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1.
Understanding bird migration and dispersal is important to inform full life-cycle conservation planning. Stable hydrogen isotope ratios from feathers (δ2Hf) can be linked to amount-weighted long-term, growing season precipitation δ2H (δ2Hp) surfaces to create δ2Hf isoscapes for assignment to molt origin. However, transfer functions linking δ2Hp with δ2Hf are influenced by physiological and environmental processes. A better understanding of the causes and consequences of variation in δ2Hf values among individuals and species will improve the predictive ability of geographic assignment tests. We tested for effects of species, land cover, forage substrate, nest substrate, diet composition, body mass, sex, and phylogenetic relatedness on δ2Hf from individuals at least two years old of 21 songbird species captured during the same breeding season at a site in northeastern Alberta, Canada. For four species, we also tested for a year × species interaction effect on δ2Hf. A model including species as single predictor received the most support (AIC weight = 0.74) in explaining variation in δ2Hf. A species-specific variance parameter was part of all best-ranked models, suggesting variation in δ2Hf was not consistent among species. The second best-ranked model included a forage substrate × diet interaction term (AIC weight = 0.16). There was a significant year × species interaction effect on δ2Hf suggesting that interspecific differences in δ2Hf can differ among years. Our results suggest that within- and among-year interspecific variation in δ2Hf is the most important source of variance typically not being explicitly quantified in geographic assignment tests using non-specific transfer functions to convert δ2Hp into δ2Hf. However, this source of variation is consistent with the range of variation from the transfer functions most commonly being propagated in assignment tests of geographic origins for passerines breeding in North America.  相似文献   

2.
The spatial pattern of the small fish community was studied seasonally in 1996 in the Biandantang Lake. Based on plant cover, the lake was divided into five habitats, arranged in the order by plant structure complexity from complex to simple: Vallisneria spiralis habitat (V habitat), Vallisneria spiralis–Myriophyllum spicatum habitat (V–M habitat), Myriophyllum spicatum habitat (M habitat), Nelunbo nucefera habitat (N habitat), and no vegetation habitat (NV habitat). A modified popnet was used for quantitative sampling of small fishes. A total of 16 fish species were collected; Hypseleotris swinhonis, Ctenogobius giurinus, Pseudorasbora parva, Carassius auratus and Paracheilognathus imberis were the five numerically dominant species. In both summer and autumn, the total density of small fishes was about 10indm–2. Generally, Ctenogobius giurinus, a sedatory, benthic fish, was distributed more or less evenly among the five habitats, while the other four species had lower densities in the N habitat and NV habitat, which had the simplest structures. The distribution of the small fish species showed seasonal variations. In winter, most species concentrated in the V habitat, which had the most complex structure. In spring, the fish had low densities in the N and NV habitat, and were more or less evenly distributed in the other habitats. In summer, the fish had a low density in the NV habitat, and were evenly distributed in the other habitats. In autumn, the fish had higher densities in the V–M and M habitats than in the others. Generally, spatial overlaps between the dominant species were higher in winter than in the other seasons. It was suggested that the variations in the importance of predation risk and resource competition in habitat choice determined the seasonal changes of spatial patterns in the small fishes in the Biandantang Lake.  相似文献   

3.
Characterizing relationships between individual body size and trophic niche position is essential for understanding how population and food-web dynamics are mediated by size-dependent trophic interactions. However, whether (and how) intraspecific size-trophic relationships (i.e., trophic ontogeny pattern at the population level) vary with time remains poorly understood. Using archival specimens of a freshwater predatory fish Gymnogobius isaza (Tanaka 1916) from Lake Biwa, Japan, we assembled a long-term (>40 years) time-series of the size-dependence of trophic niche position by examining nitrogen stable isotope ratios (δ 15N) of the fish specimens. The size-dependence of trophic niche position was defined as the slope of the relationship between δ 15N and log body size. Our analyses showed that the slope was significantly positive in about 60% of years and null in other years, changing through time. This is the first quantitative (i.e., stable isotope) evidence of long-term variability in the size-trophic relationship in a predatory fish. This finding had implications for the fish trophic dynamics, despite that about 60% of the yearly values were not statistically different from the long-term average. We proposed hypotheses for the underlying mechanism of the time-varying size-trophic relationship.  相似文献   

4.

