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1.
The trunk canal of fishes is contained within a series of lateral line (LL) scales. To categorise LL scale structural types, and determine their distribution, an analysis of original data was undertaken using light and scanning electron microscopy in combination with a literature survey from over 1,000 species representative of most orders of bony fishes. Our categorisation of LL scales is based on the relationship between the tube, or ossified trunk canal segment, and associated scale. Tubular‐Scalar LL scales consist of a distinguishable tube and elasmoid scale in scale pockets. Four types occur only in species with elasmoid scales. Integrated LL scales do not develop in scale pockets, and their tube is enclosed or extended by a non‐elasmoid scale or spines. Integrated 1 and 2 LL scales co‐occur with ganoid and calcidermoid scales, and Integrated 3 LL scales occur when common scales are absent or elasmoid. Tubular LL scales are tubes only, occurring mainly in scaleless species or with calcidermoid and elasmoid scales. Non‐Tubular LL scales are composed only of a scale, co‐occurring mainly with cycloid scales. There is consistency of LL scale type in many orders, families and genera and the presence of different types within taxa can be meaningful.  相似文献   

2.
Scale in macroecology   总被引:4,自引:0,他引:4  
The past 15 years have seen the development of macroecology as a respectable discipline within the biological sciences. Initial concerns about the utility of a large‐scale approach to ecology have been quietened, if not eliminated, but other arguments about spatial scale in ecology have arisen to take their place. The situation has moved from the absolute advocacy of small‐scale over large‐scale studies to an advocacy of some large scales in preference to others. Here, we argue that there is no general sense in which one scale of study (either in terms of spatial extent or sampling resolution) is better than any other. As long as there are sensible reasons for using the scale chosen, studies at all scales have the potential to inform about the structure and function of the ecological systems that clothe this planet.  相似文献   

3.
The ultrastructure of the dorsal forewing vestiture in exemplars of all family group taxa of non‐ditrysian Lepidoptera is examined, and the evolutionary implications at family level and above are discussed. Wing‐scale terminology is reviewed. Three different types of bilayer wing‐scale covering are recognized; only a few groups have a single‐layer wing‐scale covering. The general scale arrangement is random, but a few taxa have clustered scale arrangements and scattered heteroneurans have scales arranged in transverse rows. Cross ribs are present in all taxa, but only as vestiges in eriocraniid cover scales. Ridge dimorphism is widespread in Neolepidoptera. Surprisingly, ridges and cross ribs on the adwing scale surface are of general occurrence in Neopseustidae and Hepialidae, and are even found on parts of the ground scales of many other Neolepidoptera. Morphological evidence strongly indicates that the fused wing‐scale types found in non‐Coelolepidan Lepidoptera and Neolepidoptera are independently evolved, as evidenced from the presence of vestigial perforations. Absence of perforations is not infallible evidence that a scale is solid. Microtrichia are independently reduced in a number of taxa and probably re‐evolved in at least higher nepticulids. Wing vestiture and scale characters indicate that Tischerioidea may be the sister group of Ditrysia.  相似文献   

4.
The most widely used scale for assessing food liking or disliking is the 9‐pt hedonic scale. Unfortunately, this affective scale suffers from problems related to unequal scale intervals and the underuse of end categories, which results in a reduced ability to differentiate among extremely well liked or extremely disliked foods. Magnitude estimation avoids these problems while enabling ratio statements to be made about the data. However, it does not provide absolute ratings of liking/disliking and can be difficult for some consumers to use. We report here on the development of a labeled affective magnitude scale (LAM) scale that has advantages over both the 9‐pt hedonic scale and magnitude estimation. Forty‐four semantic labels were scaled for their affective meaning by subjects using modulus‐free magnitude estimation. The geometric mean magnitude estimates obtained for each semantic label were used to construct a series of labeled affective magnitude scales by spacing the labels along a visual analogue scale according to their obtained semantic values. Reliability and sensitivity studies were conducted to assess the effects of alternative semantic and numeric labels. The results of these studies led to the choice of a scale format that uses verbal labels that are consistent with the 9‐pt hedonic scale. The labeled affective magnitude (LAM) scale was compared to the hedonic scale and magnitude estimation in several food preference and acceptability tests. The LAM was shown to have equal reliability and sensitivity to the hedonic scale, provided somewhat greater discrimination among highly liked foods, and resulted in data that were similar to magnitude estimation in terms of the obtained ratios among rated stimuli. The LAM scale was also judged by consumers to be as easy to use as the 9‐pt hedonic scale and significantly less difficult than magnitude estimation.  相似文献   

