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Mate choice is favored by indirect selection if choosy females mate with males of high genetic quality. We believe, however, that testing hypotheses about indirect selection has been constrained by how we conceptualize and therefore empirically measure male genetic quality. Here, we argue that genetic quality is the breeding value of an individual for total fitness. We can therefore learn little about genetic quality from measures of only a few fitness components. We explain breeding value for total fitness, drawing on concepts from life-history theory and quantitative genetics, and suggest how approaches incorporating these insights might result in empirical progress. 相似文献
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Much attention has been directed toward the measurement of health outcomes and the quality of medical care. Some policymakers tout outcomes measurement as a promising tool for improving health care, while others question whether current quality of care assessment is valid and of practical importance. Although significant advances have been made in the ability to measure quality of care with validity, several major methodological challenges remain. We analyze the quality of quality of medical care measures, using a conceptual framework that outlines the purpose of the measures; paradigms of the quality of care, including Donabedian's structure-process-outcome model and continuous quality improvement; and other key elements, such as scope, time, unit of analysis, and perspectives. Patient preferences and organizational contexts have been underemphasized, and should be incorporated into the framework for conceptualizing quality of care. Quality of care has relativistic and dynamic aspects. Different perspectives lead to different views of what high quality care is, and quality of care is a changing concept since medical science and treatment are constantly evolving. The most appropriate quality measures depend upon whose perspective one takes and the purpose of the measures; if the measures are chosen wisely, the current state of quality of medical care measurement is adequate for both accountability and quality improvement. 相似文献
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Could hosts considered as low quality for egg-laying be considered as high quality for host-feeding?
When parasitoid females encounter a host, they can either lay an egg and thus invest in current reproduction or feed on the host and thus invest in future reproduction. However, hosts could have different values according to their parasitized status. Whereas already parasitized hosts represent poor quality for egg-laying, they could have a high nutritive value for feeding. Moreover, the optimal strategy adopted generally depends on the females’ physiological state. In this study, the impact of the females’ physiological state on their reproductive strategies was investigated in the solitary parasitoid Anisopteromalus calandrae. We analysed how their age and diet influenced (i) the use of hosts (feeding vs. oviposition) and (ii) host selection (previously parasitized vs. unparasitized). Our results show that both age and diet influence the reproductive strategy of A. calandrae females: old females fed with the poorer diet laid fewer eggs and made more host-feeding than others. Females also showed a preference for already parasitized hosts for feeding. This strategy cannot be explained by the nutritive value of haemolymph, as parasitized hosts carry fewer lipids. However, as parasitized hosts are also paralyzed, it could be less costly to feed on them than on unparasitized hosts. 相似文献
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Hans Holtan Hans Olav Ibrekk 《Journal of Aquatic Ecosystem Stress and Recovery (Formerly Journal of Aquatic Ecosystem Health)》1993,2(2):73-79
General water quality criteria for Norwegian Waters were developed by the State Pollution Control Authority in the earch 1980s. The need for further refinement of these criteria became apparent in the mid-1980s. New water quality criteria were developed in conjunction with the development of a system for assessment of water uses. Two fundamental principles are outlined for determining the classification of water quality in Norway:
- The classification for polluted water. The basis for this system is the natural water quality without any form of influence from man. It is the influence of pollution on the water quality, or the difference between the natural water quality and the water quality today that is classified.
- The system for assessment of water quality for various uses is based both on the existing water quality and some physical and practical properties of the environment. The water quality criteria are specific for various uses.
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Wetland plant decomposition under different nutrient conditions: what is more important, litter quality or site quality? 总被引:3,自引:0,他引:3
Plants in nutrient poor environments are often characterized by high nutrient resorption resulting in poor litter quality
and, consequently, slow decomposition. We used oligotrophic, P-limited herbaceous wetlands of northern Belize as a model system,
on which to document and explain how changes in nutrient content along a salinity gradient affect decomposition rates of macrophytes.
In 2001 we established a nutrient addition experiment (P, N, and N&P) in 15 marshes of a wide range of water conductivities
(200–6000 μS), dominated by Eleocharis spp. To determine what is more important for decomposition, the initial litter quality, or site differences, we used reciprocal
litter placement and cellulose decomposition assay in a combined “site quality” and “litter quality” experiment. Our prediction
of the positive effects of P-enrichment on decomposition rate due to both the quality of litter and the site was confirmed.