Aim

The purpose of this survey was to determine the cut-offs being used by Australian laboratories using their instrument’s Haemolysis Index (HI), whether these cut-offs vary, and at what level of haemolysis (or haemolysis index) did laboratories stop reporting one or more analytes. This was done in response to the large numbers of haemolysed samples reported in the RCPAQAP Key Incident Monitoring and Management System External Quality Assurance program (KIMMS EQA) and lack of information in the literature at the time regarding what to do once a haemolysed sample was identified. As it was known from discussions with laboratory personnel that different instruments reported their HI differently, we asked for the results to be provided in g/L free haemoglobin.

Method

An electronic survey was conducted with participants enrolled in the RCPA Quality Assurance Programs with a total of 68 laboratories responding to this survey. Some questions attracted a lower level of response.

Results

The responses showed a poor understanding of the relationship between HI units and haemoglobin concentration. There was wide variation in the way HI results were reported and thus comparing cut-off values for reporting specific analytes based on the HI was impossible to determine.

Conclusion

There is a need to harmonise the way laboratories report analytes in the presence of haemolysis. This would involve adopting a uniform definition of HI and a protocol for laboratories to confirm for themselves the level of HI at which each analyte is no longer reported, as this is method dependent and so will vary from laboratory to laboratory.  相似文献   

5.
The durations of the phases of the cell cycle were measured at different levels in the jejunal crypts of male Balb/c mice. A mean cell cycle time of 12.3 h was found for the whole crypt. In cell positions 1 and 2, the cell cycle time was 16.7 h, and this time steadily decreased to a value of between 10 and 11 h for cell positions above 11. It is concluded that basally situated crypt cells in the mouse are cycling relatively slowly, and that they form the functional stem cell pool for the crypt. These cells may also compose the potential stem cell pool which repopulates the crypt after death of proliferative cells.  相似文献   

6.
Summary Immunofluorescent labelling ofPhysarum microtubules with a new antibody specific for the 1-isotubulin has been compared with the labelling with an antibody specific for -isotubulins and an antibody with recognizes tubulin chains terminated by an aromatic amino-acid. In agreement with the known presence of only one -isotype in amoebae and several -isotypes in plasmodia, the immunofluorescence of the mitotic spindle was qualitatively identical, but lower in plasmodia than in amoebae. In all cases except one, there were no relative variations of immuno-fluorescence staining with the three antibodies, from metaphase to telophase, in spindles sampled. In plasmodia grown at optimal temperature, both during normal or perturbed mitosis, the immunostaining of the 1isotype decreased sharply after metaphase, while the staining obtained with the two other antibodies did not vary significantly. The immunologic determination of the relative amount of the 1-isotubulin in the tubulin pool and in isolated mitotic microtubules could not account for this observation.  相似文献   

7.
The nutritional state of animals is tightly linked to the ambient environment, and for northern ungulates the state strongly influences vital population demographics, such as pregnancy rates. Continuously growing tissues, such as hair, can be viewed as dietary records of animals over longer temporal scales. Using sequential data on nitrogen stable isotopes (δ15N) in muskox guard hairs from ten individuals in high arctic Northeast Greenland, we were able to reconstruct the dietary history of muskoxen over approximately 2.5 years with a high temporal resolution of app. 9 days. The dietary chronology included almost three full summer and winter periods. The diet showed strong intra- and inter-annual seasonality, and was significantly linked to changes in local environmental conditions (temperature and snow depth). The summer diets were highly similar across years, reflecting a graminoid-dominated diet. In contrast, winter diets were markedly different between years, a pattern apparently linked to snow conditions. Snow-rich winters had markedly higher δ15N values than snow-poor winters, indicating that muskoxen had limited access to forage, and relied more heavily on their body stores. Due to the close link between body stores and calf production in northern ungulates, the dietary winter signals could eventually serve as an indicator of calf production the following spring. Our study opens the field for further studies and longer chronologies to test such links. The method of sequential stable isotope analysis of guard hairs thus constitutes a promising candidate for population-level monitoring of animals in remote, arctic areas.  相似文献   

