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21.
In the frame of an epidemiological study carried out in the influence areas around the Spanish nuclear facilities (ISCIII-CSN, 2009. Epidemiological Study of The Possible Effect of Ionizing Radiations Deriving from The Operation of Spanish Nuclear Fuel Cycle Facilities on The Health of The Population Living in Their Vicinity. Final report December 2009. Ministerio de Ciencia e Innovación, Instituto de Salud Carlos III, Consejo de Seguridad Nuclear. Madrid. Available from: http://www.csn.es/images/stories/actualidad_datos/especiales/epidemiologico/epidemiological_study.pdf), annual effective doses to public have been assessed by the Spanish Nuclear Safety Council (CSN) for over 45 years using a retrospective realistic-dose methodology. These values are compared with data from natural radiation exposure. For the affected population, natural radiation effective doses are in average 2300 times higher than effective doses due to the operation of nuclear installations (nuclear power stations and fuel cycle facilities). When considering the impact on the whole Spanish population, effective doses attributable to nuclear facilities represent in average 3.5 × 10−5 mSv/y, in contrast to 1.6 mSv/y from natural radiation or 1.3 mSv/y from medical exposures.  相似文献   
22.
The current state of Mediterranean mountain areas has been driven by two main factors: intense traditional human activity and the dynamics of the ecosystem itself. In this study, we examine land-cover changes in a National Park in the Pyrenees mountains (NE Iberian Peninsula), which was designated a protected area 55 years ago. First, we have analyzed spatio-temporal changes in land-cover pattern and forest dynamics from 1957 to 2005. During this period, land-cover dynamics consisted of two main processes: (i) expansion of the forest area and (ii) increasing cover of forests already present in 1957. To analyze the role of the conservation level of the park, we have also compared the results obtained within the park with those of unprotected, peripheral areas. In the two areas with different protection level, dense forests increased throughout the period because of the reduction in forestry activities. The peripheral area showed a higher rate of forest-cover change from 1957 to 2005 compared to the National Park. This higher increase in forest cover in the peripheral area could be related to a higher proportion in the National Park of screes and rocky areas and to the decline and transformation of forest activities in these peripheral, lower elevation areas.  相似文献   
23.
A dicentric X chromosome was found in a female fetus during cytogenetic studies performed on amniotic cells. Blood samples from the parents showed normal karyotypes and the pregnancy was terminated. The mechanism for the formation of this ‘de novo’ rearrangement is discussed.  相似文献   
24.
Both sexes of Phoenicoprocta capistrata have functional tymbals. The scanning electron microscopy revealed differences in the morphology of these organs in males and females. Male tymbals have a well-developed striated band, constituted by 21 ± 2 regularly arranged striae whereas female tymbals lack a striated band. This type of sexual dimorphism is rare in Arctiidae. The recording of the sound produced by moths held by the wings revealed that while males produced trains of pulses organized in modulation cycles, females produced clicks at low repetition rate following very irregular patterns. Statistically, there are differences between sexes in terms of the duration of pulses, which were 355 ± 24 μs in the case of males and 289 ± 29 μs for females. The spectral characteristics of the pulses also show sexual dimorphism. Male pulses are more tuned (Q 10 = 5.2 ± 0.5) than female pulses (Q 10 = 2.7 ± 0.5) and have a higher best frequency (42 ± 1 kHz vs. 29 ± 2 kHz). To our knowledge, this is the first report on an arctiid moth showing sexual dimorphism in tymbal’s anatomy that leads to a best frequency dimorphism. Males produce sound at mating attempts. The sounds recorded during mating are modulation cycles with the same spectral characteristics as those recorded when males are held by the wings. The morphological and acoustic features of female tymbals could indicate a process of degeneration and adaptation to conditions under which the emission of complex patterns is not necessary. Frank Coro no longer works at Universidad de La Habana.  相似文献   
25.
Recent studies on ecological networks have quantified the contribution of ecological, historical, and evolutionary factors on the structure of local communities of interacting species. However, the influence of species’ biogeographical traits, such as migratory habits or phylogeographical history, on ecological networks is poorly understood. Meta-networks, i.e., networks that cover large spatial extensions and include species not co-occurring locally, enable us to investigate mechanisms that operate at larger spatial scales such as migratory patterns or phylogeographical distributions, as well as indirect relationships among species through shared partners. Using a meta-network of hummingbird-plant interaction across Mexico, we illustrate the usefulness of this approach by investigating (1) how biogeographical and morphological factors associate with observed interactions and (2) how species-specific biogeographical characteristics associate with species’ network roles. Our results show that all studied hummingbird and plant species in the meta-network were interrelated, either directly or through shared partners. The meta-network was structured into modules, resulting from hummingbirds and plants interacting preferentially with subsets of species, which differed in biogeographical, and, to a lesser extent, morphological traits. Furthermore, migrants and hummingbirds from Nearctic, Transition, and widespread regions had a higher topological importance in the meta-network. Our study illustrates how meta-networks may contribute to our current knowledge on species’ biogeographical traits and biotic interactions, providing a perspective complementary to local-scale networks.  相似文献   
26.
27.