The site effect was stronger than the litter quality although both were highly significant. Strong site quality effect was
apparently the result of more active decomposer community in P-enriched plots as supported by finding of higher microbial
biomass in litter decomposing there. The strong effect of site quality on decomposition was further confirmed by the cellulose
assay. The cellulose decomposition was significantly slower at high salinity sites indicating lower decomposer microbial activity.
Litter nutrient N and P content and nutrient ratios were well correlated with decomposition with the best fit found for log
C/P. At C/P mass ratio of >4000 decomposition processes were extremely slow. We hypothesize that in a long run, the increased
decomposition will compensate the increase in primary production resulting from increased nutrient loading and there will
be no differences in accumulation of organic material between the controls and nutrient enriched plots. 相似文献
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Ian M. Campbell 《Oecologia》1989,81(3):341-344
Summary The hypothesis that annual climatic variation can affect the nutritive value of host-plant tissue for a herbivore was tested. Larvae of a single generation of western spruce budworm, Choristoneura occidentalis Free., were fed foliages that had been collected on five consecutive springs from a stand of balsam fir Abies balsamea (L.) Mill. Budworm of both sexes were about 20 percent heavier at pupation when fed folages that had been produced in early rather than later spring seasons. This could result in an estimated 25 percent difference in the reproductive rate of females. It is concluded that annual variations in spring climate can affect the nutritive value of forage. 相似文献
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Reich TE Lindstedt SL LaStayo PC Pierotti DJ 《American journal of physiology. Regulatory, integrative and comparative physiology》2000,278(6):R1661-R1666
During locomotion, major muscle groups are often activated cyclically. This alternate stretch-shorten pattern of activity could enable muscle to function as a spring, storing and recovering elastic recoil potential energy. Because the ability to store and recover elastic recoil energy could profoundly affect the energetics of locomotion, one might expect this to be an adaptable feature of skeletal muscle. This study tests the hypothesis that chronic eccentric (Ecc) training results in a change in the spring properties of skeletal muscle. Nine female Sprague-Dawley rats underwent chronic Ecc training for 8 wk on a motorized treadmill. The spring properties of muscle were characterized by both active and passive lengthening force productions. A single "spring constant (Deltaforce/Deltalength) from the passive length-tension curves was calculated for each muscle. Results from measurements on long heads of triceps brachii muscle indicate that the trained group produced significantly more passive lengthening force (P = 0.0001) as well as more active lengthening force (P = 0.0001) at all lengths of muscle stretch. In addition, the spring constants were significantly different between the Ecc (1.71 N/mm) and the control (1.31 N/mm) groups. A stiffer spring is capable of storing more energy per unit length stretched, which is of functional importance during locomotion. 相似文献
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Carmen L. Elias Natividade Vieira Maria J. Feio Salomé F. P. Almeida 《Hydrobiologia》2012,695(1):223-232
To understand whether seasons influence the ecological quality assessment of streams on the basis of diatoms, a study was
undertaken in two lowland water courses located in northwest Portugal, between autumn 2008 and summer 2009. Temporal variation
in the chemical pollution of these streams was small as revealed by a number of physical and chemical parameters analyzed.