8.
The density of some species and total density of fishes have been estimated in river channel parts of the Ivankovo Reservoir in 2012–2015. The significant differences in the total abundance of fishes in 2012–2013 and 2014–2015 have been revealed. The increase in the number of tyulka (Clupeonella cultriventris (Nordmann, 1840)) in the Black and Azov seas in 2014–2015 was determined by their periodic fluctuations typical for any species with a short life cycle. Changes in the abundance of bream and silver bream in the reservoir pelagial relate to their vertical redistribution under the effect of environment factors.  相似文献   

9.

Objectives

Quantitative multidetector computed tomography (MDCT) as a potential biomarker is increasingly used for severity assessment of emphysema in chronic obstructive pulmonary disease (COPD). Aim of this study was to evaluate the user-independent measurement variability between five different fully-automatic densitometry software tools.

Material and Methods

MDCT and full-body plethysmography incl. forced expiratory volume in 1s and total lung capacity were available for 49 patients with advanced COPD (age = 64±9 years, forced expiratory volume in 1s = 31±6% predicted). Measurement variation regarding lung volume, emphysema volume, emphysema index, and mean lung density was evaluated for two scientific and three commercially available lung densitometry software tools designed to analyze MDCT from different scanner types.

Results

One scientific tool and one commercial tool failed to process most or all datasets, respectively, and were excluded. One scientific and another commercial tool analyzed 49, the remaining commercial tool 30 datasets. Lung volume, emphysema volume, emphysema index and mean lung density were significantly different amongst these three tools (p<0.001). Limits of agreement for lung volume were [−0.195, −0.052l], [−0.305, −0.131l], and [−0.123, −0.052l] with correlation coefficients of r = 1.00 each. Limits of agreement for emphysema index were [−6.2, 2.9%], [−27.0, 16.9%], and [−25.5, 18.8%], with r = 0.79 to 0.98. Correlation of lung volume with total lung capacity was good to excellent (r = 0.77 to 0.91, p<0.001), but segmented lung volume (6.7±1.3 – 6.8±1.3l) were significantly lower than total lung capacity (7.7±1.7l, p<0.001).

Conclusions

Technical incompatibilities hindered evaluation of two of five tools. The remaining three showed significant measurement variation for emphysema, hampering quantitative MDCT as a biomarker in COPD. Follow-up studies should currently use identical software, and standardization efforts should encompass software as well.  相似文献   

10.
Variation of seed -amylase inhibitors was investigated in 1 154 cultivated and 726 non-cultivated (wild and weedy) accessions of the common bean, Phaseolus vulgaris L. Four -amylase inhibitor types were recognized based on the inhibtion by seed extracts of the activities of porcine pancreatic -amylase and larval -amylase and larval -amylase of the Mexican bean weevil, Zabrotes subfasciatus Boheman. Of the 1 880 accessions examined most (1 734) were able to inhibit porcine pancreatic -amylase activity, but were inactive against the Z. subfasciatus larval -amylase; 41 inhibited only the larval -amylase activity, 52 inhibited the activities of the two -amylases, and 53 did not inhibit the activity of either of the -amylases. The four different inhibitor types were designated as AI-1, AI2, AI-3, and AI-0, respectively. These four inhibitor types were identified by the banding patterns of seed glycoproteins in the range of 14–20 kDa by using SDSpolyacrylamide gel electrophoresis. Additionally, four different banding patterns were recognized in accessions with AI-1, and were designated as AI-1a, 1b, 1c, and 1d. Two different patterns of the accessions lacking an -amylase inhibitory activity were identified and designated as AI-0a and AI-0b. The largest diversity for seed -amylase inhibitors was observed in non-cultivated accessions collected from Mexico where all eight inhibitor types were detected. The possible relationships between the variation of seed -amylase inhibitors and bruchid resistance are discussed.  相似文献   