5.
Although the α-glucosidase inhibitor miglitol (MG) has been reported to have anorexigenic effects, the mechanism remains to be elucidated. The objective of this study was to explore the effects of MG on appetite in relation to concomitant changes in postprandial gut hormone levels. This randomized open-label crossover study included 20 healthy volunteers. The effects of 50 mg MG on glucagon-like peptide-1 (GLP-1), peptide YY (PYY), and ghrelin levels were assessed in conjunction with a simultaneous determination of appetite scores using visual analogue scales (VAS) over 3 h after the ingestion of a 592 kcal test cookie. Additionally, the gastric emptying rate (GER) was measured using breath 13CO? appearance in 10 subjects. 12 subjects were administered 50 mg MG thrice a day for 1 week, and alterations of the gut hormone levels and the VAS scores for appetite were evaluated. MG pre-administration resulted in a significant enhancement of GLP-1 and PYY responses induced by the cookie ingestion. Following MG administration, ghrelin level declined at 1 h, with a persistent suppression during the postprandial phase in contrast to the restoration to the basal level without MG. Furthermore, MG pre-administration suppressed appetite and maintained satiety evaluated using a VAS rating with concomitant inhibition of GER after cookie ingestion. One-week administration of MG did not influence either gut hormone levels before a meal or VAS rating during a whole day. These observations suggest that MG exerts an anorexigenic effects with concomitant alterations of gut hormone secretions and gastric emptying after meal ingestion.  相似文献   

6.
In a context of scarce financial and human resources, the allocation of conservation efforts needs to be optimized. Our analysis attempts to draw conclusions on the integration of regional and local conservation assessments, specifically, with regard to the acquisition of fine‐scale data to complement the regional assessment. This study undertaken in Réunion Island (Indian Ocean) assessed how biodiversity surrogates targeted at a regional scale represented other biodiversity surrogates at a local scale. Biodiversity surrogates at both scales consisted of species, habitats and processes. Habitats and processes at regional scale were defined using a coarser scale of thematic resolution than at local scale. The surrogacy was tested in terms of incidental representation of local‐scale features in the regional assessments, and correlation of irreplaceability values between scales. Near‐minimum sets and irreplaceability values were generated using MARXAN software. Our results revealed that conservation targets for processes at local scale were never met incidentally, while threatened species and fragmented habitats were also usually under‐represented. More specifically, requiring only 12% of the local planning domain, the application of species as surrogates at regional scale was the least effective option at representing biodiversity features at local scale. In contrast, habitats at a coarse scale of thematic resolution achieved a significant proportion of conservation targets incidentally (67%) and their irreplaceability values were well correlated with the irreplaceability values of surrogates at local scale. The results highlighted that all three types of biodiversity surrogates are complementary for assessing overall biodiversity. Because of the cost of data acquisition, we recommended that the most efficient strategy to develop nested regional/local conservation plans is to apply habitats and processes at a coarse scale of thematic resolution at regional scale, and threatened species and degraded habitats at local scale, with their fine‐scale mapping limited to highly transformed areas.  相似文献   