PERMANOVA global test revealed significant variation in water temperature among seasons. The diatom communities also showed
a temporal variation although not all the seasons were statistically different. The multidimensional scaling analysis showed
that the main differences in the diatom communities were between two groups of seasons: autumn/winter and spring/summer. Species
such as Cocconeis pseudolineata, Gomphonema parvulum var. exilissimum, Fragilaria vaucheriae, Encyonema minutum, and Nitzschia recta were more abundant in spring/summer, while species such as Mayamaea atomus and Nitzschia pusilla were more abundant in autumn/winter. The BIOENV routine confirmed that the biological and temperature patterns are highly
correlated. Despite the effects observed on diatom communities, these differences were buffered by the EQR (IPS) values which
do not reflect seasonal differences. Therefore, the use of the index IPS seems to allow the monitoring of the streams’ ecological
quality throughout the year without the interference of the natural temporal variability of diatom communities. 相似文献
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External quality control programmes carried out by central laboratories have been long established in human andrology with the aim of enhancing the accuracy and reproducibility of semen assessment. Compared to human, demands on boar semen assessment in AI stations are more complex, with the need both to identify boars with poor ejaculate quality and to monitor individual boar differences for semen storage. Additionally, appropriate assessment serves as a control instrument to ensure the security and efficiency of semen processing. Despite current limitations regarding the ability of sperm assays to estimate the potential fertility of males, it is evident that boar fertility is related to certain conventional semen tests, e.g. sperm morphology. In central studies carried out on stored semen from 11 AI stations, flow cytometric assessment of plasma and acrosome membrane integrity proved to be more sensitive in detecting sperm damage associated with ageing and temperature stress as compared to light microscopy. Membrane integrity of stored semen differed between AI stations indicating significant influences of semen processing on sperm quality. Thus external control of semen quality in reference laboratories may be useful to monitor the efficiency of internal semen quality control in individual AI stations, to identify males with lower semen quality and/or poor response to semen storage, and to verify the precision of sperm counting. The possibility that central laboratories with sufficient resources may be able to identify functionally different responding sperm subpopulations for better estimation of fertility is discussed. Ideally, external quality control schemes for AI stations would comprise application of validated tests with high relevance for fertility (including bacterial status), analysis of semen processing on the AI station, and training courses for laboratory personnel. 相似文献
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Fluctuating asymmetry (FA) in ornamental characters may reflect developmental stability in the translation from genotype
to phenotype. Antlers of reindeer show FA, are visually conspicuous ornaments and are important in intraspecific assessment.
We show that there is a negative relationship between size and asymmetry in visual antler characteristics (i.e., antler length
and number of tines) among free-ranging male reindeer in rut. This indicates that individuals that develop large ornaments
are better able to buffer developmental stress than individuals that develop small ornaments. There is no relationship between
asymmetry in antler length and asymmetry in jaw length, suggesting that symmetry in antlers does not reflect overall body
symmetry. This difference may be caused by trait-specific sensitivity to developmental stress. Such stress may partly be caused
by parasites, which show a positive association with asymmetry in antlers, but no relationship to asymmetry in jaws. Our results
indicate that antlers may be exposed to directional selection in a visual signaler-receiver system and that information about
parasite burden may be obtained from evaluation of asymmetry in antlers developed under exposure to a multitude of environmental
stresses.
Received: 8 October 1996 / Accepted: 13 January 1997 相似文献
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Guoliang Li Jingyi Yang Chunyuan Yang Minglu Zhu Yan Jin Michael A. McNutt 《Autophagy》2018,14(10):1742-1760
PTEN plays an important role in tumor suppression, and PTEN family members are involved in multiple biological processes in various subcellular locations. Here we report that PTENα, the first identified PTEN isoform, regulates mitophagy through promotion of PARK2 recruitment to damaged mitochondria. We show that PTENα-deficient mice exhibit accumulation of cardiac mitochondria with structural and functional abnormalities, and PTENα-deficient mouse hearts are more susceptible to injury induced by isoprenaline and ischemia-reperfusion. Mitochondrial clearance by mitophagy is also impaired in PTENα-deficient cardiomyocytes. In addition, we found PTENα physically interacts with the E3 ubiquitin ligase PRKN, which is an important mediator of mitophagy. PTENα binds PRKN through the membrane binding helix in its N-terminus, and promotes PRKN mitochondrial translocation through enhancing PRKN self-association in a phosphatase-independent manner. Loss of PTENα compromises mitochondrial translocation of PRKN and resultant mitophagy following mitochondrial depolarization. We propose that PTENα functions as a mitochondrial quality controller that maintains mitochondrial function and cardiac homeostasis.
Abbreviations: BECN1 beclin 1; CCCP carbonyl cyanide m-chlorophenylhydrazone; FBXO7 F-box protein 7; FS fraction shortening; HSPA1L heat shock protein family A (Hsp70) member 1 like; HW: BW heart weight:body weight ratio; I-R ischemia-reperfusion; ISO isoprenaline; MAP1LC3/LC3 microtubule associated protein 1 light chain 3; MBH membrane binding helix; MFN1 mitofusin 1; MFN2 mitofusin 2; Nam nicotinamide; TMRM tetramethylrhodamine ethyl ester; WGA wheat germ agglutinin 相似文献