Trophic resource partitioning and competition between the two sibling bat species Myotis myotis and Myotis blythii

1. Niche theory predicts that the stable coexistence of species within a guild should be associated, if resources are limited, with a mechanism of resource partitioning. Using extensive data on diets, the present study attempts: (i) to test the hypothesis that, in sympatry, the interspecific overlap between the trophic niches of the sibling bat species Myotis myotis and M. blythii-which coexist intimately in their roosts-is effectively lower than the two intraspecific overlaps; (ii) to assess the role played by interspecific competition in resource partitioning through the study of trophic niche displacement between several sympatric and allopatric populations. 2. Diets were determined by the analysis of faecal samples collected in the field from individual bats captured in various geographical areas. Trophic niche overlaps were calculated monthly for all possible intraspecific and interspecific pairs of individuals from sympatric populations. Niche breadth was estimated from: (i) every faecal sample; (ii) all the faecal samples collected per month in a given population (geographical area). 3. In every population, the bulk of the diets of M. myotis and M. blythii consisted of, respectively, terrestrial (e.g. carabid beetles) and grass-dwelling (mostly bush crickets) prey. All intraspecific trophic niche overlaps were significantly greater than the interspecific one, except in Switzerland in May when both species exploited mass concentrations of cockchafers, a non-limiting food source. This clearcut partitioning of resources may allow the stable, intimate coexistence observed under sympatric conditions. 4. Relative proportions of ground-and grass-dwelling prey, as well as niche breadths (either individual or population), did not differ significantly between sympatry and allopatry, showing that, under allopatric conditions, niche expansion does not take place. This suggests that active interspecific competition is not the underlying mechanism responsible for the niche partitioning which is currently observed between M. myotis and M. blythii.

FTO genetic variants, dietary intake and body mass index: insights from 177,330 individuals.

FTO is the strongest known genetic susceptibility locus for obesity. Experimental studies in animals suggest the potential roles of FTO in regulating food intake. The interactive relation among FTO variants, dietary intake and body mass index (BMI) is complex and results from previous often small-scale studies in humans are highly inconsistent. We performed large-scale analyses based on data from 177,330 adults (154 439 Whites, 5776 African Americans and 17 115 Asians) from 40 studies to examine: (i) the association between the FTO-rs9939609 variant (or a proxy single-nucleotide polymorphism) and total energy and macronutrient intake and (ii) the interaction between the FTO variant and dietary intake on BMI. The minor allele (A-allele) of the FTO-rs9939609 variant was associated with higher BMI in Whites (effect per allele = 0.34 [0.31, 0.37] kg/m(2), P = 1.9 × 10(-105)), and all participants (0.30 [0.30, 0.35] kg/m(2), P = 3.6 × 10(-107)). The BMI-increasing allele of the FTO variant showed a significant association with higher dietary protein intake (effect per allele = 0.08 [0.06, 0.10] %, P = 2.4 × 10(-16)), and relative weak associations with lower total energy intake (-6.4 [-10.1, -2.6] kcal/day, P = 0.001) and lower dietary carbohydrate intake (-0.07 [-0.11, -0.02] %, P = 0.004). The associations with protein (P = 7.5 × 10(-9)) and total energy (P = 0.002) were attenuated but remained significant after adjustment for BMI. We did not find significant interactions between the FTO variant and dietary intake of total energy, protein, carbohydrate or fat on BMI. Our findings suggest a positive association between the BMI-increasing allele of FTO variant and higher dietary protein intake and offer insight into potential link between FTO, dietary protein intake and adiposity.

Under-reporting of dietary energy intake in five populations of the African diaspora.

Studies on the role of diet in the development of chronic diseases often rely on self-report surveys of dietary intake. Unfortunately, many validity studies have demonstrated that self-reported dietary intake is subject to systematic under-reporting, although the vast majority of such studies have been conducted in industrialised countries. The aim of the present study was to investigate whether or not systematic reporting error exists among the individuals of African ancestry (n 324) in five countries distributed across the Human Development Index (HDI) scale, a UN statistic devised to rank countries on non-income factors plus economic indicators. Using two 24 h dietary recalls to assess energy intake and the doubly labelled water method to assess total energy expenditure, we calculated the difference between these two values ((self-report - expenditure/expenditure) × 100) to identify under-reporting of habitual energy intake in selected communities in Ghana, South Africa, Seychelles, Jamaica and the USA. Under-reporting of habitual energy intake was observed in all the five countries. The South African cohort exhibited the highest mean under-reporting ( - 52·1% of energy) compared with the cohorts of Ghana ( - 22·5%), Jamaica ( - 17·9%), Seychelles ( - 25·0%) and the USA ( - 18·5%). BMI was the most consistent predictor of under-reporting compared with other predictors. In conclusion, there is substantial under-reporting of dietary energy intake in populations across the whole range of the HDI, and this systematic reporting error increases according to the BMI of an individual.