7.
A special type of ordinal scale comprising a number of intervals of known numeric ranges can be used when estimating severity of a plant disease. The interval ranges are most often based on the percent area with symptoms [e.g. the Horsfall–Barratt (H–B) scale]. Studies in plant pathology and plant breeding often use this type of ordinal scale. The disease severity is estimated by a rater as a value on the scale and has been used to determine a disease severity index (DSI) on a percentage basis, where DSI (%) = [sum (class frequency × score of rating class)]/[(total number of plants) × (maximal disease index)] × 100. However, very few studies have investigated the effects of different scales on accuracy of the DSI. Therefore, the objectives of this study were to investigate the process of calculating a DSI on a percentage basis from ordinal scale data, and to use simulation approaches to explore the effect of using different methods for calculation of the interval range and the nature of the ordinal scales used on the DSI estimates (%). We found that the DSI is particularly prone to overestimation when using the above formula if the midpoint values of the rating class are not considered. Moreover, the results of the simulation studies show that, if rater estimates are unbiased, compared with other methods tested in this study, the most accurate method for estimation of a DSI is to use the midpoint of the severity range for each class with an amended 10% ordinal scale (an ordinal scale based on a 10% linear scale emphasising severities ≤50% disease, with additional grades at low severities). As for biased conditions, the accuracy for calculating DSI estimates (%) will depend mainly on the degree and direction of the rater bias relative to the actual mean value.  相似文献   

8.
Ornithoptera birdwing butterflies have blue, green, or orange iridescent scales in different species or subspecies. To understand the species‐ or subspecies‐dependent scale color differences, we performed comparative morphometric analyses of iridescent scales from three closely related taxa: O. priamus priamus (green), O. priamus urvillianus (blue), and O. croesus (orange). The three types of Ornithoptera wings exhibited reversible color changes to longer wavelengths with different kinetics upon immersion in methanol, suggesting that their color differences are at least partly based on differences in the size of air cavities made by nanostructures. Cover scales of all three color types were visually semi‐transparent glass scales that exhibited color when placed on a dark background. The dorsoventral differences in coloration were observed in single scales, suggesting the optical importance of scale surfaces. Scanning electron microscopy of cover scales in cross section revealed that all color types exhibited finely sculpted tapered ridges and thick, irregular basal multilayers containing tandemly clustered granular objects and air cavities. Scale thickness, ridge height, and multilayer thickness were significantly different among the three color types, and granular object size was significantly different between orange scales and blue and green scales. We conclude that each of the three taxa of Ornithoptera butterflies possesses unique quantitative size values on tapered ridges and irregular multilayers with granular objects and air cavities to express unique structural color. These species‐ or subspecies‐dependent structural colors might have evolved via quantitative shifts in these microarchitectural traits rather than via changes in the basic developmental or architectural plan for color expression.  相似文献   

9.
景观生态学研究的就是某一空间尺度范围内的景观格局与生态过程。因为景观格局与生态过程中存在的尺度多样性 ,导致尺度成为理解景观格局和生态过程相互作用的关键 ,其已经成为景观生态学的一个重要概念 ,但是由于理论和方法的限制 ,对景观生态学的尺度研究还不够 ,特别是景观格局综合性指标在不同幅度上的变化特征和效应。在 GIS与 RS技术支持下 ,采用基准分辨率为 5 m的 SPOT遥感图像作为数据源 ,对不同幅度下的城市景观多样性的空间分布格局进行了分析 ,并进一步利用半变异函数对其空间异质性进行定量描述。结论揭示 :随着空间尺度的增加 ,景观多样性程度也不断增加 ,另外多样性的空间分布格局也具有显著变化 ,由于受城市发展历史和目前城市扩展方向的影响 ,多样性在总体上是不平衡的 ,尺度越大 ,不平衡越明显 ;不同尺度下景观多样性空间格局的变化 ,与城市景观的特点和城市景观的功能息息相关 ,不过其受经济效益和社会文化效益的影响更大 ;随着尺度增加由于掩盖了更小尺度上的变异 ,导致块金效应增强 ,空间自相关部分对系统总的变异则明显下降 ;景观多样性具有尺度依赖性 ,可以说景观多样性也是尺度的函数 ,在不同的尺度上 ,结果差异显著 ,所以在景观生态学的研究中绝对不能忽略尺度对格局的影响  相似文献   

10.
A comparative study comprising scale morphology and squamation of Saurida tumbil was conducted to identify the most useful scale and squamation characters within the different body regions and length groups and to clarify their significance for future systematic studies. The presence of the caudal pores is documented for the first time in teleosts. In addition, the presence of crenae and spines formed by posterior orientation and projection of circuli is recorded for the first time in a member of the Synodontidae. Scales of S. tumbil show some characters that are either never seen or they are exceedingly rare in scales of other teleosts. These are: two types of scalar denticles, denticles in the inter-circular area, and twin or Siamese scales. Several other scale characters have shown a consistent variation in different body regions and in fishes from different length groups. These are: focus position; bilobate rostral field edge; presence of three radii; long, narrow and separated crenae; papillae-form, crowded scalar denticles with posterior directed spines; the number of scale rows between anterior end of the dorsal fin and the lateral line.  相似文献   

