Empirical examination of the individual‐level personality‐based theory of self‐management failure

The individual‐level personality‐based theory of self‐management failure posits that personality predisposes individuals to self‐defeating behavior that, in turn, leads to self‐management failure (Renn, Allen, Fedor, & Davis, 2005). To provide a partial test of the theory, a model is hypothesized that operationalized personality with neuroticism and conscientiousness of the Big Five personality dimensions; self‐defeating behavior with inability to delay gratification, procrastination, and emotional self‐absorption; and self‐management with personal goal setting, monitoring, and operating. The model was tested using data collected from 286 working employees and structural equations analysis. Results supported nine of 11 theory‐derived hypotheses. As hypothesized, high neuroticism was associated with improper personal goal setting, monitoring, and operating; and emotional self‐absorption and procrastination accounted for the relationship between high neuroticism and ineffective self‐management. In addition, low conscientiousness was associated with inferior self‐management practices, and inability to delay gratification and procrastination partially explained the relationship between low conscientiousness and poor self‐management. The findings provide new insight into how high neuroticism and low conscientiousness may contribute to self‐management failure. Theoretical and practical implications of the study are discussed. Copyright © 2009 John Wiley & Sons, Ltd.     

Sex-specific conditional mating preferences in a cichlid fish: implications for sexual conflict

Conditional mating strategies enable individuals to modulate their mating behaviour depending on ‘individual status’ to maximise fitness. Theory predicts that variation in individual quality can lead to differences in mating preferences. However, empirical evidence is scarce particular in terms of variation in male and female strategies. Here, we experimentally investigated quality-dependent variation in mating preferences concerning reliable quality indicators in Pelvicachromis taeniatus, a colourful cichlid fish with mutual mate choice and ornamentation. Males as well as females were artificially manipulated in phenotypic quality by different feeding regimes. Ornamentation was connected to individual quality in both sexes. Males and females showed conditional mating strategies in different directions. Males showed prudent choice by preferring females of similar quality. In contrast to males, low-quality females preferred highly ornamented males, whereas high-quality females showed neither preferences for high- nor for low-quality males. The results suggest that individuals aim for specific benefits depending on individual quality. Furthermore, the conflicting conditional mating preferences of males and females might lead to sexual conflict, implicating a highly dynamical mating system that evolves even in absence of environmental changes.     

Applying habitat and population-density models to land-cover time series to inform IUCN Red List assessments

The IUCN (International Union for Conservation of Nature) Red List categories and criteria are the most widely used framework for assessing the relative extinction risk of species. The criteria are based on quantitative thresholds relating to the size, trends, and structure of species’ distributions and populations. However, data on these parameters are sparse and uncertain for many species and unavailable for others, potentially leading to their misclassification or classification as data deficient. We devised an approach that combines data on land-cover change, species-specific habitat preferences, population abundance, and dispersal distance to estimate key parameters (extent of occurrence, maximum area of occupancy, population size and trend, and degree of fragmentation) and hence predict IUCN Red List categories for species. We applied our approach to nonpelagic birds and terrestrial mammals globally (∼15,000 species). The predicted categories were fairly consistent with published IUCN Red List assessments, but more optimistic overall. We predicted 4.2% of species (467 birds and 143 mammals) to be more threatened than currently assessed and 20.2% of data deficient species (10 birds and 114 mammals) to be at risk of extinction. Incorporating the habitat fragmentation subcriterion reduced these predictions 1.5–2.3% and 6.4–14.9% (depending on the quantitative definition of fragmentation) for threatened and data deficient species, respectively, highlighting the need for improved guidance for IUCN Red List assessors on the application of this aspect of the IUCN Red List criteria. Our approach complements traditional methods of estimating parameters for IUCN Red List assessments. Furthermore, it readily provides an early-warning system to identify species potentially warranting changes in their extinction-risk category based on periodic updates of land-cover information. Given our method relies on optimistic assumptions about species distribution and abundance, all species predicted to be more at risk than currently evaluated should be prioritized for reassessment.     