Lost in translation: dietary management of cardiovascular risk factors is seldom implemented.

OBJECTIVE: To assess dietary management of cardiovascular risk factors (CVRFs) in the general population. METHOD: Cross-sectional study conducted between 2009 and 2012 on 4811 participants (2567 women, 58±11years) living in Lausanne, Switzerland. RESULTS: Sixteen percent of participants diagnosed with overweight/obesity reported a slimming diet. Slimming diet was associated with diagnosis of hypertension: Odds ratio and (95% confidence interval): 0.61 (0.40-0.93); older age [0.84 (0.58-1.21), 0.79 (0.53-1.18) and 0.47 (0.27-0.81) for [50-60[, [60-70[ and [70+ years, respectively]; female gender [1.84 (1.36-2.48)] and diagnosis of diabetes [2.16 (1.13-4.12)]. Only 8% of participants diagnosed with hypertension reported a low-salt diet. Low-salt diet was associated with antihypertensive drug treatment [2.17 (1.28-3.68)] and diagnosis of diabetes [2.72 (1.26-5.86)]. One-third of participants diagnosed with dyslipidemia reported a low-fat diet. Low-fat diet was associated with female gender [1.47 (1.17-1.86)]; older age [1.29 (0.89-1.87), 1.71 (1.18-2.48) and 2.01 (1.33-3.03) for [50-60[, [60-70[ and [70+ years, respectively]; hypolipidemic drug treatment [OR=1.68 (1.29-2.18)]; current smoking [0.70 (0.51-0.96)] and obesity [0.67 (0.45-1.00)]. Approximately half of participants diagnosed with diabetes reported an antidiabetic diet. Antidiabetic diet was associated with current smoking [0.44 (0.22-0.88)] and antidiabetic drug treatment [OR=3.26 (1.81-5.86)]. CONCLUSION: Dietary management of CVRFs is seldom implemented in Switzerland.

Climate niche conservatism does not explain restricted distribution patterns in Tynanthus (Bignonieae, Bignoniaceae)

Studies on niche evolution allow us to establish how species niches have changed over time as well as to identify how long-term evolutionary processes have led to present-day species distributions. Here, we investigate the patterns of climatic niche evolution in Tynanthus (Bignonieae, Bignoniaceae), a genus comprising narrowly distributed species. We test the hypothesis that niche conservatism has played an important role in the diversification history of this group of Neotropical lianas. For that, we perform univariate and multivariate comparisons between species' climatic niches and associated environmental data with information on species' phylogenetic relationships. We encountered considerable divergence in niches among species, indicating that niche conservatism in climatic variables has does not seem to havenot played a key role in the diversification of the genus. Our results are used as a basis to discuss patterns of ecological niche evolution in the group and to suggest novel approaches for future analyses.

Does phylogeographic structure relate to climatic niche divergence? A test using maritime pine (Pinus pinaster Ait.)

Aim To disentangle the effects of environmental and geographical processes driving phylogenetic distances among clades of maritime pine (Pinus pinaster). To assess the implications for conservation management of combining molecular information with species distribution models (SDMs; which predict species distribution based on known occurrence records and on environmental variables). Location Western Mediterranean Basin and European Atlantic coast. Methods We undertook two cluster analyses for eight genetically defined pine clades based on climatic niche and genetic similarities. We assessed niche similarity by means of a principal component analysis and Schoener's D metric. To calculate genetic similarity, we used the unweighted pair group method with arithmetic mean based on Nei's distance using 266 single nucleotide polymorphisms. We then assessed the contribution of environmental and geographical distances to phylogenetic distance by means of Mantel regression with variance partitioning. Finally, we compared the projection obtained from SDMs fitted from the species level (SDMsp) and composed from the eight clade-level models (SDMcm). Results Genetically and environmentally defined clusters were identical. Environmental and geographical distances explained 12.6% of the phylogenetic distance variation and, overall, geographical and environmental overlap among clades was low. Large differences were detected between SDMsp and SDMcm (57.75% of disagreement in the areas predicted as suitable). Main conclusions The genetic structure within the maritime pine subspecies complex is primarily a consequence of its demographic history, as seen by the high proportion of unexplained variation in phylogenetic distances. Nevertheless, our results highlight the contribution of local environmental adaptation in shaping the lower-order, phylogeographical distribution patterns and spatial genetic structure of maritime pine: (1) genetically and environmentally defined clusters are consistent, and (2) environment, rather than geography, explained a higher proportion of variation in phylogenetic distance. SDMs, key tools in conservation management, better characterize the fundamental niche of the species when they include molecular information.