Climate change is a global phenomenon that affects biophysical systems and human well-being. The Paris Agreement of the United Nations Framework Convention on Climate Change entered into force in 2016 with the objective of strengthening the global response to climate change by keeping global temperature rise this century well below 2 °C above pre-industrial levels and to pursue efforts to limit the temperature increase even further to 1.5 °C. The agreement requires all Parties to submit their “nationally determined contributions” (NDCs) and to strengthen these efforts in the years ahead. Reducing carbon emissions from deforestation and forest degradation is an important strategy for mitigating climate change, particularly in developing countries with large forests. Extensive tropical forest loss and degradation have increased awareness at the international level of the need to undertake large-scale ecological restoration, highlighting the need to identify cases in which restoration strategies can contribute to mitigation and adaptation. Here we consider Brazil as a case study to evaluate the benefits and challenges of implementing large-scale restoration programs in developing countries. The Brazilian NDC included the target of restoring and reforesting 12 million hectares of forests for multiple uses by 2030. Restoration of native vegetation is one of the foundations of sustainable rural development in Brazil and should consider multiple purposes, from biodiversity and ecosystem services conservation to social and economic development. However, ecological restoration still presents substantial challenges for tropical and mega-diverse countries, including the need to develop plans that are technically and financially feasible, as well as public policies and monitoring instruments that can assess effectiveness. The planning, execution, and monitoring of restoration efforts strongly depend on the context and the diagnosis of the area with respect to reference ecosystems (e.g., forests, savannas, grasslands, wetlands). In addition, poor integration of climate change policies at the national and subnational levels and with other sectorial policies constrains the large-scale implementation of restoration programs. The case of Brazil shows that slowing deforestation is possible; however, this analysis highlights the need for increased national commitment and international support for actions that require large-scale transformations of the forest sector regarding ecosystem restoration efforts. Scaling up the ambitions and actions of the Paris Agreement implies the need for a global framework that recognizes landscape restoration as a cost-effective nature-based solution and that supports countries in addressing their remaining needs, challenges, and barriers.

  相似文献   
28.
The mountain chain of the Sierra Madre de Chiapas in southern Mexico is globally significant for its biodiversity and is one of the most important coffee production areas of Mexico. It provides water for several municipalities and its biosphere reserves are important tourist attractions. Much of the forest cover outside the core protected areas is in fact coffee grown under traditional forest shade. Unless this (agro)forest cover can be sustained, the biodiversity of the Sierra Madre and the environmental services it provides are at risk. We analyzed the threats to livelihoods and environment from climate change through crop suitability modeling based on downscaled climate scenarios for the period 2040 to 2069 (referred to as 2050s) and developed adaptation options through an expert workshop. Significant areas of forest and occasionally coffee are destroyed every year by wildfires, and this problem is bound to increase in a hotter and drier future climate. Widespread landslides and inundations, including on coffee farms, have recently been caused by hurricanes whose intensity is predicted to increase. A hotter climate with more irregular rainfall will be less favorable to the production of quality coffee and lower profitability may compel farmers to abandon shade coffee and expand other land uses of less biodiversity value, probably at the expense of forest. A comprehensive strategy to sustain the biodiversity, ecosystem services and livelihoods of the Sierra Madre in the face of climate change should include the promotion of biodiversity friendly coffee growing and processing practices including complex shade which can offer some hurricane protection and product diversification; payments for forest conservation and restoration from existing government programs complemented by private initiatives; diversification of income sources to mitigate risks associated with unstable environmental conditions and coffee markets; integrated fire management; development of markets that reward sustainable land use practices and forest conservation; crop insurance programs that are accessible to smallholders; and the strengthening of local capacity for adaptive resource management.  相似文献   
29.
The European Union Water Framework Directive (WFD) aims to achieve the “good status” of waters by 2015, through monitoring and control of human impacts on “bodies of surface water” (BSWs), discrete elements for quality diagnosis and management. Headwater streams, however, are frequently neglected as they are not usually recognised as BSW. This poses limitations for the management of river catchments, because anthropogenic impacts on headwaters can constrain the quality of downstream rivers. To illustrate this problem, we compared nitrate levels and land use pressures in a small agricultural catchment with those recorded in the catchment in which it is embedded (Ega), and in the Ebro River Basin (NE Spain) comprising both. Agriculture greatly influenced water nitrate concentration, regardless of the size of the catchments: R2 = 0.91 for headwater catchments (0.1–7.3 km2), and R2 = 0.82 for Ebro tributary catchments (223–3113 km2). Moreover, nitrate concentration in the outlet of a non-BSW small river catchment was similar to that of the greater downstream BSW rivers. These results are of interest since, despite representing 76% of the length of the Ega catchment hydrographical network, only 3.1% of the length of the headwater streams has been identified as BSWs. Human activities affecting headwater streams should therefore be considered if the 2015 objective of the WFD is to be achieved.  相似文献   
30.
Flower colour is an important signal used by flowering plants to attract pollinators. Many anthophilous insects have an innate colour preference that is displayed during their first foraging bouts and which could help them locate their first nectar reward. Nevertheless, learning capabilities allow insects to switch their colour preferences with experience and thus, to track variation in floral nectar availability. Manduca sexta, a crepuscular hawkmoth widely studied as a model system for sensory physiology and behaviour, visits mostly white, night-blooming flowers lacking UV reflectance throughout its range in the Americas. Nevertheless, the spectral sensitivity of the feeding behaviour of naïve moths shows a narrow peak around 450 nm wavelengths, suggesting an innate preference for the colour blue. Under more natural conditions (i.e. broader wavelength reflectance) than in previous studies, we used dual choice experiments with blue- and white-coloured feeders to investigate the innate preference of naïve moths and trained different groups to each colour to evaluate their learning capabilities. We confirmed the innate preference of M. sexta for blue and found that these moths were able to switch colour preferences after training experience. These results unequivocally demonstrate that M. sexta moths innately prefer blue when presented against white flower models and offer novel experimental evidence supporting the hypothesis that learning capabilities could be involved in their foraging preferences, including their widely observed attraction to white flowers in nature.  相似文献   
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