Efficient discrimination of oat and pea roots by cluster analysis of Fourier transform infrared (FTIR) spectra

Understanding belowground competition of plants requires a simple method for species identification of plant roots. This study investigates Fourier transform infrared (FTIR)-attenuated total reflexion (ATR) spectroscopy followed by cluster analysis for the discrimination of pea and oat roots. Pea and oat plants were grown under various conditions – in moist paper, soil-compost mixture, soil, in the greenhouse and field – to enhance the intra-species variability of their chemical composition. FTIR-ATR spectra of young-to-old roots from four independent experiments were recorded and represent, like a fingerprint, the chemical sample composition such as lipids, proteins, carbohydrates, etc. To group the spectra according to their spectral similarity in a dendrogram, cluster analysis was performed. The experimental approach discriminated pea and oat roots 100% successfully. The perfect discrimination of pea and oat roots, even from intercropped plants, strikingly demonstrates the potential of the method.     

Predicting loss and fragmentation of habitat of the vulnerable subtropical rainforest tree Macadamia integrifolia with models developed from compiled ecological data

Habitat models are widely used in ecology, however there are relatively few studies of rare species, primarily because of a paucity of survey records and lack of robust means of assessing accuracy of modelled spatial predictions. We investigated the potential of compiled ecological data in developing habitat models for Macadamia integrifolia, a vulnerable mid-stratum tree endemic to lowland subtropical rainforests of southeast Queensland, Australia. We compared performance of two binomial models—Classification and Regression Trees (CART) and Generalised Additive Models (GAM)—with Maximum Entropy (MAXENT) models developed from (i) presence records and available absence data and (ii) developed using presence records and background data. The GAM model was the best performer across the range of evaluation measures employed, however all models were assessed as potentially useful for informing in situ conservation of M. integrifolia, A significant loss in the amount of M. integrifolia habitat has occurred (p < 0.05), with only 37% of former habitat (pre-clearing) remaining in 2003. Remnant patches are significantly smaller, have larger edge-to-area ratios and are more isolated from each other compared to pre-clearing configurations (p < 0.05). Whilst the network of suitable habitat patches is still largely intact, there are numerous smaller patches that are more isolated in the contemporary landscape compared with their connectedness before clearing. These results suggest that in situ conservation of M. integrifolia may be best achieved through a landscape approach that considers the relative contribution of small remnant habitat fragments to the species as a whole, as facilitating connectivity among the entire network of habitat patches.     

Is higher-taxon analysis an useful surrogate of species richness in studies of Neotropical mammal diversity?

The usefulness of higher-taxon analysis was investigated at genus-, family-, and order-levels; to estimate the species richness of mammals from localities in the Amazon and Central America. The dataset allowed the test of higher-taxon approach through all orders of mammals, and within the most speciose orders: Didelphimorphia, Chiroptera, Primates, and Rodentia. Analyses with all orders together, Didelphimorphia, Chiroptera, and Rodentia showed that family and order richness were not related with species richness. In all cases, there were significant and positive relationships between generic and species richness. Within Primates, family richness was related to the number of species, but weaker than the relationship between generic and species richness. In summary, higher-taxon approach, at the generic level, is a useful surrogate of species richness for mammals that occur in the Amazon and Central America.     

Estimating allelic richness and its diversity

Assessing allelic richness in a set of populations requires that variations of sample size be taken into account. One way of doing this is to estimate the number of alleles expected in samples of specified size, using the rarefaction method applied in ecology. An alternative method, based on extrapolation, consists of adding to the number of alleles actually seen in a population the expected number of alleles missing, given the number of genes examined in the population and the allelic frequencies observed over the whole set of populations. Heterogeneity of allelic richness across populations and across loci can also be tested in this framework by numerical re-sampling. Both methods provide a measure of “private” allelic richness, a useful criterion in genetic diversity preservation, by allowing evaluation of the uniqueness of each population in terms of allele numbers. The two methods are compared on isozyme loci in the argan tree of Morocco and on microsatellite genotypes in the European pig. In both species, allelic richness and gene diversity behave quasi-independently over the populations compared and a higher differentiation is observed in allelic richness compared to gene diversity. In general, the rarefaction technique is sensitive to the sample size of reference and may lack sensitivity to rare alleles when the sample size of reference is small. Extrapolation may thus be recommended especially when the sample sizes of the populations are either low on average or highly unbalanced among populations.     

Maize–soybean intercropping effect on yield productivity,weed control and diversity in northern Ghana

The cereal–legume cropping system is a common practice across the tropical world. However, there are limited quantitative data on the effect of cereal–legume intercropping on weed species diversity. A study was conducted in the Guinea savanna zone of Ghana to evaluate the effect of maize–soybean intercropping on yield productivity and weed species control. The treatments used include three maize maturity types (extra‐early: Abontem, early: Sammaz 27 and medium: Obatanpa) intercropped with soybean at three intraspacing (10, 20 and 30 cm), and their sole crop treatments were laid in a randomized complete block design with three replications. Results showed that the land equivalent ratio (LER) for the intercrops was above 1, indicating better intercrop productivity than the sole crops. An average of 40% land was saved for the intercrops compared with the sole crops. Intercropping Sammaz 27 maize with soybean significantly increased LER by 9% compared to the other types. Intercropping maize with soybean significantly reduced weed biomass at 6 and 9 weeks after planting (WAP) and at harvest relative to the sole maize. The weed biomass at 6 and 9 WAP and harvest increased (p < .05) with increasing soybean intraspacing. The grass and broadleaf weed species count at 6 WAP and harvest from the sole crops were significantly higher than that of the intercrops. The results suggest that intercropping early maize maturity type with soybean at 10 cm intraspacing could be used to increase grain yield, LER and control of grass and broadleaf weeds in a maize‐based cropping system in the Guinea savanna zones of West Africa.     