11.
Summary The varied appearance of so-called structured granules in vegetative cells and akinetes of Anabaena sp. is dependent upon the length of primary glutaraldehyde fixation, the type and duration of secondary fixation, and the temperature during both fixations as well as possible changes under electron bombardment. The image produced may be one of an open hole, an area of low to medium electron opacity or that of a dense structured body and may include all intergradations. These structured granules represent the cyanophycin granules of light microscopy. Various cytochemical tests did not establish their chemical composition.  相似文献   

12.
13.
Empirical studies into obligate pollination mutualisms which elucidate the variation in reproductive performance of shrinking populations within human-altered environments are rare. This study focuses on the obligate pollination mutualism between Trollius europaeus (Ranunculaceae) and fly species of the genus Chiastocheta which act both as the plant’s main pollinators and as predators in that their larvae eat a fraction of the developing seeds. The study area is situated in the lowlands of north-east Germany. Many populations of T. europaeus have become comparatively small and scattered in this region as a consequence of agricultural land use intensification. We studied the plant’s reproductive fitness in populations ranging in size from 7 to 12,000 flowers. In a field experiment, we applied four pollination treatments and also recorded fly density in 28 natural T. europaeus populations. The fitness of the offspring from 19 populations was studied in a common garden experiment. In both approaches, a reduction in the fitness of small host plant populations could be demonstrated. Fitness loss can be put down to the quantitative and qualitative limitation of pollen caused by inbreeding and the negative feedback on relative seed set caused by the reduced ability of small plant populations to support a sufficiently large fly population. Although increases in fly density are associated with rising predation costs, the plant species’ net benefit is a positive function of its population size. Our study highlights the reproductive variability of the TrolliusChiastocheta interaction along a population size gradient in a marginal region of its range, thus contributing to the understanding of the overall variability of this mutualism.  相似文献   

14.

Background

Newly formed platelets are associated with increased aggregation and adverse outcomes in patients with coronary artery disease (CAD). The mechanisms involved in the regulation of platelet turnover in patients with CAD are largely unknown.

Aim

To investigate associations between platelet turnover parameters, thrombopoietin and markers of low-grade inflammation in patients with stable CAD. Furthermore, to explore the relationship between platelet turnover parameters and type 2 diabetes, prior myocardial infarction, smoking, age, gender and renal insufficiency.

Methods

We studied 581 stable CAD patients. Platelet turnover parameters (immature platelet fraction, immature platelet count, mean platelet volume, platelet distribution width and platelet large cell-ratio) were determined using automated flow cytometry (Sysmex XE-2100). Furthermore, we measured thrombopoietin and evaluated low-grade inflammation by measurement of high-sensitive CRP and interleukin-6.

Results

We found strong associations between the immature platelet fraction, immature platelet count, mean platelet volume, platelet distribution width and platelet large cell ratio (r = 0.61–0.99, p<0.0001). Thrombopoietin levels were inversely related to all of the platelet turnover parameters (r = −0.17–−0.25, p<0.0001). Moreover, thrombopoietin levels were significantly increased in patients with diabetes (p = 0.03) and in smokers (p = 0.003). Low-grade inflammation evaluated by high-sensitive CRP correlated significantly, yet weakly, with immature platelet count (r = 0.10, p = 0.03) and thrombopoietin (r = 0.16, p<0.001). Also interleukin-6 correlated with thrombopoietin (r = 0.10, p = 0.02).

