-linked loci occurring 1.5-40 kb away from Agph-DABI and found that nucleotide diversity was indistinguishable from that found at three presumably unlinked, non-coding introns (beta-actin intron 2, beta-fibrinogen intron 7 and rhodopsin intron 2). Linkage disequilibrium as measured by Lewontin's D' was found only across a few hundred base pairs within any given locus, and was not detectable among any Mhc-linked loci. Estimated rates of the per site recombination rate p derived from three different analytical methods suggest that the amounts of recombination in blackbirds are up to two orders of magnitude higher than in humans, a discrepancy that cannot be explained entirely by the higher effective population size of blackbirds relative to humans. In addition, the ratio of the number of estimated recombination events per mutation frequently exceeds 1, as in Drosophila, again much higher than estimates in humans. Although the confidence limits of the blackbird estimates themselves span an order of magnitude, these data suggest that in blackbirds the hitchhiking effect for this region is negligible and may imply that the per site per individual recombination rate is high, resembling those of Drosophila more than those of humans.Organismic and Evolutionary Biolog

The Effects of Uncertainty on Market Structure: The South Dakota Slaughter Cattle Market

In terms of population and income, South Dakota is a small, rural state relative to the rest of the nation. South Dakota\u27s 1992 Gross State Product (GSP) was roughly 12 billion dollars, which implies South Dakota contributes .2% toward U.S. Gross Domestic Product (GDP). The agricultural sector of the South Dakota economy contributed approximately 10% to GSP in 1992. The beef industry is the largest agricultural subsector in the state. In 1992, it generated 1.3 billion dollars in marketing revenue and produced approximately 41% of agriculture\u27s contribution to GSP. The importance of the beef industry to the South Dakota\u27s economy merits an examination of the market structure which has evolved for the selling of slaughter cattle in South Dakota. This essay examines the effect of relaxing the assumptions of the competitive model on firm behavior and market structure. The perfectly competitive market model is based on the following assumptions: 1) a large number of buyers and sellers who are price takers in the market; 2) freedom of firm entry and exit; 3) all participants in the market have complete information on all relevant market characteristics; 4) buyer preference and cost structures are identical and the same is true for sellers; and 5) firms (beef producers) produce a homogeneous product

Production Uncertainty and Factor Price Disparity in the Slaughter Cattle Market: Theory and Evidence

The theoretical analysis of competitive firm behavior under economic uncertainty has been explored in the areas of input and output price uncertainty in the papers by Baron (1970), Sandmo (1971), Batra and Ullah (1974), and Blair (1974) among others. The issue of the competitive firm facing production uncertainty generated by input quality variability was addressed in a paper by Ratti and Ullah (1976). Other papers applied their approach to specific areas, such as, wage discrimination being explained by labor quality variability.1 A simple model of a competitive firm confronting production uncertainty, generated by the variability in the flow of factor service (input), is presented below. The authors believe that the assumptions of the model developed in this paper provides a realistic description of the short run behavior of firms engaged in meat packing operations in the upper Midwest and purchasing cattle in the slaughter cattle market. This paper follows the approach used to analyze production uncertainty developed by Ratti and Ullah. The purpose of our study is to analyze firm behavior when it must purchase its input (steers) in an auction market under two different informational conditions. This in essence, creates two submarkets for the purchasing of the input. The firm has either complete information or incomplete information concerning the contribution to production of the input it is purchasing.2 Incomplete information implies that there is uncertainty over the contribution to production of the input when purchased. The term contribution to production , will be denoted CTP throughout the rest of the paper

RISK AND MARKET PARTICIPANT BEHAVIOR IN THE U.S. SLAUGHTER-CATTLE MARKET

Incomplete information generates uncertainty for market participants in the slaughter-cattle market. Buyer and seller behavior in the presence of that uncertainty is examined. Statistically significant risk premiums are charged by packers when buying slaughter cattle on either a live- or dressed-weight basis compared to buying on a grade-and-yield basis. Pratt-Arrow risk-aversion coefficients are calculated for buyers and these remain constant over all marketing methods. Sellers market cattle under all three marketing methods, suggesting producersÂ’' attitudes toward risk (risk-aversion coefficients) vary.Risk and Uncertainty,

