Changes In Selection Patterns Research Articles

Design and effectiveness of start-up subsidies: Evidence from a policy reform in Germany

While a growing body of literature finds positive impacts of Start-Up Subsidies (SUS) on labor market outcomes of participants, little is known about how the design of these programs shapes their effectiveness and hence how to improve policy. As experimental variation in program design is unavailable, we exploit the 2011 reform of the current German SUS program for the unemployed which strengthened caseworkers’ discretionary power, increased entry requirements and reduced monetary support. We estimate the impact of the reform on the program’s effectiveness using samples of participants and non-participants from before and after the reform. To control for time-constant unobserved heterogeneity as well as differential selection patterns based on observable characteristics over time, we combine Difference-in-Differences with inverse probability weighting using covariate balancing propensity scores. Holding participants’ observed characteristics as well as macroeconomic conditions constant, the results suggest that the reform was successful in raising employment effects on average. As these findings may be contaminated by changes in selection patterns based on unobserved characteristics, we assess our results using simulation-based sensitivity analyses and find that our estimates are highly robust to changes in unobserved characteristics. Hence, the reform most likely had a positive impact on the effectiveness of the program, suggesting that increasing entry requirements and reducing support increased the program’s impacts while reducing the cost per participant.

Design and Effectiveness of Start-Up Subsidies: Evidence from a Policy Reform in Germany

While a growing body of literature finds positive impacts of Start-Up Subsidies (SUS) on labor market outcomes of participants, little is known about how the design of these programs shapes their effectiveness and hence how to improve policy. As experimental variation in program design is unavailable, we exploit the 2011 reform of the current German SUS program for the unemployed which strengthened case-workers’ discretionary power, increased entry requirements and reduced monetary support. We estimate the impact of the reform on the program’s effectiveness using samples of participants and non-participants from before and after the reform. To control for time-constant unobserved heterogeneity as well as differential selection patterns based on observable characteristics over time, we combine Difference-in-Differences with inverse probability weighting using covariate balancing propensity scores. Holding participants’ observed characteristics as well as macroeconomic conditions constant, the results suggest that the reform was successful in raising employment effects on average. As these findings may be contaminated by changes in selection patterns based on unobserved characteristics, we assess our results using simulation-based sensitivity analyses and find that our estimates are highly robust to changes in unobserved characteristics. Hence, the reform most likely had a positive impact on the effectiveness of the program, suggesting that increasing entry requirements and reducing support in-creased the program’s impacts while reducing the cost per participant.

The changing nature of gender selection into employment over the great recession

SUMMARY The Great Recession has strongly influenced employment patterns across skill and gender groups in EU countries. We analyse how these changes in workforce composition might distort comparisons of conventional measures of gender wage gaps via non-random selection of workers into EU labour markets. We document that male selection (traditionally disregarded) has become positive during the recession, particularly in Southern Europe. As for female selection (traditionally positive), our findings are twofold. Following an increase in the labour-force participation of less-skilled women, due to an added-worker effect, these biases declined in some countries where new female entrants were able to find jobs, whereas they went up in other countries which suffered large female employment losses. Finally, we document that most of these changes in selection patterns were reversed during the subsequent recovery phase, confirming their cyclical nature.

The Organelle Genomes in the Photosynthetic Red Algal Parasite Pterocladiophila hemisphaerica (Florideophyceae, Rhodophyta) Have Elevated Substitution Rates and Extreme Gene Loss in the Plastid Genome.

Comparative organelle genome studies of parasites can highlight genetic changes that occur during the transition from a free-living to a parasitic state. Our study focuses on a poorly studied group of red algal parasites, which are often closely related to their red algal hosts and from which they presumably evolved. Most of these parasites are pigmented and some show photosynthetic capacity. Here, we assembled and annotated the complete organelle genomes of the photosynthetic red algal parasite, Pterocladiophila hemisphaerica. The plastid genome is the smallest known red algal plastid genome at 68,701bp. The plastid genome has many genes missing, including all photosynthesis-related genes. In contrast, the mitochondrial genome is similar in architecture to that of other free-living red algae. Both organelle genomes show elevated mutation rates and significant changes in patterns of selection, measured as dN/dS ratios. This caused phylogenetic analyses, even of multiple aligned proteins, to be unresolved or give contradictory relationships. Full plastid datasets interfered by selected best gene evolution models showed the supported relationship of P.hemisphaerica within the Ceramiales, but the parasite was grouped with support as sister to the Gracilariales when interfered under the GHOST model. Nuclear rDNA showed a supported grouping of the parasite within a clade containing several red algal orders including the Gelidiales. This photosynthetic parasite, which is unable to photosynthesize with its own plastid due to the total loss of all photosynthesis genes, raises intriguing questions on parasite-host organelle genome capabilities and interactions.

