The Enigma of Soil Animal Species Diversity Revisited: The Role of Small-Scale Heterogeneity

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Childhood socioeconomic position and adult leisure-time physical activity: A systematic review

Regular leisure-time physical activity (LTPA) benefits health and is thought to be less prevalent in lower socioeconomic groups. Evidence suggests that childhood socioeconomic circumstances can impact on adult health and behaviour however, it is unclear if this includes an influence on adult LTPA. This review tested the hypothesis that a lower childhood socioeconomic position (SEP) is associated with less frequent LTPA during adulthood. Studies were located through a systematic search of MEDLINE, Embase, PsycINFO, CINAHL and SPORTDiscus and by searching reference lists. Eligible studies were English-language publications testing the association between any indicator of childhood SEP and an LTPA outcome measured during adulthood. Forty-five papers from 36 studies, most of which were European, were included. In most samples, childhood SEP and LTPA were self-reported in midlife. Twenty-two studies found evidence to support the review’s hypothesis and thirteen studies found no association. Accounting for own adult SEP partly attenuated associations. There was more evidence of an association in British compared with Scandinavian cohorts and in women compared with men. Results did not vary by childhood SEP indicator or age at assessment of LTPA. This review found evidence of an association between less advantaged childhood SEP and less frequent LTPA during adulthood. Understanding how associations vary by gender and place could provide insights into underlying pathways

Health Behaviours, Socioeconomic Status, and Mortality: Further Analyses of the British Whitehall II and the French GAZEL Prospective Cohorts

Background: Differences in morbidity and mortality between socioeconomic groups constitute one of the most consistent findings of epidemiologic research. However, research on social inequalities in health has yet to provide a comprehensive understanding of the mechanisms underlying this association. In recent analysis, we showed health behaviours, assessed longitudinally over the follow-up, to explain a major proportion of the association of socioeconomic status (SES) with mortality in the British Whitehall II study. However, whether health behaviours are equally important mediators of the SES-mortality association in different cultural settings remains unknown. In the present paper, we examine this issue in Whitehall II and another prospective European cohort, the French GAZEL study.Methods and Findings: We included 9,771 participants from the Whitehall II study and 17,760 from the GAZEL study. Over the follow-up (mean 19.5 y in Whitehall II and 16.5 y in GAZEL), health behaviours (smoking, alcohol consumption, diet, and physical activity), were assessed longitudinally. Occupation (in the main analysis), education, and income (supplementary analysis) were the markers of SES. The socioeconomic gradient in smoking was greater (p < 0.001) in Whitehall II (odds ratio [OR] = 3.68, 95% confidence interval [CI] 3.11-4.36) than in GAZEL (OR = 1.33, 95% CI 1.18-1.49); this was also true for unhealthy diet (OR = 7.42, 95% CI 5.19-10.60 in Whitehall II and OR = 1.31, 95% CI 1.15-1.49 in GAZEL, p < 0.001). Socioeconomic differences in mortality were similar in the two cohorts, a hazard ratio of 1.62 (95% CI 1.28-2.05) in Whitehall II and 1.94 in GAZEL (95% CI 1.58-2.39) for lowest versus highest occupational position. Health behaviours attenuated the association of SES with mortality by 75% (95% CI 44%-149%) in Whitehall II but only by 19% (95% CI 13%-29%) in GAZEL. Analysis using education and income yielded similar results.Conclusions: Health behaviours were strong predictors of mortality in both cohorts but their association with SES was remarkably different. Thus, health behaviours are likely to be major contributors of socioeconomic differences in health only in contexts with a marked social characterisation of health behaviours

Changes in the oribatid mite community structure associated with the succession from heather (Calluna vulgaris) moorland to birch (Betula pubescens) woodland