Polarization proximity effect in isolator crystal pairs

We experimentally studied the polarization dynamics (orientation and ellipticity) of near infrared light transmitted through magnetooptic Yttrium Iron Garnet crystal pairs using a modified balanced detection scheme. When the pair separation is in the sub-millimeter range, we observed a proximity effect in which the saturation field is reduced by up to 20%. 1D magnetostatic calculations suggest that the proximity effect originates from magnetostatic interactions between the dipole moments of the isolator crystals. This substantial reduction of the saturation field is potentially useful for the realization of low-power integrated magneto-optical devices.Comment: submitted to Optics Letter

PRECISION AGRICULTURE, WHOLE FIELD FARMING AND IRRIGATION PRACTICES: A PRODUCTION RISK ANALYSIS

One of the potential management practices of precision agriculture (PA) is the capability of varying input application rate across a field. A potential benefit of that practice is the reduction in yield variability. Temporal reduction in yield variability can also be achieved through irrigation practices. Combining both practices should lead to a reduction of the yield risk faced by the farmer. In this study, variable rate application of nutrients will include to nitrogen, potassium and phosphate. Mathematical programming techniques will be used in a standard E-V framework to analyze the ability of PA and/or irrigation to reduce production risk.Risk and Uncertainty,

Risk and Market Participant Behavior in the U.S. Slaughter Cattle Market

Incomplete and varying degrees of information on product quality creates risk in a market transaction. Numerous researchers have documented that market participants will react differently in the presence of risk depending upon their attitudes toward risk. Many of these studies have classified agricultural market participants according to the Arrow-Pratt risk aversion coefficient into three general categories of risk averse, risk neutral, or risk preferring (Raskin and Cochran, Wilson and Eidman, King and Robinson) and have found individuals in all three categories. The U.S. slaughter cattle market is currently operating in an environment where the amount of information available on product quality varies depending upon the marketing method used. There are presently three main cash marketing methods. available to producers in the US: (1) live weight; (2) dressed weight (in-the-beef); and (3) dressed weight and grade (grade and yield). The information differential generates uncertainty (risk). It follows that the degree of risk associated with each of these marketing methods varies with the amount of information available on product quality. In a recent paper by Feuz, Fausti, and Wagner it was reported that producers\u27 profits differed between the live, in-the-beef, and grade and yield marketing methods for slaughter cattle. They indicated that profits on average were highest with grade and yield marketing and lowest with live wejght marketing. They also found that the variance in producer profits (risk) were greatest for grade and yield and smallest for live weight marketing. The objectives of this research are to determine: 1) what effect the risk associated with incomplete information across marketing methods is having on the market price for slaughter cattle; and 2) what effect product quality uncertainty is having on buyer and seller behavior. The accomplishment of these objectives should · provide additional insight into the U.S. slaughter cattle market and be particularly valuable to those looking to modify the existing marketing methods or create new value based marketing methods

An Empirical Analysis of the Efficiency of Four Alternative Marketing Methods for Slaughter Cattle

Four alternative marketing methods for slaughter cattle were analyzed and empirically examined for pricing efficiency. Profits per head were found to be significantly different under the various marketing methods. Greater price discrimination occurred as carcass information increased. Increased price discrimination led to greater dispersion of profit from one marketing method to another. Different marketing methods appeared to send different production signals to producers. The desires of the consumer for less fat and a high quality product did not appear to be reaching the producers in the form of profit incentives under the most widely used marketing method

An Economic Feasibility Assessment of Autonomous Field Machinery in Grain Crop Production

A multi-faceted whole farm planning model is developed to compare conventional and autonomous machinery for grain crop production under various benefit, farm size, suitable field day risk aversion, and grain price scenarios. Results suggest that autonomous machinery can be an economically viable alternative to conventional manned machinery if the establishment of intelligent controls is cost effective. An increase in net returns of 24% over operating with conventional machinery is found when including both input savings and a yield increase due to reduced compaction. This study also identifies the break-even investment price for intelligent controls for the safe and reliable commercialization of autonomous machinery. Results indicate that the break-even investment price is highly variable depending on the financial benefits resulting from the deployment of autonomous machinery, farm size, suitable field day risk aversion, and grain prices. The maximum break-even investment price for intelligent, autonomous controls is nearly US$500 000 for the median days suitable for fieldwork when including both input savings and a yield increase due to reduced compaction