An alternative reference point in the context of ecosystem-based fisheries management: maximum sustainable dead biomass

Abstract Under the 2013 Reform of the European Union's Common Fisheries Policy (CFP), fisheries management aims to ensure that, within a reasonable time frame, the exploitation of marine biological resources restores and maintains populations of harvested stocks above levels that can produce the maximum sustainable yield (MSY). The CFP also calls for the implementation of an ecosystem-based approach to fisheries management (EBFM). In this paper, we present the concept of maximum sustainable dead biomass (MSDB) and its associated management reference points for fishing mortality and spawning-stock biomass as alternatives to those associated with MSY. The concept of MSDB is illustrated by a dynamic pool production model of a virtual fish stock which takes into account variations in natural mortality (M), fishing mortality (F), and exploitation pattern. Our approach implies a compensatory mechanism whereby survivors may benefit from compensatory density dependence and is implemented through progressive substitution of M with F for varying rates of total mortality (Z). We demonstrate that the reference points for fishing mortality and spawning-stock biomass associated with MSDB are less sensitive to increasing compensation of M with F than those associated with MSY and more sensitive to changes in selection pattern. MSDB-based reference points, which are consistent with maximum stock productivity, are also associated with lower fishing mortality rates and higher stock biomasses than their MSY-based counterparts. Given that selection pattern can be influenced through fishery input measures (e.g. technical gear measures, decisions on areas, and/or times of fishing), whereas variations of M in response to F are not controllable (indeed poorly understood), that the results of many fish stock assessments are imprecise, that maximum stock productivity corresponds to MSDB and that MSY-based reference points may best be considered as limits, we propose that MSDB-based reference points provide a more appropriate basis for management under an EBFM.

Short-term responses of wolf feeding habits to changes of wild and domestic ungulate abundance in Northern Italy

Long-term changes of wolf feeding habits have been recorded in several parts of its European range and were related to the increase of wild ungulate populations. An increased use of wild prey often is linked to a decrease of predation on livestock, and consequently it can reduce wolf–human conflict and make for easier predator conservation. We analysed wolf diet from scats collected from 2007 to 2012 in a 927.3-km2 area of the Northern Apennines (Northern Italy) to compare the present diet to that recorded in the late 1980s when the area was colonised by wolves, and to examine short-term changes of wolf feeding habits together with annual and seasonal variations of wild and domestic ungulate selection, possibly related to the increase of wild ungulate abundance. We calculated the availability proportions of wild ungulate species from the presence signs recorded on itineraries and those of livestock species from the data on farms of veterinary services. We identified 17 kinds of prey, pooled into six categories, of which wild ungulates (70%) and livestock (20%) were the most important. During the study period, we observed a reduction in the diet breadth of wolves, to a greater use of wild ungulates, depending on the increase in the availability of wild prey species. Significant seasonal variations were observed in the trophic habits of the wolf, but generally there was a wide use of wild ungulates, especially wild boars. Livestock was mainly used in summer, which corresponds to the period of greatest presence of domestic ungulates on the pastures. Considering the study period, a fast response of wolf feeding habits to the increase of wild ungulate species resulted, together with changes in selection patterns. The change in diet towards a greater use of wild ungulates is an important step in the recovery and conservation of the wolf.

Extreme climatic events in relation to global change and their impact on life histories

Abstract Extreme weather conditions occur at an increasing rate as evidenced by higher frequency of hurricanes and more extreme precipitation and temperature anomalies. Such extreme environmental conditions will have important implications for all living organisms through greater frequency of reproductive failure and reduced adult survival. We review examples of reproductive failure and reduced survival related to extreme weather conditions. Phenotypic plasticity may not be sufficient to allow adaptation to extreme weather for many animals. Theory predicts reduced reproductive effort as a response to increased stochasticity. We predict that patterns of natural selection will change towards truncation selection as environmental conditions become more extreme. Such changes in patterns of selection may facilitate adaptation to extreme events. However, effects of selection on reproductive effort are difficult to detect. We present a number of predictions for the effects of extreme weather conditions in need of empirical tests. Finally, we suggest a number of empirical reviews that could improve our ability to judge the effects of extreme environmental conditions on life history.

A change in nucleotide selectivity pattern of porphyrin derivatives after immobilization on gold nanoparticles

Two porphyrin-quaternized brucine salts 1 and 2 were immobilized on 3-mercaptopropanoic acid derivatized gold nanoparticles. The porphyrin modified nanoparticles were purified and characterized by a variety of techniques including electron microscopy and absorption spectroscopy in the UV–vis range. Interactions of nucleotides with 1 and 2 in solution and after immobilization of 1 and 2 on the surface of the nanoparticles were studied. A change in the selectivity pattern towards nucleotides as an effect of the porphyrin derivative immobilization is demonstrated.

