228 research outputs found

    Neue Entwicklungstendenzen im politischen System Russlands

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    JĂŒngste soziologische Untersuchungen belegen, dass sich, auf Grund des wirtschaftlichen Aufschwungs und der StabilitĂ€t im vergangenen Jahrzehnt, in Russland und vor allem in Moskau eine beachtliche Mittelschicht herausbilden konnte, die eine Herausforderung fĂŒr das bestehende politische System darstellt. Dies zeigt sich an einer zunehmenden Nachfrage nach Parteien und ReprĂ€sentanten außerhalb des offiziellen politischen Spektrums sowie einer wachsenden Protestbereitschaft. FĂŒr das politische System und vor allem das Parteiensystem erwachsen hieraus bedeutende Herausforderungen, die zu einer Zunahme der politischen Konkurrenz fĂŒhren werden

    The Effects of Larval Nutrition on Reproductive Performance in a Food-Limited Adult Environment

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    It is often assumed that larval food stress reduces lifetime fitness regardless of the conditions subsequently faced by adults. However, according to the environment-matching hypothesis, a plastic developmental response to poor nutrition results in an adult phenotype that is better adapted to restricted food conditions than one having developed in high food conditions. Such a strategy might evolve when current conditions are a reliable predictor of future conditions. To test this hypothesis, we assessed the effects of larval food conditions (low, improving and high food) on reproductive fitness in both low and high food adults environments. Contrary to this hypothesis, we found no evidence that food restriction in larval ladybird beetles produced adults that were better suited to continuing food stress. In fact, reproductive rate was invariably lower in females that were reared at low food, regardless of whether adults were well fed or food stressed. Juveniles that encountered improving conditions during the larval stage compensated for delayed growth by accelerating subsequent growth, and thus showed no evidence of a reduced reproductive rate. However, these same individuals lost more mass during the period of starvation in adults, which indicates that accelerated growth results in an increased risk of starvation during subsequent periods of food stress

    Frequency of chromosomal aberrations in material from abortions

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    Summary Examination of fetal tissue from spontaneous miscarriages shows that 50-70% of them were caused by abnormalkaryotype. The most frequent genetic abnormalities include abnormal number of chromosomes, aberration of chromosomes structure and chromosome mosaic anomalies. Objective: the aim of the study was to find out whether there is any difference in the frequency of chromosomal aberrations in patients who miscarried for the first time comparing to patients with recurrent miscarriages. Material and methods: Examination was performed on 129 miscarriage material samples from 128 women. Fluorescent hybridization in-situ (FISH) was used for genetic examination. Results: We received 120 results in which 45 (37,5%) were abnormal. The most frequent chromosomal aberration was trisomy, followed by triploidy and monosomy of chromosome X. Among 59 samples from first miscarriage we found 25 abnormal karyotypes. In the 61 samples from the second, third and the next miscarriages we found 20 chromosomal abnormalities. Conclusions: Frequency of chromosomal aberrations in the tissue from the first miscarriage is significantly higher than in samples from second or following miscarriages, which means that genetic factors are less likely to induce recurrent miscarriages. Genetic results confirm that most chromosomal abnormalities arise de-novo

    Do chromosomal abnormalities reappear in subsequent pregnancies and how often?

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    Abstract Objective: Genetic factors are the most common causes of spontaneous abortions. 50% to 80% of first-trimester abortions reveal chromosome abnormalities. Evidence for the recurrence of the same or another chromosome abnormality in the next pregnancy is scarce. The aim: The aim of our study was to estimate recurrence risk of abortus aneuploidy and to find out whether karyotyping of the abortus allows the prognose subsequent pregnancy outcomes. Material and methods: Paraffin-embedded chorions have undergone cytogenetic examination using FISH with chromosome-specific probes. 57 chorions from 26 women have been assessed, including chorions from two consecutive abortions from 18 women and chorions from three consecutive abortions from 5 women. Results: 38.6% of 57 specimens had chromosome aberrations. The most prevalent anomalies were 16, 21 and 18 trisomies. 23 patients had a subsequent abortion karyotyped; 15 had a normal initial karyotype and 8 had an aberrant initial karyotype. 3 out of the 8 patients had a repeated chromosome anomaly. 5 out of the 15 patients who initially miscarried an aneuploid embryo, had a subsequent miscarriage of an aneuploid embryo. Only 3 (13.04%) out of the 23 patients displayed aneuploidy in each abortus. Conclusion: 1. Chromosome aberrations can reappear in subsequent pregnancies in the same patient and may be the cause of recurrent miscarriages. 2. The value of embryo/fetal karyotyping is not decisive in prognosis of subsequent pregnancy outcome. 3. Abnormal fetal karyotype can occur regardless of other causes of pregnancy loss

    Growth rates of black soldier fly larvae fed on fresh human faeces and their implication for improving sanitation.

