Sexually Antagonistic Selection, Sexual Dimorphism, and the Resolution of Intralocus Sexual Conflict

Males and females share most of their genomes and express many of the same traits, yet the sexes often have markedly different selective optima for these shared traits. This sexually antagonistic (SA) selection generates intralocus sexual conflict that is thought to be resolved through the evolution of sexual dimorphism. However, we currently know little about the prevalence of SA selection, the components of fitness that generate sexual antagonism, or the relationship between sexual dimorphism and current SA selection. We reviewed published studies to address these questions, using 424 selection estimates representing 89 traits from 34 species. Males and females often differed substantially in the direction and magnitude of selection on shared traits, although statistically significant SA selection was relatively uncommon. Sexual selection generated stronger sexual antagonism than fecundity or viability selection, and these individual components of fitness tended to reinforce one another to generate even stronger sexual antagonism for net fitness. Traits exhibiting strong sexual dimorphism exhibited greater SA selection than did weakly dimorphic traits, although this pattern was not significant after we controlled for the inclusion of multiple traits nested within species. Our results suggest that intralocus sexual conflict often may persist despite the evolution of sexual dimorphism

Green Leaf Grocery - Executive Compensation Case Study

The primary purpose of this teaching case is to aid students in understanding how executive compensation plans are utilized to achieve organizational goals and to then construct their own executive compensation plan for the CEO of Greenleaf Grocery, a fictional retail business based on an actual company. Students have the opportunity to create a comprehensive executive compensation plan using salary, bonuses, stock options, benefits, and other compensation tools. Additionally, the case provides the opportunity to discuss the use of both short-term and long-term incentive compensation. The company in this case is poised to undertake an initial public offering of stock and retaining the current CEO is viewed as critical for this next phase. The case affords the class the opportunity to explore ethical issues in executive compensation as well as other aspects of the organization’s overall compensation structure

Evidence for genetic divergence in ribosomal RNA genes in mycobacteria

DNA was isolated from Mycobacterium phlei and from M. smegmatis. Each DNA sample was restricted with endonucleases, the fragments were separated by agarose gel electrophoresis and transferred to nitrocellulose film. Fragments of DNA containing rRNA sequences were identified by means of 125I-labelled rRNA of M. phlei or of M. smegmatis. The distributions of restriction endonuclease sites within the rRNA gene(s) and flanking sequences were found to be characteristic for each of the two species. Hybridizations with heterologous probes indicate that although M. phlei rRNA and M. smegmatis rRNA share regions of sequence homology, they are probably not identical in primary structure. The results suggest that the rRNA genes might prove to be useful taxonomic markers for mycobacteria

Regulatory activity revealed by dynamic correlations in gene expression noise

Gene regulatory interactions are context dependent, active in some cellular states but not in others. Stochastic fluctuations, or 'noise', in gene expression propagate through active, but not inactive, regulatory links^(1,2). Thus, correlations in gene expression noise could provide a noninvasive means to probe the activity states of regulatory links. However, global, 'extrinsic', noise sources generate correlations even without direct regulatory links. Here we show that single-cell time-lapse microscopy, by revealing time lags due to regulation, can discriminate between active regulatory connections and extrinsic noise. We demonstrate this principle mathematically, using stochastic modeling, and experimentally, using simple synthetic gene circuits. We then use this approach to analyze dynamic noise correlations in the galactose metabolism genes of Escherichia coli. We find that the CRP-GalS-GalE feed-forward loop is inactive in standard conditions but can become active in a GalR mutant. These results show how noise can help analyze the context dependence of regulatory interactions in endogenous gene circuits

Natural Selection on Thermal Performance in a Novel Thermal Environment

Tropical ectotherms are thought to be especially vulnerable to climate change because they are adapted to relatively stable temperature regimes, such that even small increases in environmental temperature may lead to large decreases in physiological performance. One way in which tropical organisms may mitigate the detrimental effects of warming is through evolutionary change in thermal physiology. The speed and magnitude of this response depend, in part, on the strength of climate-driven selection. However, many ectotherms use behavioral adjustments to maintain preferred body temperatures in the face of environmental variation. These behaviors may shelter individuals from natural selection, preventing evolutionary adaptation to changing conditions. Here, we mimic the effects of climate change by experimentally transplanting a population of Anolis sagrei lizards to a novel thermal environment. Transplanted lizards experienced warmer and more thermally variable conditions, which resulted in strong directional selection on thermal performance traits. These same traits were not under selection in a reference population studied in a less thermally stressful environment. Our results indicate that climate change can exert strong natural selection on tropical ectotherms, despite their ability to thermoregulate behaviorally. To the extent that thermal performance traits are heritable, populations may be capable of rapid adaptation to anthropogenic warming

High Resolution 8 mm and 1 cm Polarization of IRAS 4A from the VLA Nascent Disk and Multiplicity (VANDAM) Survey

Magnetic fields can regulate disk formation, accretion and jet launching. Until recently, it has been difficult to obtain high resolution observations of the magnetic fields of the youngest protostars in the critical region near the protostar. The VANDAM survey is observing all known protostars in the Perseus Molecular Cloud. Here we present the polarization data of IRAS 4A. We find that with ~ 0.2'' (50 AU) resolution at {\lambda} = 8.1 and 10.3 mm, the inferred magnetic field is consistent with a circular morphology, in marked contrast with the hourglass morphology seen on larger scales. This morphology is consistent with frozen-in field lines that were dragged in by rotating material entering the infall region. The field morphology is reminiscent of rotating circumstellar material near the protostar. This is the first polarization detection of a protostar at these wavelengths. We conclude from our observations that the dust emission is optically thin with {\beta} ~ 1.3, suggesting that mm/cm-sized grains have grown and survived in the short lifetime of the protostar.Comment: Accepted to ApJL. 13 pages, 4 figure

The analysis of lattice and triple lattice experiments in corn varietal tests I Construction and numerical analysis by Gertrude M. Cox and Robert C. Eckhardt II Mathematical theory by W. G. Cochran

Two incomplete block designs, the lattice and triple lattice, are discussed. Their construction, the field plans, experimental results, the statistical analysis and new features of the mathematical theory are included. The two experiments consist of yield tests of 81 double-crosses of corn. They are used to illustrate a new method of analysis in which the inter-block information is recovered. The analysis is presented in such a way that it can be adopted as the standard method of analyzing lattice and triple lattice experiments. The recovery of inter-block information and the reduction of block size from 81 to 9 plots per block resulted in a notable increase in precision when compared with the randomized complete block designs. The gain was 85 percent for the lattice experiment and 73 percent for the triple lattice experiment

Trust in Private and Common Property Experiments

We report the results from a series of experiments designed to investigate behavior in two settings that are frequently posited in the policy literature as generating different outcomes: private property and common property. The experimental settings closely parallel earlier experimental studies of the investment or trust game. The primary research question relates to the effect of the initial allocation of property rights on the level of trust that subjects will extend to others with whom they are linked. We find that assigning the initial endowments as common property of each of N pairs of a first mover and second mover leads to marginally greater cooperation or trust than when the initial endowments are fully owned by the two individual movers as their, respective, private property. Subjectsâ?? decisions are also shown to be correlated with attitudes toward trust and fairness that are measured in post-experiment questionnaires.