Dietary intake according to gender and education : a twenty-year trend in a Swiss adult population

We assessed trends in dietary intake according to gender and education using repeated cross-sectional, population-based surveys conducted between 1993 and 2012 in Geneva, Switzerland (17,263 participants, 52.0 ± 10.6 years, 48% male). In 1993-1999, higher educated men had higher monounsaturated fatty acids (MUFA), carotene and vitamin D intakes than lower educated men, and the differences decreased in 2006-2012. In 1993-1999, higher educated women had higher fiber, iron, carotene, vitamin D and alcohol intakes than lower educated women, and the differences decreased in 2006-2012. Total energy, polyunsaturated fatty acids, retinol and alcohol intakes decreased, while mono/disaccharides, MUFA and carotene intake increased in both genders. Lower educated men had stronger decreases in saturated fatty acid (SFA) and calcium intakes than higher educated men: multivariate-adjusted slope and 95% confidence interval -0.11 (-0.15; -0.06) vs. -0.03 (-0.08; 0.02) g/day/year for SFA and -5.2 (-7.8; -2.7) vs. -1.03 (-3.8; 1.8) mg/day/year for calcium, p for interaction <0.05. Higher educated women had a greater decrease in iron intake than lower educated women: -0.03 (-0.04; -0.02) vs. -0.01 (-0.02; 0.00) mg/day/year, p for interaction = 0.002. We conclude that, in Switzerland, dietary intake evolved similarly between 1993 and 2012 in both educational groups. Educational differences present in 1993 persisted in 2012.

Combining niche modelling and landscape genetics to study local adaptation: A novel approach illustrated using alpine plants

Understanding the factors that shape adaptive genetic variation across species niches has become of paramount importance in evolutionary ecology, especially to understand how adaptation to changing climate affects the geographic range of species. The distribution of adaptive alleles in the ecological niche is determined by the emergence of novel mutations, their fitness consequences and gene flow that connects populations across species niches. Striking demographical differences and source sink dynamics of populations between the centre and the margin of the niche can play a major role in the emergence and spread of adaptive alleles. Although some theoretical predictions have long been proposed, the origin and distribution of adaptive alleles within species niches remain untested. In this paper, we propose and discuss a novel empirical approach that combines landscape genetics with species niche modelling, to test whether alleles that confer local adaptation are more likely to occur in either marginal or central populations of species niches. We illustrate this new approach by using a published data set of 21 alpine plant species genotyped with a total of 2483 amplified fragment length polymorphisms (AFLP), distributed over more than 1733 sampling sites across the Alps. Based on the assumption that alleles that were statistically associated with environmental variables were adaptive, we found that adaptive alleles in the margin of a species niche were also present in the niche centre, which suggests that adaptation originates in the niche centre. These findings corroborate models of species range evolution, in which the centre of the niche contributes to the emergence of novel adaptive alleles, which diffuse towards niche margins and facilitate niche and range expansion through subsequent local adaptation. Although these results need to be confirmed via fitness measurements in natural populations and functionally characterised genetic sequences, this study provides a first step towards understanding how adaptive genetic variation emerges and shapes species niches and geographic ranges along environmental gradients.

DLL4 promotes continuous adult intestinal lacteal regeneration and dietary fat transport.

The small intestine is a dynamic and complex organ that is characterized by constant epithelium turnover and crosstalk among various cell types and the microbiota. Lymphatic capillaries of the small intestine, called lacteals, play key roles in dietary fat absorption and the gut immune response; however, little is known about the molecular regulation of lacteal function. Here, we performed a high-resolution analysis of the small intestinal stroma and determined that lacteals reside in a permanent regenerative, proliferative state that is distinct from embryonic lymphangiogenesis or quiescent lymphatic vessels observed in other tissues. We further demonstrated that this continuous regeneration process is mediated by Notch signaling and that the expression of the Notch ligand delta-like 4 (DLL4) in lacteals requires activation of VEGFR3 and VEGFR2. Moreover, genetic inactivation of Dll4 in lymphatic endothelial cells led to lacteal regression and impaired dietary fat uptake. We propose that such a slow lymphatic regeneration mode is necessary to match a unique need of intestinal lymphatic vessels for both continuous maintenance, due to the constant exposure to dietary fat and mechanical strain, and efficient uptake of fat and immune cells. Our work reveals how lymphatic vessel responses are shaped by tissue specialization and uncover a role for continuous DLL4 signaling in the function of adult lymphatic vasculature.

