Macroecological patterns in flower colour are shaped by both biotic and abiotic factors

There is a wealth of research on the way interactions with pollinators shape flower traits. However, we have much more to learn about influences of the abiotic environment on flower colour. We combine quantitative flower colour data for 339 species from a broad spatial range covering tropical, temperate, arid, montane and coastal environments from 9.25ºS to 43.75ºS with 11 environmental variables to test hypotheses about how macroecological patterns in flower colouration relate to biotic and abiotic conditions. Both biotic community and abiotic conditions are important in explaining variation of flower colour traits on a broad scale. The diversity of pollinating insects and the plant community have the highest predictive power for flower colouration, followed by mean annual precipitation and solar radiation. On average, flower colours are more chromatic where there are fewer pollinators, solar radiation is high, precipitation and net primary production are low, and growing seasons are short, providing support for the hypothesis that higher chromatic contrast of flower colours may be related to stressful conditions. To fully understand the ecology and evolution of flower colour, we should incorporate the broad selective context that plants experience into research, rather than focusing primarily on effects of plant–pollinator interactions

Mitochondrial phosphoenolpyruvate carboxykinase (PEPCK-M) and serine biosynthetic pathway genes are co-ordinately increased during anabolic agent-induced skeletal muscle growth

We aimed to identify novel molecular mechanisms for muscle growth during administration of anabolic agents. Growing pigs (Duroc/(Landrace/Large-White)) were administered Ractopamine (a beta-adrenergic agonist; BA; 20ppm in feed) or Reporcin (recombinant growth hormone; GH; 10mg/48hours injected) and compared to a control cohort (feed only; no injections) over a 27-day time course (1, 3, 7, 13 or 27-days). Longissimus Dorsi muscle gene expression was analyzed using Agilent porcine transcriptome microarrays and clusters of genes displaying similar expression profiles were identified using a modified maSigPro clustering algorithm. Anabolic agents increased carcass (p=0.002) and muscle weights (Vastus Lateralis: p<0.001; Semitendinosus: p=0.075). Skeletal muscle mRNA expression of serine/one-carbon/glycine biosynthesis pathway genes (Phgdh, Psat1 and Psph) and the gluconeogenic enzyme, phosphoenolpyruvate carboxykinase-M (Pck2/PEPCK-M), increased during treatment with BA, and to a lesser extent GH (p<0.001, treatment x time interaction). Treatment with BA, but not GH, caused a 2-fold increase in phosphoglycerate dehydrogenase (PHGDH) protein expression at days 3 (p<0.05) and 7 (p<0.01), and a 2-fold increase in PEPCK-M protein expression at day 7 (p<0.01). BA treated pigs exhibit a profound increase in expression of PHGDH and PEPCK-M in skeletal muscle, implicating a role for biosynthetic metabolic pathways in muscle growth

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals &lt;1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Biogeochemical mapping of metal contamination from mine tailings using field-portable XRF

Trace and major element composition of selected plant species and parts may be used to map geochemical dispersion from mineral deposits and contaminated areas. This study examines the application of field-portable X-ray fluorescence spectrometry (fpXRF) in obtaining real-time biogeochemical data. In situ analysis of parts of black and silver wattle (Acacia mearnsii De Wild. and Acacia dealbata Link) was conducted to map the extent of contamination surrounding the former Woodlawn base metal mine. High levels of ore-related elements were detected in the bark of these species in a zone extending up to 1 km down-drainage from the tailing ponds. Major elements are more elevated in bark on the side of the trees facing the tailings ponds and correlations between trace and major elements indicate dust contamination. The penetration distance for X-rays is dependent on the energy of the secondary X-rays measured, with the maximum depth of penetration in bark and leaf material <30 mm. There was a close correlation for most elements between the fpXRF and laboratory-based XRF analysis but with element-dependent attenuation by the organic matrix. Providing there is consistency in sampling and analytical methodology, in situ fpXRF analysis of vegetation is an effective method in both contamination surveys and biogeochemical mineral exploration for a range of trace and major elements

Prickly pairs: The proportion of spinescent species does not differ between islands and mainlands

Aims: Organisms on islands are thought to escape biotic pressure and lose defensive capabilities. However, broadscale, evidence-based tests of this idea are rare. In this study, we asked: (i) whether the proportion of spinescent plant species differed between islands and mainlands and (ii) whether the proportion of spinescent species increased with increasing island area and with decreasing island distance to mainland. Methods: We compiled species lists for 18 island-mainland pairs around Australia. We classified 1129 plant species as spinescent or non-spinescent using published species descriptions. Important Findings: There was no significant difference between the proportion of spinescent species found on islands and on mainlands. Proportions of spinescent species were not significantly related to island area or distance to mainland. Our results suggest that spinescence is just as important to island plants as it is to mainland plants, even for plants inhabiting small or distal islands. This is unexpected, given prevailing thought and previous work on island-mainland comparisons. Our study demonstrates the importance of testing well-accepted yet untested ideas

Abiotic and biotic predictors of macroecological patterns in bird and butterfly coloration

Animal color phenotypes are invariably influenced by both their biotic community and the abiotic environments. A host of hypotheses have been proposed for how variables such as solar radiation, habitat shadiness, primary productivity, temperature, rainfall, and community diversity might affect animal color traits. However, while individual factors have been linked to coloration in specific contexts, little is known about which factors are most important across broad taxonomic and geographic scales. Using data collected from 570 species of birds and 424 species of butterflies from Australia, which inhabit an area spanning a latitudinal range of 35° and covering deserts, tropical and temperate forests, savannas, and heathlands, we test multiple hypotheses from the coloration literature and assess their relative importance. We show that bird and butterfly species exhibit more reflective and less saturated colors in better-lit environments, a pattern that is robust across an array of variables expected to influence the intensity or quality of ambient light in an environment. Both taxa display more diverse colors in regions with greater net primary production and longer growing seasons. Models that included variables related to energy inputs and resources in ecosystems have better explanatory power for bird and butterfly coloration overall than do models that included community diversity metrics. However, the diversity of the bird community in an environment was the single most powerful predictor of color pattern variation in both birds and butterflies. We observed strong similarities across taxa in the covariance between color and environmental factors, suggesting the presence of fundamental macroecological drivers of visual appearance across disparate taxa