Molecular cytogenetics of Androctonus scorpions: an oasis of calm in the turbulent karyotype evolution of the diverse family Buthidae

After years of qualitative and subjective study, quantitative colour science is now enabling rapid measurement, analysis and comparison of colour traits. However, it has not been determined how many replicates one needs to accurately quantify a species' colours for studies aimed at broad cross‐species trait comparison. We address this major methodological knowledge gap. We first quantified and assessed the variance in colour within and between species. Reflectance spectra of flowers from ten plant species and plumage of 20 bird species were measured using a spectrometer, and reflectance (i.e. brightness) and tetrahedral colour‐space coordinates were calculated. analysis of variance (ANOVA) analyses indicate that there is far more variation in the colours of birds and flowers between species (> 77%) than within species. A Mean Absolute Deviation from the Mean test was applied to indicate the sampling replication required for each species. Tetrahedral coordinates were sampled precisely with only one individual per species. Greater replication was needed to sample reflectance with the desired precision, particularly for darker coloured species. Our findings will allow researchers to allocate their sampling effort in a way that maximises the precision of their colour data collection. The fact that only a few replicates per species are necessary will greatly facilitate broad cross‐species comparisons of colour in the future. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 114 , 69–81.     

Low‐Temperature Behaviour of Charge Transfer Excitons in Narrow‐Bandgap Polymer‐Based Bulk Heterojunctions

Photoluminescence studies of the charge transfer exciton emission from a narrow‐bandgap polymer‐based bulk heterojunction are reported. The quantum yield of this emission is as high as 0.03%. Low temperature measurements reveal that while the dynamics of the singlet exciton is slower at low temperature, the dynamics of the charge transfer exciton emission is temperature independent. This behavior rules out any diffusion process of the charge transfer excitons and energy transfer from these interfacial states toward lower lying states. Photoluminescence measurements performed on the device under bias show a reduction (but not the total suppression) of the charge transfer exciton recombination. Finally, based on the low temperature results the role of the charge transfer excitons and the possible pathways to populate them are identified.     

The physical mechanism of cuticular color in Phelotrupes auratus (Coleoptera,Geotrupidae)

The physical mechanism of cuticular color in Phelotrupes auratus was investigated by polarized inspection, spectrophotometry and transmission electron microscopy (TEM). No color change was observed when viewed through either a right‐ or left‐handed circular polarizer. Further, under the incidence of linearly polarized light, the reflected intensity was markedly reduced when observed through a linear polarizer set with its optical axis perpendicular to that of the incident light. These results indicate that P. auratus does not possess any circularly polarizing reflectors. TEM observations revealed a total of ten or twelve thin layers (about 60–120 nm in thickness) of two types of material (electron‐dense and electron‐lucent) alternately stacked in the epicuticle. The thickness of the layers in the different color forms of the beetle corresponded to the peak wavelengths in the reflectance spectra, λmax(α), with thicker layers found in beetles exhibiting reflectance peaks at longer wavelengths and vice versa. Based on these findings, we concluded that all the cuticular color forms of P. auratus were not produced by a circularly polarizing reflector but by a simple multilayer reflector.     

General method for selective labelling of double‐chain cysteine‐rich peptides with a lanthanide chelate via solid‐phase synthesis

The use of lanthanides in preference to radioisotopes as probes for various biological assays has gained enormous popularity. The introduction of lanthanide chelates to peptides/proteins can be carried out either in solution using a commercially available labelling kit or by solid‐phase peptide synthesis using an appropriate lanthanide chelate. Herein, a detailed protocol for the latter is provided for the labelling of peptides or small proteins with diethylenetriamine‐N, N, N″, N″‐tetra‐tert‐butyl acetate‐N′‐acetic acid (DTPA) chelate or other similar chelates on a solid support using a chimeric insulin‐like peptide composed of human insulin‐like peptide 5 (INSL5) A‐chain and relaxin‐3 B‐chain as a model peptide. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.     

Learning rules for optimal selection in a varying environment: mate choice revisited

The quality of a chosen partner can be one of the most significantfactors affecting an animal's long-term reproductive success.We investigate optimal mate choice rules in an environment wherethere is both local variation in the quality of potential mateswithin each local mating pool and spatial (or temporal) variationin the average quality of the pools themselves. In such a situation,a robust rule that works well across a variety of environmentswill confer a significant reproductive advantage. We formulatea full Bayesian model for updating information in such a varyingenvironment and derive the form of the rule that maximizes expectedreward in a spatially varying environment. We compare the theoreticalperformance of our optimal learning rule against both fixedthreshold rules and simpler near-optimal learning rules andshow that learning is most advantageous when both the localand environmental variances are large. We consider how optimalsimple learning rules might evolve and compare their evolutionwith that of fixed threshold rules using genetic algorithmsas minimal models of the relevant genetics. Our analysis pointsup the variety of ways in which a near-optimal rule can be expressed.Finally, we describe how our results extend to the case of temporallyvarying environments.     