赣江流域袁河底栖动物群落结构及其水质生物学评价

2009年6、11月和2010年4月共3个水情期（即丰、枯和平水期）对赣江流域一级支流袁河底栖动物群落结构进行了调查。结果表明袁河流域底栖动物17种,隶属于3门5纲12科,其中寡毛类4种,蛭类1种,腹足类5种,瓣鳃类4种,水生昆虫类3种。袁河底栖动物3期总密度和总生物量分别为1 762.29 ind./m2和982.37 g/m2,密度上摇蚊占优势,生物量上铜锈环棱螺占优势。不同水情期现存量也存在差异,平水期的密度和生物量均比丰水期、枯水期的大;丰水期的密度比枯水期的大,而生物量却比枯水期的小。袁河底栖动物优势种为摇蚊、铜锈环棱螺、河蚬和方格短沟蜷。Shannon-Wiener指数、Margalef指数表明袁河底栖动物多样性存在季节性变化,且下游多样性比上中游复杂;Shannon-Wiener指数和FBI指数的结果表明袁河水质已受到不同程度污染。     

Patch connectivity and genetic diversity conservation in the federally endangered and narrowly endemic plant species Astragalus albens (Fabaceae)

To evaluate the sufficiency of US federal critical habitat designations and a proposed conservation plan in promoting the long-term persistence of the endangered plant Astragalus albens, patterns of genetic diversity and landscape connectivity were examined. A. albens harbors substantial genetic variation and shows no evidence of historic bottlenecks, suggesting little risk of extinction due to genetic homogeneity (A = 2.40; P = 0.50) or inbreeding (f = −0.08) within occurrences. Low genetic differentiation among occurrences (θ_p = 0.01) indicates relatively high gene flow or little genetic drift. The 91 patches of A. albens were connected into a single network at a distance of 2100 m; 94% of patches were <1000 m from at least one other patch. Managing ecological conditions that maintain large population sizes and connectivity among populations throughout the species’ ecological and geographic ranges will most likely conserve existing diversity. Both reserve networks partially accomplish these goals by including most extant occurrences and >89% of the aerial extent of the species, including the largest populations, and capturing all detected alleles. However, both conservation networks fail to conserve occurrences from one portion of the species’ range, possibly speeding loss of unique local adaptations. In addition, connectivity of the whole network is reduced with the 65 patches designated as critical habitat being connected at a distance of 6200 m and the proposed reserve sites being connected at a distance of 9500 m. Although total network connectivity would be reduced, connectivity at scales most relevant to gene flow (e.g., <1000 m) remains sufficiently in tact to provide a relatively promising outlook for species persistence.     

秦岭山地“七药”植物在海拔梯度上的种域分布特征

物种丰富度沿海拔梯度的分布格局成为生物多样性研究的热点。以秦岭山地七药植物为研究对象,分析了该区域七药植物物种丰富度的垂直分布格局,以及不同种域宽度组的物种丰富度沿海拔梯度的变化规律,并分析了种域宽度与海拔梯度的关系,检验其是否符合Rapoport法则。结果表明,秦岭山地七药植物的物种丰富度随着海拔的升高呈现先增加后减小的趋势,最大值出现在海拔1 800m;在不同海拔段,各组的物种丰富度值大小均与种域宽度正相关,即种域越宽的组资源植物种数越多;物种丰富度垂直分布格局的形成与海拔所反映的水、热条件以及物种分布的界限有关;秦岭山地七药植物的种域宽度和海拔梯度有较弱的正相关关系,基本支持Rapoport法则。     

山西省虫生真菌资源应用初步评价

为了虫生真菌资源进一步应用到害虫防治上,本文选取山西省虫生真菌优势类群中的绿僵菌(Metarhizium)、白僵菌(Beauveria)、拟青霉(Paecilemyces)、轮枝菌(Verticillium)、曲霉菌(Aspergillus)和青霉菌(Penicillium)6个属中9种致病虫生真菌,运用喷雾法和涂抹法进行生物学测定,并对其在害虫生物防治的应用前景进行了评价。结果表明,绿僵菌和轮枝菌具有良好的高效低毒特点,可以考虑作为生防制剂的备选菌株进行田间防效试验。     

佳木斯市4所公园大型真菌多样性与相似度分析

[目的]了解佳木斯市4所公园大型真菌的多样性和相似度。[方法]对佳木斯市4所公园大型真菌进行采样调查,并通过分析大型真菌的分布情况,结合园林植物与野生植物的研究数据,分析了大型真菌多样性情况与植物、生态环境之间的相关性。[结果]佳木斯市4所公园不同生境有大型真菌5科16属25种,大型真菌样本共610份,其中优势种9种。多样性指数、均匀度指数及优势度指数均以西浦森林公园最高,西浦森林公园和双拥公园的相似度最高,杏林湖公园和绿云公园的相似度最低。[结论]研究结果为佳木斯市大型真菌的保护与开发提供了理论依据。