Polygenic contribution to the relationship of loneliness and social isolation with schizophrenia

Previous research suggests an association of loneliness and social isolation (LNL-ISO) with schizophrenia. Here, we demonstrate a LNL-ISO polygenic score contribution to schizophrenia risk in an independent case-control sample (N = 3,488). We then subset schizophrenia predisposing variation based on its effect on LNL-ISO. We find that genetic variation with concordant effects in both phenotypes shows significant SNP-based heritability enrichment, higher polygenic contribution in females, and positive covariance with mental disorders such as depression, anxiety, attention-deficit hyperactivity disorder, alcohol dependence, and autism. Conversely, genetic variation with discordant effects only contributes to schizophrenia risk in males and is negatively correlated with those disorders. Mendelian randomization analyses demonstrate a plausible bi-directional causal relationship between LNL-ISO and schizophrenia, with a greater effect of LNL-ISO liability on schizophrenia than vice versa. These results illustrate the genetic footprint of LNL-ISO on schizophrenia.

Pre- and post-copulatory traits working in concert: sexual dichromatism in passerines is associated with sperm morphology

Passerine birds produce costly traits under intense sexual selection, including elaborate sexually dichromatic plumage and sperm morphologies, to compete for fertilizations. Plumage and sperm traits vary markedly among species, but it is unknown if this reflects a trade-off between pre- and post-copulatory investment under strong sexual selection producing negative trait covariance, or variation in the strength of sexual selection among species producing positive covariance. Using phylogenetic regression, we analysed datasets describing plumage and sperm morphological traits for 278 passerine species. We found a significant positive relationship between sperm midpiece length and male plumage elaboration and sexual dichromatism. We did not find a relationship between plumage elaboration and testes mass. Our results do not support a trade-off between plumage and sperm traits, but may be indicative of variance among species in the strength of sexual selection to produce both brightly coloured plumage and costly sperm traits.

More than the sum of the parts: annual partitioning within spatial guilds underpins community regulation

To withstand the pressures of a rapidly changing world, resilient ecosystems should exhibit compensatory dynamics, including uncorrelated temporal shifts in population sizes. The observation that diversity is maintained through time in many systems is evidence that communities are indeed regulated and stabilized, yet empirical observations suggest that positive covariance in species abundances is widespread. This paradox could be resolved if communities are composed of a number of ecologically relevant sub-units in which the members compete for resources, but whose abundances fluctuate independently. Such modular organization could explain community regulation, even when the community as a whole appears synchronized. To test this hypothesis, we quantified temporal synchronicity in annual population abundances within spatial guilds in an estuarine fish assemblage that has been monitored for 36 years. We detected independent fluctuations in annual abundances within guilds. By contrast, the assemblage as a whole exhibited temporal synchronicity—an outcome linked to the dynamics of guild dominants, which were synchronized with each other. These findings underline the importance of modularity in explaining community regulation and highlight the need to protect assemblage composition and structure as well as species richness.

From Mentoring to Career Satisfaction: The Roles of Distributive Justice and Organizational Commitment

A mentor-mentee relationship is a productive partnership on both sides. Mentoring has been repeatedly shown to positively influence several work-related outcomes in an organization. Therefore, the present study explored how mentoring, distributive justice, organizational commitment and career satisfaction are related to each other in order to reveal the mentoring effects both at individual and organizational levels. The study included a sample of 280 participants. SPSS 22.0 and AMOS 22.00 software programs were used to perform the statistical analyses of the study data. The results revealed that mentor role and distributional justice have positive effects on organizational commitment, while organizational commitment positively affects career satisfaction. There was also a positive covariance between mentor role and distributive justice. The findings are discussed from the perspective of both management literature and organizational implications.

The Price-Trading Volume Relationship in the Brazilian Stock Market, the Impact of Stock Lending and a Role for Technical Analysis

We examine the relationship between price and volume in the Brazilian stock market. It tests the “V-shaped relationship” developed by Karpoff (1987), identified in several empirical papers for the U.S. market. This is expressed by positive covariance between a stock’s market turnover and the absolute value of that stock’s price change in the same period. This would contradict the implication from weak market efficiency that current price would impound all information. We analyze daily data for 47 stocks covering the period from January 04, 2010 to June 28, 2013. The results indicate that the V-shaped relationship is significant.

Coupled micromorphological and stable isotope analysis of Quaternary calcrete development

Pedogenic calcretes are widespread in arid and semi-arid regions. Using calcrete profiles from four river terraces of the Rio Alias in southeast Spain, this study explores the potential of using detailed micromorphological and stable isotopic analysis to more fully understand the impacts of Quaternary environmental change on calcrete development. The four profiles increase in carbonate complexity with progressive age, reflecting calcretisation over multiple glacial–interglacial cycles since MIS 9 (c. 300 ka). Calcrete profiles contain a mixture of Alpha (non-biogenic) and Beta (biogenic) microfabrics. Alpha fabrics have higher δ13C and δ18O values. The profiles contain a range of crystal textures, but there is little difference between the δ13C and δ18O values of spar, microspar, and micrite cements. Strong positive covariance between δ13C and δ18O suggests that both isotopes are responding to the same environmental parameter, which is inferred to be relative aridity. The study reveals that the detailed co-analysis of calcrete micromorphology and stable isotope signatures can allow patterns of calcrete formation to be placed into a wider palaeoclimatic context. This demonstrates the potential of this technique to more reliably constrain the palaeoenvironmental significance of secondary carbonates in dryland settings where other proxy records may be poorly preserved.

Flaws in evolutionary theory and interpretation

We make three points. First, even if Finlay et al.'s proposed developmental mechanisms hold, there remains great scope for selection on specific brain structures. Second, the positive covariance among the size of brain structures provides far less support for the proposed developmental mechanisms than Finlay et al. acknowledge. Third, even if the proposed mechanisms are the primary size determinants for most brain structures, these structures should not be considered “spandrels.”

Positive associations among riparian bird species correspond to elevational changes in plant communities

Bird count data were used to characterize patterns of abundance and distribution among 20 bird species occupying streamside habitats of the central Rocky Mountains. Cluster analysis classified bird assemblages from 10 study plots into three elevational zones that varied in bird species diversity. Monotonic declines in total bird densities over the elevational gradient corresponded to spatial fluctuations in population levels of a few numerically dominant species. Of 190 correlations in counts of species pairs, 48 were significant, a much greater proportion than that expected by chance. Only 12 of the 48 associations were negative, suggesting that current competition may be less important than other processes in structuring these communities. Five suites of the positively associating species were detected using cluster, correlational, and variance analyses. Aggregated species responded to habitat ecotones by simultaneously increasing or decreasing in abundance. Group composition was dependent on patterns of species distribution among elevational zones, and on whether species were specialists or generalists in habitat use. Abundances of 19 species were related to five habitat gradients created by principal components analysis of habitat structure. A reasonable explanation for positive covariance in bird abundance is that species responded similarly to limiting resources that were associated with elevational zones.