11.
The assessment of cultural ecosystem services, in our case landscape aesthetics, is the most commonly investigated but least formalized issue in the scope of the ecosystem services concept. In contrast to ecological or economic aspects, the assessment of aesthetics cannot easily be based on quantitative information. Therefore, two different methodological approaches that assess landscape aesthetics either from an objective or a subjective point of view have been established in the past.This article presents in its first part an objective, landscape metrics-based assessment approach. We defined naturalness and landscape diversity as assessment criteria and selected Shannon's Diversity Index (SHDI), Shape Index (SHAPE) and Patch Density (PD) as indicators. We tested our approach for a set of nine different landscape types in a model region in Saxony, Germany.For validating the developed methodology, we carried out a survey with 153 participants in order to investigate their subjective preferences for the different landscape types. These preferences had to be expressed by rating the landscape types on a scale from 1 (very ugly) to 5 (very beautiful). The study was based on three different data sets, namely photographs of the landscape types, satellite images, and land cover maps.Statistical tests were applied (a) to investigate the impact of personal factors on the ratings, (b) to detect whether abstraction levels are suitable for preference studies, and (c) to compare the results of the objective approach (landscape metrics) and the subjective approach (visual assessment). Personal factors did not influence the visual assessment results significantly. We found the highest correlation of the landscape metrics-based assessment with the visual assessment results of the photographs. We conclude that the three landscape metrics might be applied to the monitoring of landscape aesthetics. An extended study with more participants might be useful to further investigate the reliability of our findings.  相似文献   

12.
Hypotheses about phylogenetic relationships among species allow inferences about the mechanisms that affect species coexistence. Nevertheless, most studies assume that phylogenetic patterns identified are stable over time. We used data on monthly samples of fish from a single lake over 10 years to show that the structure in phylogenetic assemblages varies over time and conclusions depend heavily on the time scale investigated. The data set was organized in guild structures and temporal scales (grouped at three temporal scales). Phylogenetic distance was measured as the mean pairwise distances (MPD) and as mean nearest‐neighbor distance (MNTD). Both distances were based on counts of nodes. We compared the observed values of MPD and MNTD with values that were generated randomly using null model independent swap. A serial runs test was used to assess the temporal independence of indices over time. The phylogenetic pattern in the whole assemblage and the functional groups varied widely over time. Conclusions about phylogenetic clustering or dispersion depended on the temporal scales. Conclusions about the frequency with which biotic processes and environmental filters affect the local assembly do not depend only on taxonomic grouping and spatial scales. While these analyzes allow the assertion that all proposed patterns apply to the fish assemblages in the floodplain, the assessment of the relative importance of these processes, and how they vary depending on the temporal scale and functional group studied, cannot be determined with the effort commonly used. It appears that, at least in the system that we studied, the assemblages are forming and breaking continuously, resulting in various phylogeny‐related structures that makes summarizing difficult.  相似文献   

13.
The relative importance of environmental and spatial drivers of animal diversity varies across scales, but identifying these scales can be difficult if a sampling design does not match the scale of the target organisms' interaction with their habitat. In this study, we quantify and compare the effects of environmental variation and spatial proximity on ground‐dwelling spider assemblages sampled from three distinct microhabitat types (open grassland, logs, trees) that recur across structurally heterogeneous grassy woodlands. We used model selection and multivariate procedures to compare the effects of different environmental attributes and spatial proximity on spider assemblages at each microhabitat type. We found that species richness and assemblage composition differed among microhabitat types. Bare ground cover had a negative effect on spider richness under trees, but a positive effect on spider richness in open grassland. Turnover in spider assemblages from open grassland was correlated with environmental distance, but not geographic distance. By contrast, turnover in spiders at logs and trees was correlated with geographic distance, but not environmental distance. Our study suggests that spider assemblages from widespread and connected open grassland habitat were more affected by environmental than spatial gradients, whereas spiders at log and tree habitats were more affected by spatial distance among these discrete but recurring microhabitats. Deliberate selection and sampling of small‐scale habitat features can provide robust information about the drivers of arthropod diversity and turnover in landscapes.  相似文献   

