Estimating leaf area of warm‐season perennial legumes

Refining mathematical models may decrease labour and generate accurate estimates of leaf area in warm‐season perennial legumes. The aim of this study was to assess the use of mathematical models to determine the leaf area of four tropical forage legumes. Perennial legumes (Arachis pintoi, Stylosanthes spp., Calopogonium mucunoides and Neonotonia wightii) were collected, and an elliptical model and a corrected elliptical model were used to estimate leaf area. For comparison, linear models were also generated based on the leaflet area. The elliptical model was suitable for the initial forage peanut leaflets, while the corrected elliptical model proved suitable for estimating the area of the initial leaflets of all species as well as the terminal leaflets of forage peanut and stylo. The elliptical model could be used to estimate the area of both the initial and terminal leaflets only in stylo. Models were generated to estimate leaf area of all legumes requiring only the measurement of length and width from a single initial leaflet. In all of the studied legumes, the leaflet pairs were symmetrical, meaning the corrected elliptical model allows for the estimation of the leaflet area of each plant.     

DNA riboprinting analysis of Tilapia species and their hybrids using restriction fragment length polymorphisms of the small subunit ribosomal DNA

Morphometric, meristic and DNA riboprinting analyses of Tilapia species and their hybrids inhabiting the River Nile were examined. Morphometric data showed striking similarities and overlapping among Tilapia species, making it impossible to differentiate these species. Meristic characteristics revealed that Tilapia species could be identified into four major groups (Oreochromis niloticus, O. aureus, Sarotherodon galilaeus and Tilapia zillii). The lateral line scales differed significantly between the four Tilapia species, while the number of fin rays in the dorsal and anal fins differed significantly, differentiating three species (but not between O. niloticus and O. aureus). Restriction fragment length polymorphisms (RFLPs) of nuclear small sub‐unit ribosomal RNA (18S srRNA) gene were used to differentiate the species. Polymerase chain reaction‐restriction fragment length polymorphisms data provided a unique pattern for each species with a specific restriction enzyme. Two hybrids of Tilapia designated H₁ and H₂ were detected. The endonucleases SacII and ApaI differentiated H₁ and H₂. This research revealed a monophylogenetic relationship among all the studied Tilapia species.     

Sexual Dimorphism and Allometric Effects Associated With the Wing Shape of Seven Moth Species of Sphingidae (Lepidoptera: Bombycoidea)

Sexual dimorphism is a pronounced pattern of intraspecific variation in Lepidoptera. However, moths of the family Sphingidae (Lepidoptera: Bombycoidea) are considered exceptions to this rule. We used geometric morphometric techniques to detect shape and size sexual dimorphism in the fore and hindwings of seven hawkmoth species. The shape variables produced were then subjected to a discriminant analysis. The allometric effects were measured with a simple regression between the canonical variables and the centroid size. We also used the normalized residuals to assess the nonallometric component of shape variation with a t-test. The deformations in wing shape between sexes per species were assessed with a regression between the nonreduced shape variables and the residuals. We found sexual dimorphism in both wings in all analyzed species, and that the allometric effects were responsible for much of the wing shape variation between the sexes. However, when we removed the size effects, we observed shape sexual dimorphism. It is very common for females to be larger than males in Lepidoptera, so it is expected that the shape of structures such as wings suffers deformations in order to preserve their function. However, sources of variation other than allometry could be a reflection of different reproductive flight behavior (long flights in search for sexual mates in males, and flight in search for host plants in females).     

The effect of the density and physical properties of grass stems on the foraging behaviour and instantaneous intake rate by cattle grazing an artificial reproductive tropical sward