RESPONSES OF CAVITY-NESTING BIRDS TO CHANGES IN AVAILABLE HABITAT REVEAL UNDERLYING DETERMINANTS OF NEST SELECTION

Despite an abundance of studies describing nest selection in cavity-nesting birds, few account for the variation in habitat availability across the geographic range of a species and through time. Changes in the frequency of disturbances such as fires, timber harvests, and insect outbreaks can dramatically alter habitat. Responses by cavity-nesting birds to these changes provide an opportunity to evaluate underlying determinants of nest selection. We compared nest site attributes to available resources for 3 species of cavity-nesting birds: the Pileated Woodpecker (Dryocopus pileatus), Williamson's Sapsucker (Sphyrapicus thyroideus), and Black-backed Woodpecker (Picoides arcticus). Data collected in 2003–2004 were compared to data collected in the 1970s in the same study area to identify changes in patterns of selection. Due to severe insect outbreaks, available resources differed greatly between the 2 time periods. In studies separated by 30 y, Pileated Woodpeckers and Black-backed Woodpeckers exhibited remarkable consistency in patterns of nest site selection. Both species still selected Ponderosa Pine (Pinus ponderosa) snags preferentially for nesting despite their decline in availability. Williamson's Sapsuckers were less selective and nested in the most abundant snag species during both time periods. Selection for factors such as tree size and degree of decay remained consistent regardless of differences in habitat availability for the 3 species. By identifying these general patterns of nest site selection, our conclusions are applicable to a wider variety of habitat conditions.

Density‐related changes in selection pattern for major histocompatibility complex genes in fluctuating populations of voles

Host-pathogen interactions are of particular interest in studies of the interplay between population dynamics and natural selection. The major histocompatibility complex (MHC) genes of demographically fluctuating species are highly suitable markers for such studies, because they are involved in initiating the immune response against pathogens and display a high level of adaptive genetic variation. We investigated whether two MHC class II genes (DQA1, DRB) were subjected to contemporary selection during increases in the density of fossorial water vole (Arvicola terrestris) populations, by comparing the neutral genetic structure of seven populations with that estimated from MHC genes. Tests for heterozygosity excess indicated that DQA1 was subject to intense balancing selection. No such selection operated on neutral markers. This pattern of selection became more marked with increasing abundance. In the low-abundance phase, when populations were geographically isolated, both overall differentiation and isolation-by-distance were more marked for MHC genes than for neutral markers. Model-based simulations identified DQA1 as an outlier (i.e. under selection) in a single population, suggesting the action of local selection in fragmented populations. The differences between MHC and neutral markers gradually disappeared with increasing effective migration between sites. In the high-abundance year, DQA1 displayed significantly lower levels of overall differentiation than the neutral markers. This gene therefore displayed stronger homogenization than observed under drift and migration alone. The observed signs of selection were much weaker for DRB. Spatial and temporal fluctuations in parasite pressure and locus-specific selection are probably the most plausible mechanisms underlying the observed changes in selection pattern during the demographic cycle.

Have changes in selectivity masked recruitment declines in crustacean trap fisheries?

In the Tasmanian rock lobster assessment model, as in many other assessment models, selectivity is treated as a fixed effect. The actual size composition in the population is estimated by dividing the survey catch in each size class by the size-specific selectivity. Recently, it has been found that larger lobsters tend to inhibit smaller lobsters from entering traps. We suggest that, as larger lobsters are removed from the population by harvesting, the number of smaller lobsters in the catch increases because they become more catchable. To determine the effect of a change in selectivity pattern on our perception of population composition, we applied selectivity curves that accounted for the effects of a change in size composition to sampling data from a population of lobsters that had seen a substantial decline in large legal-sized lobsters due to harvesting over the last 35 years. The results suggest that recent recruitment is lower than the recruitment that occurred in the 1960s, but this is masked in the unadjusted sampling data by changes in selectivity. This could contribute to masking of a stock–recruitment relationship. If this is a common phenomenon in crustacean trap fisheries, the assessment approaches now in use may be more risk prone than previously realised.

Have changes in selectivity masked recruitment declines in crustacean trap fisheries?

In the Tasmanian rock lobster assessment model, as in many other assessment models, selectivity is treated as a fixed effect. The actual size composition in the population is estimated by dividing the survey catch in each size class by the size-specific selectivity. Recently, it has been found that larger lobsters tend to inhibit smaller lobsters from entering traps. We suggest that, as larger lobsters are removed from the population by harvesting, the number of smaller lobsters in the catch increases because they become more catchable. To determine the effect of a change in selectivity pattern on our perception of population composition, we applied selectivity curves that accounted for the effects of a change in size composition to sampling data from a population of lobsters that had seen a substantial decline in large legal-sized lobsters due to harvesting over the last 35 years. The results suggest that recent recruitment is lower than the recruitment that occurred in the 1960s, but this is masked in the unadjusted sampling data by changes in selectivity. This could contribute to masking of a stock–recruitment relationship. If this is a common phenomenon in crustacean trap fisheries, the assessment approaches now in use may be more risk prone than previously realised.

E‐books: the University of Texas experience, part 2

This article follows‐up on an earlier Library Hi Tech article on the e‐book program at the University of Texas. It notes changes in usage that have occurred with the addition of e‐book catalog records in the library online catalog, and changes in selection patterns as librarians have gained more experience with the e‐book. It also surveys the current digital information environment, notes the increasing commodification of information, details the e‐book efforts of the Association of American Publishers and examines potential future e‐book directions.