景观破碎化对东北虎主要猎物种群动态影响的模拟

以完达山东部地区的现实景观为背景,采用空间直观种群模型LAPS和情景模拟相结合的"虚拟实验"途径,模拟了在10个不同破碎化程度的景观情景中东北虎的主要猎物于1992-2011年间的种群动态,评价了完达山东部地区当前的景观破碎化程度对东北虎主要猎物种群动态的影响。结果表明:LAPS模型准确刻画了研究区东北虎主要猎物种群数量急剧下降的趋势,2002年模拟的东北虎主要猎物的种群数量和实测值之间没有显著差异,马鹿、野猪和狍子的P值分别为0.8651、0.9534和0.2836;不同生境类型的种群密度数据与实测值之间均没有显著差异,其中阔叶林生境中的马鹿、野猪和狍子的P值分别为0.8521、0.9447和0.3152;在灌丛生境中的马鹿、野猪和狍子的P值分别为0.8846、0.9576和0.2415。斑块类型和景观水平上的格局指标变化趋势表明由于农田扩张导致10个景观情景的破碎化程度逐渐增加,景观水平的破碎化程度低于斑块类型水平。方差分析显示10个景观情景中的种群数量没有显著差异,马鹿、野猪和狍子的P值分别为0.8516、0.2624和0.7636,说明研究区当前的景观破碎化程度对种群动态影响并不显著。完达山东部地区存在盗猎等人为干扰,导致了东北虎主要猎物的数量远低于环境容纳量,景观破碎化虽然在局部地区较为严重,但完达山东部地区整体上景观破碎化并不强烈,该地区景观破碎化的效应尚未显现。认为控制盗猎等人为干扰是增加该地区东北虎主要猎物的数量、实现东北虎种群恢复所应优先采取的措施。     

The responses of Moso bamboo (Phyllostachys heterocycla var. pubescens) forest aboveground biomass to Landsat TM spectral reflectance and NDVI

Bamboo is a special forest type in subtropical regions of china. Its huge biomass and carbon storage and its ecological function play an important role in global carbon sink. In this paper, Moso bamboo (Phyllostachys heterocycla var. pubescens) forest in Anji county, Zhejiang province, China was selected to examine the relationships between Landsat Thematic Mapper (TM) data, and aboveground biomass (AGB, Kg), This research indicates that (1) near infrared (TM4) and mid-infrared bands (TM5,TM7) are more important in explaining Moso bamboo AGB than the visible bands. In particular, TM band5 has higher path coefficient with AGB than any other TM bands, implying its important role in explaining Moso bamboo AGB; (2) the Normalized Difference Vegetation Index (NDVI) has weak correlation with Moso bamboo AGB, however, other vegetable indices such as Perpendicular Vegetation Index (PVI), Enhanced Vegetation Index(EVI), and Soil Adjust Vegetation Index (SAVI) which are related to soil adjustment parameters are significantly correlated with Moso bamboo AGB; (3) the new vegetation index developed in this paper is significantly correlated with Moso bamboo AGB (correlation coefficient is 0.48), and has higher correlation coefficient (R) than any other selected vegetation indices, implying that this new vegetation index can better explain Moso bamboo AGB than any other vegetation indices.     

Evolution of specialization in a spatially continuous environment

We study the evolution of specialization in a spatially continuous (one‐dimensional) environment divided into two habitats; we use a general trade‐off function relating fitnesses in the two habitats and illustrate our results with two classical trade‐off functions. We show that the population can either reach an intermediate value of the trait and be moderately adapted to both habitats (1 generalist), or split into two locally adapted subpopulations (2 specialists). We recover the qualitative results obtained with simpler metapopulation models with island migration: the evolutionary outcome depends on the concavity of the trade‐off, on the proportion of each habitat and on migration. Our quantitative prediction on migration, however, depends on isolation by distance. Our spatially explicit model may thus be particularly useful to describe the evolutionary dynamics of specialization in, perhaps, more realistic ecological scenarios.     

Pressure effect on the stability and the conformational dynamics of the D-Galactose/D-Glucose-binding protein from Escherichia coli

The effect of the pressure on the structure and stability of the D-Galactose/D-Glucose binding protein (GGBP) from Escherichia coli was studied by steady-state and time-resolved fluorescence spectroscopy, and the ability of glucose ligand to stabilize the GGBP structure was also investigated. Steady-state fluorescence experiments showed a marked quenching of fluorescence emission of GGBP in the absence of glucose. Instead, the presence of glucose seems to stabilize the structure of GGBP at low and moderate pressure values. Time-resolved fluorescence measurements showed that the GGBP taumean in the absence of glucose varies significantly up to 600 bar, while in the presence of the ligand it is almost unaffected by pressure increase up to 600 bar. The effect of the pressure on GGBP was also studied by molecular dynamics simulations. The simulation data support the spectroscopic results and confirm that the presence of glucose is able to contrast the negative effects of pressure on the protein structure. Taken together, the spectroscopic and computer simulation studies suggest that at pressure values up to 2000 bar the structure of GGBP in the absence of glucose remains folded, but a significant perturbation of the protein secondary structures can be detected. The binding of glucose reduces the negative effect of pressure on protein structure and confers protection from perturbation especially at moderate pressure values.