14.
Although the efficacy and safety of the topical anesthetic EMLA cream (lidocaine-prilocaine) have been studied extensively in children and adults, no published studies have focused on geriatric patients (>/=65 years of age). The objective of this study was to compare the efficacy and safety of EMLA in geriatric versus nongeriatric adults. A pooled analysis was made from original data of six studies of EMLA cream for split-skin grafting. The studies selected had a sufficient number of geriatric and nongeriatric adults and a uniform, standardized pain stimulus (split-skin grafting), pain rating (visual analogue scale, verbal rating scale) and adverse event recording. A total of 182 geriatric patients (82 aged 65 to 74 years; 100 aged 75 to 96 years) and 221 nongeriatric EMLA-treated patients were evaluated. There was no difference in the efficacy of EMLA between geriatric and nongeriatric adults who underwent similar onset and duration of anesthesia. EMLA cream 1.5 g/10 cm2 applied for 2 to 5 hours had a similar anesthetic effect in both age groups. A dose of 3 g/10 cm2 gave no further benefit. In a geriatric population, EMLA cream provided effective cutaneous anesthesia for the cutting of split-skin grafts to the same extent as did infiltrated lidocaine. Adverse event frequency and severity were similar in geriatric and nongeriatric patients. Transient application site pallor, redness, and edema were the most frequent adverse events. Topical anesthesia with EMLA cream for split-skin grafting is as safe and effective in geriatric as in nongeriatric adults.  相似文献   

15.
牙鲆、大黄鱼和小黄鱼不同部位鳞片类型的比较   总被引:1,自引:0,他引:1  
王晶  高磊  鲍宝龙 《动物学杂志》2017,52(5):850-856
真骨鱼类的骨鳞有圆鳞和栉鳞两种类型,观察了大黄鱼(Larimichthys crocea)和小黄鱼(Pseudosciaena polyactis)成体的鳞片类型,发现同一个体同时存在圆鳞和栉鳞,有典型的圆鳞和栉鳞结构,也有两者的过渡型形态。而对100日龄和成体牙鲆(Paralichthys olivaceus)不同部位鳞片类型的观察发现,100日龄牙鲆眼侧存在圆鳞向栉鳞过渡的Ⅲ型鳞片、Ⅳ型初始栉鳞和Ⅴ型典型栉鳞,而成体牙鲆有眼侧仅覆盖Ⅴ型典型栉鳞,推测栉鳞和圆鳞可能存在发育上的联系。通过统计大黄鱼和小黄鱼不同部位的圆鳞和栉鳞数量,发现二者体表栉鳞数量均为从头部到尾部依次减少,而背部与腹部之间没有明显差异。  相似文献   

16.
Parrotfishes are considered to have a major influence on coral reef ecosystems through grazing the benthic biota and are also primary fishery targets in the Indo‐Pacific. Consequently, the impact of human exploitation on parrotfish communities is of prime interest. As anthropogenic and environmental factors interact across spatial scales, sampling programs designed to disentangle these are required by both ecologists and resource managers. We present a multi‐scale examination of patterns in parrotfish assemblage structure, size distribution and diversity across eight oceanic islands of Micronesia. Results indicate that correlates of assemblage structure are scale‐dependent; biogeographic distributions of species and island geomorphology hierarchically influenced community patterns across islands whereas biophysical features and anthropogenic pressure influenced community assemblage structure at the within‐island scale. Species richness and phylogenetic diversity increased with greater broad‐scale habitat diversity associated with different island geomorphologies. However, within‐island patterns of abundance and biomass varied in response to biophysical factors and levels of human influence unique to particular islands. While the effect of fishing activities on community composition and phylogenetic diversity was obscured across island types, fishing pressure was the primary correlate of mean parrotfish length at all spatial scales. Despite widespread fishery‐induced pressure on Pacific coral reefs, the structuring of parrotfish communities at broad spatial scales remains a story largely dependent on habitat. Thus, we propose better incorporation of scale‐dependent habitat effects in future assessments of overexploitation on reef fish assemblages. However, strong community‐level responses within islands necessitate an improved understanding of the phylogenetic and functional consequences of altering community structure.  相似文献   