In reproductive swards, stems appear to act as vertical or horizontal barriers to bite formation, influencing instantaneous intake rate (IIR). The hypothesis was tested that the stems’ barrier effect is determined by the physical properties and density of stems. Artificial microswards, consisting of 20‐cm leaves and 15‐cm stems of Panicum maximum, were offered to three steers (362 kg) in a factorial combination of three stem densities (0, 100 and 400 stems m^?2) and two levels of stem tensile resistance [low (LTRS) and high tensile‐resisting stems (HTRS)]. LTRS were not a barrier to defoliation and did not affect bite depth and bite mass. HTRS acted as both a horizontal barrier and a vertical barrier depressing bite depth (13·4, 13·6 and 5·1 cm for 0, 100 and 400 stems m^?2, respectively), bite area (89·3, 50·8 and 47·6 cm² for 0, 100 and 400 stems m^?2, respectively), bite mass (0·51, 0·29 and 0·11 g for 0, 100 and 400 stems m^?2, respectively) and IIR (23·8, 10·5 and 3·6 g sec^?2 for 0, 100 and 400 stems m^?2, respectively). The results confirmed the importance of the density and physical properties of stems as determinants of the stems’ barrier effect on bite dimensions and IIR.     

A multi‐attribute trade‐off approach for advancing the management of marine wildlife tourism: a quantitative assessment of heterogeneous visitor preferences

• 1. Wildlife tourism can be prone to unmitigated development to promote visitor satisfaction that is all too often progressed at the cost of ecological integrity. A manager is thus faced with the dual task of enhancing the tourist experience and protecting the wildlife species. Accordingly, this mandate requires research into how tourists would respond to proposed wildlife‐management plans.
• 2. This study examines the heterogeneity of tourist preferences for wildlife management at a stingray‐feeding attraction in the Cayman Islands, using a latent class stated preference choice model. A sample of visitors to Stingray City Sandbar (SCS) evaluated hypothetical wildlife viewing experiences in a discrete choice experiment. Its scenarios were characterized by seven attributes such as animal‐feeding and handling rules, ecological outcomes, social crowding, and management cost (defined as a conservation access fee).
• 3. The latent class segmentation identified two groups in the population: approximately 68% preferred the implementation of fairly strict management rules, while the other 32% valued more the maintenance of status quo with its intensive human — wildlife interactions. Despite the differences between the ‘pro‐management’ and the ‘pro‐current’ segments, both exhibited a preference for the continuation of feeding and handling the stingrays (albeit at different levels of intensity) suggesting that one effective way to implement any management actions is to alter the promotional and marketing strategies for SCS. Other survey questions on trip experience, conservation values, and socio‐demographics were used to define these classes further, with the main distinguishing trait being the level of concern for potential impacts occurring at SCS. The discrepancies between the two segments became most obvious when calculating their respective market shares of support for alternative management strategies.
• 4. This approach to determining visitor preferences can help explain how the various segments will be affected by management options, and therefore can provide the basis for developing feasible strategies that will assist wildlife managers in maximizing tourist satisfaction while achieving wildlife‐protection goals.

Copyright © 2008 John Wiley & Sons, Ltd.     

自适应加权算子结合主曲线提取玉米叶片点云骨架

为从玉米叶片点云数据（尤其是缺失点云数据）中准确提取骨架特征,该研究设计了一种考虑玉米叶片形状结构和数据完整性的自适应加权算子来计算玉米叶片点云的骨架约束点集,并引入主曲线对骨架约束点集进行拟合得到优化的玉米叶片点云骨架。首先使用K均值聚类将玉米叶片分为若干变化较为平缓的部分;然后通过改进的距离场方法提取点云的截面相关点集;再利用设计的包括空间距离、法向差异和点云完整性的自适应加权算子,提取骨架约束点集;最后计算骨架约束点集的主曲线得到最终的玉米叶片点云骨架。通过对30个具有典型形状特征的玉米叶片点云数据的测试结果表明,本文方法所提取的骨架能较好地反映玉米叶片的三维形状结构,利用所提取骨架计算的叶长与实测叶长的平均绝对百分比误差（Mean Absolute Percent Error,MAPE）为2.10%,均方根误差（Root Mean Square Error,RMSE）为2.21 cm,标准化均方根误差（Normalized Root Mean Square Error,NRMSE）为2.89%。该方法可实现玉米叶片点云骨架的自动提取,对缺失的点云数据具有较好的鲁棒性,无需后期手动调整,能够为表型大数据处理、自动化表型解析等提供技术支持。     