Dietary calcium restriction enhances cadmium-induced metallothionein synthesis in rats.

Experiments were conducted with adult male rats to investigate the effects of dietary calcium (Ca) restriction upon intake and tissue distribution of cadmium (Cd), and Cd-metallothionein (Mt) synthesis. Four groups of animals were fed either a low-Ca, semisynthetic diet (0.1% Ca) or the same diet supplemented with 0.8% Ca (normal diet). The caloric intake was similar in all groups. Two groups (low-Ca and normal diet) were used as controls, and two groups (low-Ca and normal diet) received 100 mg/l Cd (as CdCl2) in drinking water. Cd levels in liver, kidney, spleen and red cells were measured in all animals after 8 weeks of treatment. Concomitantly, Mt levels in plasma, liver and kidney were evaluated by radioimmunoassay. Ca deficiency entailed marked and significant increases in accumulation of Cd and synthesis of Mt in all assayed tissues. It is concluded that dietary Ca restriction, independent of caloric intake, enhances Cd intestinal absorption and tissue accumulation, which is followed by increased tissue Mt synthesis.

A matter of scale: apparent niche differentiation of diploid and tetraploid plants may depend on extent and grain of analysis

Aim: Emerging polyploids may depend on environmental niche shifts for successful establishment. Using the alpine plant Ranunculus kuepferi as a model system, we explore the niche shift hypothesis at different spatial resolutions and in contrasting parts of the species range. Location: European Alps. Methods: We sampled 12 individuals from each of 102 populations of R. kuepferi across the Alps, determined their ploidy levels, derived coarse-grain (100x100m) environmental descriptors for all sampling sites by downscaling WorldClim maps, and calculated fine-scale environmental descriptors (2x2m) from indicator values of the vegetation accompanying the sampled individuals. Both coarse and fine-scale variables were further computed for 8239 vegetation plots from across the Alps. Subsequently, we compared niche optima and breadths of diploid and tetraploid cytotypes by combining principal components analysis and kernel smoothing procedures. Comparisons were done separately for coarse and fine-grain data sets and for sympatric, allopatric and the total set of populations. Results: All comparisons indicate that the niches of the two cytotypes differ in optima and/or breadths, but results vary in important details. The whole-range analysis suggests differentiation along the temperature gradient to be most important. However, sympatric comparisons indicate that this climatic shift was not a direct response to competition with diploid ancestors. Moreover, fine-grained analyses demonstrate niche contraction of tetraploids, especially in the sympatric range, that goes undetected with coarse-grained data. Main conclusions: Although the niche optima of the two cytotypes differ, separation along ecological gradients was probably less decisive for polyploid establishment than a shift towards facultative apomixis, a particularly effective strategy to avoid minority cytotype exclusion. In addition, our results suggest that coarse-grained analyses overestimate niche breadths of widely distributed taxa. Niche comparison analyses should hence be conducted at environmental data resolutions appropriate for the organism and question under study.

Different rates of defense evolution and niche preferences in clonal and nonclonal milkweeds (Asclepias spp.).

Given the dual role of many plant traits to tolerate both herbivore attack and abiotic stress, the climatic niche of a species should be integrated into the study of plant defense strategies. Here we investigate the impact of plant reproductive strategy and components of species' climatic niche on the rate of chemical defense evolution in the milkweeds using a common garden experiment of 49 species. We found that across Asclepias species, clonal reproduction repeatedly evolved in lower temperature conditions, in species generally producing low concentrations of a toxic defense (cardenolides). Additionally, we found that rates of cardenolide evolution were lower for clonal than for nonclonal species. We thus conclude that because the clonal strategy is based on survival, long generation times, and is associated with tolerance of herbivory, it may be an alternative to toxicity in colder ecosystems. Taken together, these results indicate that the rate of chemical defense evolution is influenced by the intersection of life-history strategy and climatic niches into which plants radiate.