Comparing Alternative Output-Gap Estimators: A Monte Carlo Approach

The author evaluates the ability of a variety of output-gap estimators to accurately measure the output gap in a model economy. A small estimated model of the Canadian economy is used to generate artificial data. Using output and inflation data generated by this model, the author uses each output-gap estimation methodology to construct an estimate of the true output gap. He then evaluates the methodologies by comparing their respective estimates of the output gap with the true gap. The estimators are evaluated on the basis of correlations between the actual and estimated output gap, as well as the root-mean-squared estimation error. The author also varies the properties of potential output and the output gap in the data-generating process to test the robustness of his results. His findings indicate that an estimator that combines the Hodrick-Prescott filter with a Blanchard-Quah structural vector autoregression (SVAR) yields an estimate that is accurate compared with competing methods at the end-of-sample. He also finds that the performance of the SVAR relative to that of other methodologies is quite robust to violations in the identifying assumptions of the SVAR.Business fluctuations and cycles; Econometric and statistical methods; Potential output

Extracting Information from the Business Outlook Survey: A Principal-Component Approach

This article reviews recent work that uses principal-component analysis to extract information common to indicators from the Bank of Canada’s Business Outlook Survey (BOS). The authors use correlation analysis and an out-of-sample forecasting exercise to assess and compare the information content of the principal component with that of responses to key individual survey questions on growth in real gross domestic product and in real business investment. Results suggest that summarizing the common movements among BOS indicators may provide useful information for forecasting near-term growth in business investment. For growth in real gross domestic product, however, the survey’s balance of opinion on future sales growth appears to be more informative.

Parallel changes in gut microbiome composition and function in parallel local adaptation and speciation

The processes of local adaptation and ecological speciation are often strongly shaped by biotic interactions such as competition and predation. One of the strongest lines of evidence that biotic interactions drive evolution comes from repeated divergence of lineages in association with repeated changes in the community of interacting species. Yet, relatively little is known about the repeatability of changes in gut microbial communities and their role in adaptation and divergence of host populations in nature. Here we utilize three cases of rapid, parallel adaptation and speciation in freshwater threespine stickleback to test for parallel changes in associated gut microbiomes. We find that features of the gut microbial communities have shifted repeatedly in the same direction in association with parallel divergence and speciation of stickleback hosts. These results suggest that changes to gut microbiomes can occur rapidly and predictably in conjunction with host evolution, and that host-microbe interactions might play an important role in host adaptation and diversification

Evolutionary ecology of opsin gene sequence, expression and repertoire.

Linking molecular evolution to biological function is a long-standing challenge in evolutionary biology. Some of the best examples of this involve opsins, the genes that encode the molecular basis of light reception. In this issue of Molecular Ecology, three studies examine opsin gene sequence, expression and repertoire to determine how natural selection has shaped the visual system. First, Escobar-Camacho et al. () use opsin repertoire and expression in three Amazonian cichlid species to show that a shift in sensitivity towards longer wavelengths is coincident with the long-wavelength-dominated Amazon basin. Second, Stieb et al. () explore opsin sequence and expression in reef-dwelling damselfish and find that UV- and long-wavelength vision are both important, but likely for different ecological functions. Lastly, Suvorov et al. () study an expansive opsin repertoire in the insect order Odonata and find evidence that copy number expansion is consistent with the permanent heterozygote model of gene duplication. Together these studies emphasize the utility of opsin genes for studying both the local adaptation of sensory systems and, more generally, gene family evolution

A Structural Small Open-Economy Model for Canada

The authors develop a small open-economy dynamic stochastic general-equilibrium (DSGE) model in an attempt to understand the dynamic relationships in Canadian macroeconomic data. The model differs from most recent DSGE models in two key ways. First, for prices and wages, the authors use the time-dependent staggered contracting model of Dotsey, King, and Wolman (1999) and Wolman (1999), rather than the Calvo (1983) specification. Second, to model investment, the authors adopt Edge's (2000a, b) framework of time-to-build with ex-post inflexibilities. The model's parameters are chosen to minimize the distance between the structural model's impulse responses to interest rate, demand (consumption), and exchange rate shocks and those from an estimated vector autoregression (VAR). The majority of the model's theoretical impulse responses fall within the 5 and 95 per cent confidence intervals generated by the VAR.Business fluctuations and cycles; Economic models; Inflation and prices

Genetics of adaptation: Experimental test of a biotic mechanism driving divergence in traits and genes.

The genes underlying adaptations are becoming known, yet the causes of selection on genes-a key step in the study of the genetics of adaptation-remains uncertain. We address this issue experimentally in a threespine stickleback species pair showing exaggerated divergence in bony defensive armor in association with competition-driven character displacement. We used semi-natural ponds to test the role of a native predator in causing divergent evolution of armor and two known underlying genes. Predator presence/absence altered selection on dorsal spines and allele frequencies at the Msx2a gene across a generation. Evolutionary trajectories of alleles at a second gene, Pitx1, and the pelvic spine trait it controls, were more variable. Our experiment demonstrates how manipulation of putative selective agents helps to identify causes of evolutionary divergence at key genes, rule out phenotypic plasticity as a sole determinant of phenotypic differences, and eliminate reliance on fitness surrogates. Divergence of predation regimes in sympatric stickleback is associated with coevolution in response to resource competition, implying a cascade of biotic interactions driving species divergence. We suggest that as divergence proceeds, an increasing number of biotic interactions generate divergent selection, causing more evolution in turn. In this way, biotic adaptation perpetuates species divergence through time during adaptive radiation in an expanding number of traits and genes

Rolf Bochhuth's interpretation of history, and its effect on the content, form and reception of his dramatic work

This thesis attempts to account for the diversity and occasional inconsistency that characterise Rolf Hochhuth's theoretical essays and plays. Initially, the nature and extent of several philosophical, historical and literary influences upon Hochhuth are discussed in order to build up a broad picture of the author's concept of historical events and the individual's role in them. A selection of plays is presented in the light of these findings. They include the much-discussed earlier plays, directly concerned with history and its presentation, and later works within which Hochhuth speculates about a possible future. Parallels are drawn between the arguments presented in these plays and those ideas which he has elucidated in his theoretical work. Hochhuth's fluctuating and eclectic choice of dramatic structure is then examined as a possible consequence of the diversity of these same ideas. A new area of interest is seen to emerge in Hochhuth's writing during the 1970s in a series of plays about women. His theories - and questions - concerning history are again viewed as the motivation for these works, and their reflection in the contentand structure of Lysistrate und die Hato and Judith illustrated in detail. The thesis establishes the uncertain and speculative nature of Hochhuth's attitude to history. In the context of a brief discussion of the reception of his plays, therefore, a final chapter indicates the dangers of adopting a narrow ideological perspective when approaching Hochhuth's work. This may have the effect of highlighting the author's failings, and produce a negative overall evaluation. A broader perspective which does justice to the diverse arguments and questions explored in his writing would seem to offer a more fruitful approach to Rolf Hochhuth