基于非均匀性和分形维数的黄土优先流特征定量分析

该文以陕西泾阳南塬边坡黄土为例开展示踪剂试验,通过改进的优先流入渗深度和入渗量非均匀性系数,研究黄土优先流的入渗量、入渗深度、含水率、孔隙率、分形等参数的相互关系及其内在规律。结果表明:1)入渗量越大,优先流入渗深度的非均匀性越明显;2)初始含水率越高,优先流发育程度越低,而湿润锋迹线的分形维数越小;3)黄土孔隙率越大,优先流入渗深度的非均匀性越明显,且入渗深度值波动范围也相对较大;4)同一类型的黄土,其试验尺度大小对湿润锋迹线的分形维数没有明显影响;5)在0.5倍黄土优先流最大入渗深度范围内,分形特征值越大,优先流非均匀程度越强,优先流越发育;6)在没有明显优先流渗流通道情况下,90 mm地表灌溉水量,其最大入渗深度不超过120 cm。考虑正常蒸发和没有裂缝的前提下,地表灌溉水并不容易直接导致地下水位上升。由此推断,优先流在地表水向地下水转换过程中发挥着重要作用。同时,优先流对黄土滑坡的影响不容忽视。研究可为深入揭示黄土优先流渗流特征与黄土优先流滑坡的内在联系提供依据。     

泌蜡、造脾与繁蜂

目的为了解随着巢脾使用时间的增加,巢脾结构的变化对中华蜜蜂蜂群生长及工蜂形态特征的影响。方法以云贵高原中华蜜蜂(生态型之一)连续使用不同时间(20 d、半年、1年和2年)的巢脾及巢脾培育的出房工蜂为试验材料,观测巢脾颜色和结构、蜂群生长及工蜂形态特征等指标。结果随着使用时间的增加,巢脾颜色逐渐变深,子脾区域巢脾厚度和巢房深度逐渐增加,但巢房内围边长、内围直径和容积逐渐减小。巢脾结构的变化导致培育的蜂子数量、子脾面积和出房工蜂形态指标均极显著减小(P<0.01)。结论中华蜜蜂蜂群生长状况及工蜂形态特征均受巢脾的使用时间及其结构变化影响,新巢脾对蜂群培育蜂子效果较好。因此,在科学饲养中华蜜蜂时,蜂农应及时促蜂造脾,并在巢脾使用半年后进行淘汰换新,这对制定合理的中华蜜蜂饲养管理方案和提高蜂群生产性能有重要的意义。     

Morphometric discrimination of wild from farmed Dybowski’s frog (Rana dybowskii) based on hindlimb length

Commercial farming of anuran species that are declining in the wild raises a need to discriminate wild from farmed frogs.We hypothesized wild frogs might have extended hindlimbs due to greater frequency or intensity of jumping relative to farmed frogs,highlighting a morphometric approach to discrimination of wild from farmed frogs using hindlimb length.In the present study,Dybowski’s frog(Rana dybowskii) was used to test this hypothesis.We measured body mass(Mb) and hindlimb length(Lh) of 2-year old farmed frogs and wild frogs aged 2 to 5 years.Dybowski’s frog demonstrated significant dimorphism in Mb and Lh.Mb was significantly greater among farmed 2-year old frogs in both sexes(p=0.000),while only among females was Lh significantly greater for wild frogs(p=0.000).Lh/Mb was used as an index for origin discrimination to eliminate the influence of Mb due to variation of husbandry conditions among farms.Mean Lh/Mb for farmed frogs was significantly lower than for wild frogs(p=0.000) in the 2-year old age class.Discrimination correctly classified 84.4% of farmed and 96.3% of wild male frogs.Among females,92.9% of farmed frogs and 90.1% wild frogs were correctly classified.The overall correctness of classification was 92.1% and 90.8% for males and females,respectively.However,Lh/Mb revealed variation with age,resulting in reduced discriminative power for frogs ≥3 years old.We introduced a coefficient Ce to adjust the Lh/Mb of frogs ≥3 years to the level equivalent to 2-year frogs.The adjustment achieved 89.5% for overall correctness of origin for wild males and 92.4% for wild females ≥3 years old.These results show that Lh/Mb is an effective index to discriminate wild from farmed Dybowski’s frog.Since the physical demands of jumping are common among anurans,this index is also potentially applicable to other anuran species.