An example of the prisoner's dilemma in biochemistry

Two strains of microorganisms that both use sugar as energy resource, but which may choose between two different pathways of ATP production, are studied from a game-theory point of view. We consider these pathways as distinct strategies to which we assign payoffs that are proportional to the expected steady-state number of individuals sustainable on the basis of these strategies. In a certain parameter range, we find that the payoffs fulfil the conditions for the prisoner's dilemma. Therefore, cooperative behaviour is unlikely to occur, unless additional factors intervene. In fact, the yeast Saccharomyces cerevisiae uses a competitive strategy by fermenting sugars even under aerobic conditions, thus wasting its own resource. The simple quantifiable structure of the model should enable access to an experimentally determined payoff matrix.     

Scent of a queen—cuticular hydrocarbons specific for female reproductives in lower termites

In social insects, it is assumed that signals of the queen inform nestmates about her reproductive status. Thus, workers forego their own reproduction if the queen signals high fertility. In hemimetabolous termites, little is known about reproductive inhibition, but evidence exists for a royal-pair control. Workers of lower termites exhibit a high developmental flexibility and are potentially able to become reproductives, but the presence of a fertile reproductive restrains them from reaching sexual maturity. The nature of this control, however, remains unknown. Here, we report on qualitative differences in cuticular hydrocarbon profiles between queens and workers of the basal drywood termite Cryptotermes secundus. Queens were characterized by a shift to long-chained and branched hydrocarbons. Most remarkably, similar chemical patterns are regarded as fertility cues of reproductives in social Hymenoptera. This might suggest that both groups of social insects convergently evolved similar chemical signatures. The present study provides deeper insights into how termites might have socially exploited these signatures from sexual communication in their cockroach-like ancestor. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Two pathways ensuring social harmony

Reproductive division of labour is a characteristic trait of social insects. The dominant reproductive individual, often the queen, uses chemical communication and/or behaviour to maintain her social status. Queens of many social insects communicate their fertility status via cuticle-bound substances. As these substances usually possess a low volatility, their range in queen–worker communication is potentially limited. Here, we investigate the range and impact of behavioural and chemical queen signals on workers of the ant Temnothorax longispinosus. We compared the behaviour and ovary development of workers subjected to three different treatments: workers with direct chemical and physical contact to the queen, those solely under the influence of volatile queen substances and those entirely separated from the queen. In addition to short-ranged queen signals preventing ovary development in workers, we discovered a novel secondary pathway influencing worker behaviour. Workers with no physical contact to the queen, but exposed to volatile substances, started to develop their ovaries, but did not change their behaviour compared to workers in direct contact to the queen. In contrast, workers in queen-separated groups showed both increased ovary development and aggressive dominance interactions. We conclude that T. longispinosus queens influence worker ovary development and behaviour via two independent signals, both ensuring social harmony within the colony.     

Soil lead (Pb) in residential transects through Lubbock,Texas: a preliminary assessment

Residential lead (Pb) contamination, resulting from decades-long use of leaded gasoline and lead-based paint, is likely to be present in soils in most urban areas. A screening level sampling effort demonstrated that Lubbock, Texas, USA, like other cities of its age and size, has areas of elevated soil Pb. This effort was based on soil sampling performed on residential, commercial and thoroughfare properties. The focus of this study was to investigate that component of soil contamination due to combustion of leaded gasoline. Soils were collected from the 1–2 cm surface layer from street-side property borders, well away from buildings that might lead to soil contamination from leaded paint chips. All samples were analyzed for Pb after a 1 M HNO₃ mild extraction to determine the amount of bioavailable Pb. Two of three transects through the city demonstrated significant trends of decreasing Pb concentrations with distance from the city center, paralleling a decrease in developed property age. Peak soil Pb concentrations outside city development was 4.9 ± 0.6 mg/kg while the median concentration for the city was 35.4 mg/kg. Peak soil Pb concentrations in the city center ranged from 90.0 to 174.0 mg/kg and decreased exponentially to 6.0–9.0 mg/kg at the furthest terminus of the residential transects.     

Archetypical patterns and trajectories of land systems in Europe

Regional Environmental Change - Assessments of land-system change have dominantly focused on conversions among broad land-use categories, whereas intensity changes within these categories have...