17.
Predicting population colonisations requires understanding how spatio‐temporal changes in density affect dispersal. Density can inform on fitness prospects, acting as a cue for either habitat quality, or competition over resources. However, when escaping competition, high local density should only increase emigration if lower‐density patches are available elsewhere. Few empirical studies on dispersal have considered the effects of density at the local and landscape scale simultaneously. To explore this, we analyze 5 years of individual‐based data from an experimental introduction of wild guppies Poecilia reticulata. Natal dispersal showed a decrease in local density dependence as density at the landscape level increased. Landscape density did not affect dispersal among adults, but local density‐dependent dispersal switched from negative (conspecific attraction) to positive (conspecific avoidance), as the colonisation progressed. This study demonstrates that densities at various scales interact to determine dispersal, and suggests that dispersal trade‐offs differ across life stages.  相似文献   

18.
动物生境选择研究中的时空尺度   总被引:17,自引:0,他引:17  
张明海  李言阔 《兽类学报》2005,25(4):395-401
尺度研究已成为生态学上的一个重要概念和研究热点,但是在动物生境选择的研究中尚未引起足够的重视。动物的生境选择包括多层次的判别和一系列等级序位,在各个尺度和水平上具有不同的特征和机制,受到时空尺度的严格限定。繁殖期的时间限制、社群压力、环境变化、动物生理需求的变化决定了动物生境选择的时间制约性;而生境资源的斑块化分布、功能生境之间的相互作用决定了动物生境选择的空间制约性。研究者对时间和空间尺度的选取与应用会直接影响到生境选择研究结果的科学性和实效性。本文从动物生境选择的时空制约性出发,分析了生境选择研究中时间尺度的重要性,叙述了国内外生境选择研究中常见的研究尺度,强调了多尺度研究和长期生态研究的必要性,尺度的选择应该成为生境选择研究的起点和基础。  相似文献   

19.
Vegetation maps are critical biodiversity planning instruments, but the classification of vegetation for mapping can be strongly biased by survey design. Standardization of survey design across different vegetation types is therefore increasingly recommended for vegetation mapping programs. However, some vegetation types have complex small‐scale vegetation patterns that are important in characterizing these vegetation types, and standard designs will often not capture these patterns. The objective of this paper was to investigate the magnitude of potential map bias that results from survey design standardization and recommend approaches to deal with this bias. We surveyed upland swamps of the Greater Blue Mountains World Heritage Area Australia using two contrasting survey designs, including the standard 400 m2 single quadrat design recommended and used by authorities. We then derived a classification for these swamps and tested the effect of survey design on this classification, species richness and the type of species detected (obligate or facultative swamp species). Species richness and species type were not significantly different among survey techniques. However, more than 40% of swamps clustered differently among survey designs. Thus, one of the 10 derived communities (which is floristically consistent with a previously mapped endangered community) was indistinct, and some individual swamps misclassified using the standard survey design. An effect of landscape position on swamp floristic patterns and a significant trend for high similarity scores among swamps surveyed with multiple small quadrats compared to the standard survey design was also determined. Australian upland swamps are classified at the global scale as shrub‐dominated wetlands, and complex floristic patterns have been recorded in shrub‐dominated wetlands in both northern and southern hemispheres. We therefore advocate either multiple survey designs or different survey standards for upland swamp communities and other vegetation types that have complex floristic patterns at small scales.  相似文献   

20.
Four types of rating scales, nine-point category scales, line marking, magnitude estimation, and a hybrid of the category and line scale, were employed to assess visual, tactile and olfactory characteristics of products by consumers. The scales were compared for their ability to discriminate differences among products, for variability, for reliability, and for ease of use. All methods were able to generate highly significant differences among products. However, a modest advantage for category scales was observed in almost all comparisons.  相似文献   

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