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401.
Bart Wouters Marijn Nijssen Gertjan Geerling Hein Van Kleef Eva Remke Wilco Verberk 《Journal of Coastal Conservation》2012,16(1):89-99
Encroachment of tall grasses and shrubs in coastal dunes has resulted in loss of vegetation heterogeneity. This is expected
to have negative effects on animal diversity. To counteract encroachment and develop structural heterogeneity grazing is a
widely used management practice. Here, we aim to functionally interpret changes in vegetation composition and configuration
following grazing management on habitat suitability for sand lizards. Aerial photographs taken over a period of 16 years were
used to quantify changes in vegetation composition. A GIS-based method was developed to calculate habitat suitability for
sand lizards in a spatially explicit manner, encompassing differences in vegetation structure and patch size. From 1987 to
2003 dune vegetation shifted from small patches of moss and sand to larger patches covered by shrubs and grasses. Grazing
management did not have any significant effect on the overall level of heterogeneity, measured as habitat suitability for
sand lizards. However, on a more local scale highly suitable patches in 1987 were deteriorating whereas unsuitable patches
became more suitable in 2003. This inversion results from a broad shift with shrubs being a limiting habitat element in 1987
to sandy patches being the limiting element in 2003. Future changes are believed to negatively impact sand lizards. The habitat
suitability model has proven to be a useful tool to functionally interpret changes in coastal dune vegetation heterogeneity
from an animal’s perspective. Further research should aim to include multiple species operating on different scale levels
to fully capture the natural landscape dynamics. 相似文献
402.
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404.
Understanding the demography and function of biotope-forming seaweed species is of great importance for the conservation of
the target species itself, as well as its associated organisms. The brown seaweed Ascophyllum nodosum is fundamental for the functioning of coastal marine ecosystems in the North Atlantic. In this study, we use a data-based
size-classified matrix model to investigate the temporal and spatial variability in demography, and the environment-specific
stochastic sensitivity and elasticity, of two A. nodosum populations, one in western Sweden and one on the Isle of Man in the Irish Sea. A significant difference between the two
populations was that the Swedish population had comparably low and more variable stochastic population growth rate (λ
s). This pattern was partly explained by the relatively high and varying mortality rates during extreme ice-years in Sweden,
and by the lower survival of small individuals during all years. There were also fewer large individuals in Sweden due to
lower transitions to the larger size-classes and higher probability of shrinkage. Sensitivities were analogous in the two
populations, and showed a high selection pressure for increased individual growth. Elasticities were also similar, with the
exception that survival of the smallest individuals (i.e., transition a
1,1), had a higher elasticity on the Isle of Man. Overall, the stochastic growth rate (λ
s) was most sensitive to proportional changes in loop- (i.e., survival within size-class) and, to some extent, growth-transitions
in both study areas. These results show that structurally and demographically diverging A. nodosum populations may be similarly sensitive to changes in vital rates. This, in turn, indicates a plastic life history of A. nodosum that may cope with large environmental variability. The results further suggest that environmental change affecting the survival
or growth of the larger, reproductive A. nodosum individuals could have severe and regional effects on the abundance and biomass of this species, with potential negative
effects on the biodiversity of the associated communities. 相似文献
405.
406.
The diagnosis of chromosomal mosaicism in the preimplantation and prenatal stage is fraught with uncertainty and multiple factors need to be considered in order to gauge the likely impact. The clinical effects of chromosomal mosaicism are directly linked to the type of the imbalance (size, gene content, and copy number), the timing of the initial event leading to mosaicism during embryogenesis/fetal development, the distribution of the abnormal cells throughout the various tissues within the body as well as the ratio of normal/abnormal cells within each of those tissues. Additional factors such as assay noise and culture artifacts also have an impact on the significance and management of mosaic cases. Genetic counseling is an important part of educating patients about the likelihood of having a liveborn with a chromosome abnormality and these risks differ according to the time of ascertainment and the tissue where the mosaic cells were initially discovered. Each situation needs to be assessed on a case-by-case basis and counseled accordingly. This review will discuss the clinical impact of finding mosaicism through: embryo biopsy, chorionic villus sampling, amniocentesis, and noninvasive prenatal testing using cell-free DNA. 相似文献
407.