Conclusion

In stable CAD patients, thrombopoietin was inversely associated with platelet turnover parameters. Furthermore, thrombopoietin levels were increased in patients with diabetes and in smokers. However, low-grade inflammation did not seem to have a substantial impact on platelet turnover parameters.  相似文献   

15.
This study investigates stable isotope signatures of five species of Silurian and Devonian deep-water, ahermatypic rugose corals, providing new insights into isotopic fractionation effects exhibited by Palaeozoic rugosans, and possible role of diagenetic processes in modifying their original isotopic signals. To minimize the influence of intraskeletal cements on the observed signatures, the analysed specimens included unusual species either devoid of large intraskeletal open spaces (''button corals'': Microcyclus, Palaeocyclus), or typified by particularly thick corallite walls (Calceola). The corals were collected at four localities in the Holy Cross Mountains (Poland), Mader Basin (Morocco) and on Gotland (Sweden), representing distinct diagenetic histories and different styles of diagenetic alteration. To evaluate the resistance of the corallites to diagenesis, we applied various microscopic and trace element preservation tests. Distinct differences between isotopic compositions of the least-altered and most-altered skeleton portions emphasise a critical role of material selection for geochemical studies of Palaeozoic corals. The least-altered parts of the specimens show marine or near-marine stable isotope signals and lack positive correlation between δ13C and δ18O. In terms of isotopic fractionation mechanisms, Palaeozoic rugosans must have differed considerably from modern deep-water scleractinians, typified by significant depletion in both 18O and 13C, and pronounced δ13C-δ18O co-variance. The fractionation effects exhibited by rugosans seem similar rather to the minor isotopic effects typical of modern non-scleractinian corals (octocorals and hydrocorals). The results of the present study add to growing evidence for significant differences between Scleractinia and Rugosa, and agree with recent studies indicating that calcification mechanisms developed independently in these two groups of cnidarians. Consequently, particular caution is needed in using scleractinians as analogues in isotopic studies of extinct coral lineages. Answering some of the pertinent palaeoecological questions, such as that of the possibility of photosymbiosis in Palaeozoic corals, may not be possible based on stable isotope data.  相似文献   

16.
Objective of this paper was to investigate the incidence, potential geographical clusters and the completeness of the amyotrophic lateral sclerosis (ALS) registry in Southern Germany (Swabia).Age-standardized incidence rates (ASR) and ratios (SIR) as well as 95% confidence intervals (CI) were estimated at county level. Capture-recapture (CARE) procedures were applied taking data source dependency into account to estimate the quality of case ascertainment in the ALS registry Swabia. We identified 438 ALS cases (53% men, 47% women) in the target population of about 8.4 Mio inhabitants. The gender ratio (men∶women) was 1.1∶1. The mean age at onset of ALS was 63.8 (SD = 11.9) years for men and 66.0 (12.2) for women. The age distribution peaked in the age group 70–74 years. The ASR of ALS was 2.5 per 100,000 person years (PY; 95% CI: 2.3–2.7). The mean SIR was 1.1 per 100,000 PY (95% CI: 1.0–1.2). High SIR suggesting geographical clusters were observed in two counties (Göppingen and Bodenseekreis), but the variation was not statistically significant (p-values = 0.2 and 0.5). The percentage of CARE estimated missing cases was 18.9% in the registry yielding an ASR of 3.1 per 100,000 PY. The high coverage of the CARE estimated completeness of the ALS registry Swabia indicates excellent quality for future projects. Regional variations have to be investigated further.  相似文献   