Factors determining the total and relative abundance of oribatid mite communities have been well described. In contrast, the factors that determine species composition and species richness of this fauna are far less understood. We tested the hypothesis that oribatid species richness would increase in the secondary succession from heather moorland to birch woodland. This secondary succession is associated with a change in humus form from mor to mull and a complete change in the composition of the understorey vegetation. However, in contrast to most studies of the response of oribatid mites to secondary succession, the invasion of birch can occur without large-scale physical disturbance of the moorland. Our study examined oribatid communities in three replicates of heather moorland, 49- and 58-year-old birch stands at two sites in the Scottish uplands. There was a clear increase in population density and species richness of the oribatids per unit area, and a change in relative abundance of the species, in the birch compared with the heather moorland. However, multivariate analyses indicated that only a few species contributed to the separation of samples based upon changes in relative abundance. Overall, just two and four more oribatid species were found in the oldest birch compared with the heather moorland at the two sites. Some of these species have been found in heather moorland elsewhere in the United Kingdom. Consequently, our results suggest that many oribatid species are able to persist in two distinctly different habitats in this area. Further, a gradual onset of secondary succession arising from tree invasion, as opposed to, for example, the cessation of agriculture or tree harvesting, may not lead to an overall increase in oribatid species richness in this environment. Our results support synecology studies conducted in Europe that indicate that many oribatid species are able to persist in a wide range of humus forms and vegetation types

Plant secondary metabolite polymorphisms and the extended chemical phenotype

As it was originally proposed, the extended phenotype complised 'all effects of a gene upon the world' (Dawkins, 1989) and pmtrayed how the effects of a gene borne by an organism influenced its biotic and abiotic environments. The consideration of indirect genetic effects, in which an organism's phenotype becomes part of the selective environment of conspecifics (Wolf et al., 1998), was developed rigorously in the population genetics context and the concept subsequently extended to include effects on heterospecifics (Whitham et al., 2003). The extended phenotype concept has been adopted as a framework by some evolutionary biologists and ecologists to study the roles of plant secondary metabolites (PSMs) since Whitham et al. (2003) used helitable variation in tissue tannin concentrations among Populus species and hybrids to develop the concept of community and ecosystem genetics (Antonovics, 1992)

Average species richness (mean ± s.e., n = 8) at 0–6 cm depth found in the two treatments for the biotic groups sampled.

<p>Letters indicate significant within-group differences between treatments (one-way ANOVA with blocks).</p

Average species richness (mean ± s.e., n = 8) at 0–3 cm depth found in the heterogeneous treatment for the biotic groups sampled.

<p>Both sampling regimes used in the heterogeneous treatment are presented: d3 represents the same depth as sampled in the homogeneous treatment, whereas mix represents pooled samples collected across shallow (3 cm), medium (7.5 cm) and deep (12 cm) organic horizons.</p

Summary of abundance data (mean ± s.e., n = 8) of mesostigmatid and oribatid mites, collembolans and nematodes (ind. ×10³ m⁻²) in the top 0–6 cm of the organic horizon in treatments representing either homogeneous or heterogeneous soil environment.

<p><i>F</i> statistic and associated significance level (one-way ANOVA with blocks; bold if significant) are presented.</p

Schematic presentation of the experimental treatments.

<p>a) View from the side to show the organic layer depths for both treatments representing either homogeneous or heterogeneous environment. The homogeneous treatment had the same organic (O) horizon depth (7.5 cm) throughout the box whilst the heterogeneous treatment had a mix of 5 different O-horizon depths ranging from a deep (12 cm, d1) to a shallow (3 cm, d5) O-horizon in steps of 2.25 cm increase in depth. b) View from above to show the distribution of the depths throughout each replicate. In the homogeneous treatments three cells (7.5 cm, d3) were sampled to make up one composite sample for each biotic group. In the heterogeneous treatment three cells with the same depth as the homogeneous treatment (d3) were sampled to make up one composite sample (single depth sample), and another composite sample was collected by sampling each of a cell with d1, d3 and d5 (mixed depth sample).</p