Kathrin B. Labrosse Johanna Buechel Huelya Guelmez Annkathrin Butenschoen Heidrun Schoenberger Eva Visca Andreas Schoetzau Gwendolin Manegold-Brauer 《黑龙江环境通报》2023,43(7):910-918
Objectives
The aim of this study was to examine the value of the sonographic measurements of the choroid plexus and the lateral ventricles at 11–14 gestational weeks in fetuses that had the diagnosis of second-trimester ventriculomegaly (VM) as a clinical reference.Methods
The standard axial plane used for biparietal diameter measurement from 2D stored images in the first trimester was used to calculate the ratio between the choroid plexus and lateral ventricle diameter (PDVDR), the choroid plexus and lateral ventricle length (PLVLR) and the choroid plexus and lateral ventricle area (PAVAR) in 100 normal and 15 fetuses diagnosed with second-trimester VM.Results
In fetuses with VM, the measurements of PDVDR, PLVLR and PAVAR were all significantly smaller compared to normal fetuses (p = < 0.001, <0.001, <0.01). Four out of seven cases with mild VM had measurements below the 5th percentile (57%). 75% of cases with moderate or severe VM had at least one measurement below the 5th percentile.Conclusions
Since the axial plane of the fetal head is obtained in all first-trimester routine screenings, the measurements of PDVDR, PLVLR and PAVAR could easily be integrated into routine examinations for an early detection of VM. 相似文献408.
Montse Pauta Raigam J. Martinez-Portilla Eva Meler Juan Otaño Antoni Borrell 《黑龙江环境通报》2023,43(5):596-604
The aim of this study was to determine the diagnostic yield of exome sequencing (ES) above that of chromosomal microarray analysis (CMA) or karyotyping in fetuses with isolated fetal growth restriction (FGR). This was a systematic review conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Selected studies included those with (a) only fetuses with FGR in the absence of fetal structural anomalies and (b) negative CMA or karyotyping results. Only positive variants classified as likely pathogenic or pathogenic determined as causative of the fetal phenotype were considered. A negative CMA or karyotype result was treated as the reference standard. Eight studies with data on ES diagnostic yield, including 146 fetuses with isolated FGR, were identified. Overall, a pathogenic variant determined as potentially causative of the fetal phenotype was found in 17 cases, resulting in a 12% (95% CI: 7%–18%) incremental performance pool of ES. The vast majority were studied before 32 weeks'gestation. In conclusion, a monogenic disorder was prenatally found in association with apparently isolated FGR in 12% of these fetuses. 相似文献
409.
410.
Jesús Miguel Avilés Eva María Bootello Mercedes Molina-Morales Juan Gabriel Martínez 《Behavioral ecology and sociobiology》2014,68(8):1287-1298
Studies of antiparasite defences against cuckoo parasites have largely neglected the possibility that behavioural components of host defence may correlate giving rise to a behavioural syndrome. Furthermore, the different contribution of the host’s sex in nest defence has traditionally been disregarded. Here, we studied magpie (Pica pica) mobbing behaviour towards dummies of great spotted cuckoo (Clamator glandarius) and non-harmful hoopoes (Upupa epops) and egg rejection of parasite eggs in a population of colour-banded magpies. We predicted a positive correlation between the intensity of nest defence and egg rejection within each sex and that females respond more intensely than males to the threat of brood parasitism as they undertake incubation. Magpie males, but not females, defended their nests more intensely in those nests in which cuckoo model eggs were rejected. Individual magpies did significantly differ in their baseline level of nest attentiveness; however, there were no individual differences once pair identity was considered. Males and females defended their nests more intensely when it was exposed to the presence of a great spotted cuckoo dummy. Males, but not females, were more prone to appear at their nests, and females, but not males, were more prone to defend more intensely when their nests were challenged by a parasite threat. Our results thus agree with the view that mobbing behaviour and egg rejection in magpies may actually constitute a pseudosyndrome and highlight the necessity to integrate interindividual variation and the sex of the host in studies of the evolution of host defences. 相似文献