17.
生物多样性常常和生态系统多功能性(生态系统同时提供多个生态系统功能的能力)正相关。然而,生物多样性与生态系统多功能性的关系是否依赖于生态系统功能的数目有诸多争议。其中,生物多样性对生态系统多功能性的影响或许不随生态系统功能数目的变化而变化,或者随生态系统功能数目的增多而增强。我们期望通过研究不同生态系统多功能性指数的统计原理来解决这些争议。 我们使用了模型模拟和一系列来自不同空间尺度(从局域到全球)和不同生物群系(温带和高寒草地、森林和干旱地)的经验数据。我们回顾了量化生态系统多功能性的三种方法,包括平均值法、加和法和阈值法。我们发现随着生态系统功能数目的增加,生物多样性与生态系统多功能性的关系要么不变,要么增强。这些结果可由平均和加和的多功能性指数的统计原理来解释。具体来讲,当利用生态系统功能的平均值计算多功能性指数时,由于多样性对多功能性的效应等于多样性对单个生态系统功能效应的平均值,所以不会随生态系统功能数目的变化而变化。同样的道理,当利用单个生态系统的加和值计算多功能性指数时,多样性的效应会随着生态系统功能数目的增加而增强。我们提出了一个改进的多功能性指数,将平均或加和多功能性指数转化为标准化的多功能性指数, 以便于对不同研究的结果进行比较。此外,我们提出了基于变量数值范围的标准化方法来解决阈值法的数学假象问题(多样性效应随生态系统功能数目的增加而增强)。我们的研究结果表明,量化多功能性指数的方法不同,结果也不同。因此,有必要加深对不同方法数理基础的理解。而标准化的多功能性指数为比较不同研究中的生物多样性与生态系统多功能性的关系提供了有效的方法。  相似文献   

18.
Limited spatial resources available for conservation lead to controversy about whether to apply single-species management or ecosystemary approaches in order to maintain biodiversity. In this study I analyse changes in a community of breeding coastal birds over a 90-year period, in order to examine whether natural processes on an unmanaged island are in accordance with requirements to save endangered species. Both diversity and species richness of the community increased significantly over time, and evenness increased after having been severely reduced by human impact. Diversity, evenness and species richness seemed to approach an equilibrium in the past decade, but number of breeding pairs declined as a consequence of altered natural disturbance regime. Species identity changed over time, with two initially very common species recently becoming locally extinct. These species are of high conservation concern, and their disappearance causes a problem for the concept of naturalness on islands. I conclude that natural processes need to be applied to the entire landscape in order to maintain dynamic processes that are essential for the survival of these species. The natural changes on the island should not be interrupted, but rather demonstrated to the public in order to increase conservation mindedness and gain support for changes in anthropogenic influences on a larger spatial scale.  相似文献   

19.
The timing of river entry in the Atlantic salmon is known to depend on genetic, demographic and environmental factors, but little is known about the relative magnitude of among population and among year variation and covariation in this respect in natural state Atlantic salmon rives. To investigate this, variability in the timing of river entry in three historical Finnish Atlantic salmon populations were analyzed using salmon trap data collected during 1870- 1902. The analyses reveled that 1 ) the timing of river entry differed substantially and consistently among the rivers, and that 2) variation among the rivers was much larger than variation among years. Annual variations were not explained by regional environmental conditions, whereas in one river the timing of the local flood peak was a significant predictor of the timing of river entry. Differences in the timing of salmon entry to geographically closely situated rivers suggests that a regionally fixed opening date for coastal fisheries might not be the best management strategy as it may lead to uneven exploitation of salmon populations from different rivers [ Current Zoology 55 (5) : 342 - 349, 2009] .  相似文献   

20.
Using the 2002 All-Russian population census data, the parameters of differential fertility as a component of natural selection (Crow??s indices) have been calculated for women of seven age cohorts of the seven most numerous ethnic groups of the Republic of Dagestan. It has been shown that in the population of Dagestan in the second half of the 20th century the intensities of two types of selection tended to decrease, viz., intragroup selection relaxed in each ethnic group due to considerable reduction of interfamily variance in fertility and intergroup selection relaxed due to reduction of interethnic differences in fertility. A reduction of the average number of offspring (k) was observed in all ethnic groups, suggesting the spread of birth regulation practices (abortion and contraception). Nevertheless, all Muslim groups (aboriginal Dagestan ethnic groups and Azerbaijanis) are still characterized by an extended pattern of reproduction (2.7 < k < 3.3); in Russians k = 2.1. Interethnic differentials in natural reproduction rates, along with migration processes, account for the dynamics of the ethnic composition and gene-pool structure of the population of the Republic of Dagestan.  相似文献   

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