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    OBJECTIVES: To determine the capacity of black soldier fly larvae (BSFL) (Hermetia illucens) to convert fresh human faeces into larval biomass under different feeding regimes, and to determine how effective BSFL are as a means of human faecal waste management. METHODS: Black soldier fly larvae were fed fresh human faeces. The frequency of feeding, number of larvae and feeding ratio were altered to determine their effects on larval growth, prepupal weight, waste reduction, bioconversion and feed conversion rate (FCR). RESULTS: The larvae that were fed a single lump amount of faeces developed into significantly larger larvae and prepupae than those fed incrementally every 2 days; however, the development into pre-pupae took longer. The highest waste reduction was found in the group containing the most larvae, with no difference between feeding regimes. At an estimated 90% pupation rate, the highest bioconversion (16-22%) and lowest, most efficient FCR (2.0-3.3) occurred in groups that contained 10 and 100 larvae, when fed both the lump amount and incremental regime. CONCLUSION: The prepupal weight, bioconversion and FCR results surpass those from previous studies into BSFL management of swine, chicken manure and municipal organic waste. This suggests that the use of BSFL could provide a solution to the health problems associated with poor sanitation and inadequate human waste management in developing countries

    Body condition as a quantitative tool to guide hand-rearing decisions in an endangered seabird

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    This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.The use of wildlife rehabilitation for conservation is growing, but quantitative criteria are rarely used to guide whether and when to remove animals from the wild. Since 2006, large numbers of African penguin Spheniscus demersus chicks have been abandoned annually when adults enter moult with dependent young still in the nest. As part of conservation initiatives for this endangered species, these chicks were collected and hand reared to fledging age. Post-release survival has been well documented; in this study we develop models to predict survival of individuals during rehabilitation with the aim of improving hand-r earing success and guiding the use of scarce resources. For 1455 chicks abandoned between 2008 and 2013, we assessed whether a chick body condition index (BCI) could predict outcome (death or release) and time spent in rearing. In addition, for a subset of 173 chicks in 2012, we assessed whether BCI at admission influenced chick growth rates during rehabilitation and examined whether the use of additional structural measurements and sex provided additional power to predict outcome. Models predicted an 82.9% (95% confidence interval: 73.3–89.5%) release rate for chicks admitted with a BCI > 0, the proposed guideline for removal from colonies. This fell below 50% for BCIs  <  −1.05; 66% of chicks were admitted with BCIs between these thresholds. Adding bill length to BCI improved the relative model fit, but in both cases only ~70% of rehabilitation outcomes were correctly predicted. Chicks that grew more quickly were more likely to be released and, for those that were released, had lower BCI at admission suggesting compensatory growth. Chicks were generally removed at an appropriate time to ensure successful hand-rearing. However, 32% were admitted in good condition, highlighting the importance of using adaptive management to guide wildlife rehabilitation and the allocation of conservation resources.This study contributes to the African Penguin Chick Bolstering Project (CBP) and benefitted from donations to the CBP from 46 supporter organizations (listed at http://tinyurl.com/SANCCOB-CBP). In addition, the Earthwatch Institute (N.J.P., R.B.S.), the Leiden Conservation Foundation (R.B.S.) and our institutions provided financial support. We thank the staff members and volunteers of SANCCOB, CapeNature, the City of Cape Town's Environmental Resource Management Department, the IFAW oil spill response team who helped to rear the chicks

    Adaptation to divergent larval diets in the medfly, Ceratitis capitata

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    Variation in diet can influence the timing of major life history events and can drive population diversification and ultimately speciation. Proximate responses of life histories to diet have been well studied. However, there are scant experimental data on how organisms adapt to divergent diets over the longer term. We focused on this omission by testing the responses of a global pest, the Mediterranean fruitfly, to divergent selection on larval diets of different nutritional profiles. Tests conducted before and after 30 generations of nutritional selection revealed a complex interplay between the effects of novel larval dietary conditions on both plastic and evolved responses. There were proximate-only responses to the larval diet in adult male courtship and the frequency of copulation. Males on higher calorie larval diets consistently engaged in more bouts of energetic courtship. In contrast, following selection, larval development time and egg to adult survival showed evidence of evolved divergence between diet regimes. Adult body size showed evidence for adaptation, with flies being significantly heavier when reared on their ‘own’ diet. The results show the multifaceted responses of individuals to dietary selection and are important in understanding the extreme generalism exhibited by the medfly

    Exploring evolution of maximum growth rates in plankton

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    Evolution has direct and indirect consequences on species–species interactions and the environment. However, Earth systems models describing planktonic activity invariably fail to explicitly consider organism evolution. Here we simulate the evolution of the single most important physiological characteristic of any organism as described in models—its maximum growth rate (ÎŒm). Using a low-computational-cost approach, we incorporate the evolution of ÎŒm for each of the plankton components in a simple Nutrient-Phytoplankton-Zooplankton -style model such that the fitness advantages and disadvantages in possessing a high ÎŒm evolve to become balanced. The model allows an exploration of parameter ranges leading to stresses, which drive the evolution of ÎŒm. In applications of the method we show that simulations of climate change give very different projections when the evolution of ÎŒm is considered. Thus, production may decline as evolution reshapes growth and trophic dynamics. Additionally, predictions of extinction of species may be overstated in simulations lacking evolution as the ability to evolve under changing environmental conditions supports evolutionary rescue. The model explains why organisms evolved for mature ecosystems (e.g. temperate summer, reliant on local nutrient recycling or mixotrophy), express lower maximum growth rates than do organisms evolved for immature ecosystems (e.g. temperate spring, high resource availability)

    Age, condition and dominance-related sexual ornament size before and during the breeding season in the black grouse Lyrurus tetrix

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    Male ornaments function as honest cues of male quality in many species and are subject to intra- and intersexual selection. These ornaments are generally studied during peak expression, however their size outside the breeding season may determine ultimate ornament size and costliness, and as such reproductive success. We investigated whether male black grouse Lyrurus tetrix eye comb size was related to age, condition and measures of male dominance before and during the breeding season. Total combined eye comb size began to increase ~70 d before the start of the breeding season. Adult males (aged ≄ 2 yr old) had consistently larger eye combs than younger males (1 yr old) both before and during the breeding season. Heavier and more dominant adult males (attending the lek more frequently and successfully reproducing) had larger eye combs. For younger males, those that were heavier had larger eye combs. Additionally, males that spent more time on the lek showed increased eye comb size as the breeding season approached. Overall we find that ornament size is positively related to dominance and condition before and during the breeding season. Since dominance is accrued through year-round interactions in many species, the ability to maintain larger signals over prolonged periods, including outside of the breeding season, is likely to be beneficial for adults. For younger males, it is likely that they cannot sustain or are constrained from producing larger eye combs over long periods of time. They therefore prioritise growth of their ornaments later, and according to the amount of time they spend on the lek

    Quantitative genetic analysis of responses to larval food limitation in a polyphenic butterfly indicates environment and trait-specific effects

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    Different components of heritability, including genetic variance (VG), are influenced by environmental conditions. Here, we assessed phenotypic responses of life-history traits to two different developmental conditions, temperature and food limitation. The former represents an environment that defines seasonal polyphenism in our study organism, the tropical butterfly Bicyclus anynana, whereas the latter represents a more unpredictable environment. We quantified heritabilities using restricted maximum likelihood (REML) procedures within an “Information Theoretical” framework in a full-sib design. Whereas development time, pupal mass, and resting metabolic rate showed no genotype by- environment interaction for genetic variation, for thorax ratio and fat percentage the heritability increased under the cool temperature, dry season environment. Additionally, for fat percentage heritability estimates increased under food limitation. Hence, the traits most intimately related to polyphenism in B. anynana show the most environmental-specific heritabilities as well as some indication of cross-environmental genetic correlations. This may reflect a footprint of natural selection and our future research is aimed to uncover the genes and processes involved in this through studying season and condition dependent gene expression.Peer reviewe
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