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271.
Many socially monogamous bird species follow a genetically promiscuous reproductive strategy. Duetting birds may be an exception, as they appear to exhibit very low levels of extra pair paternity—which is thought to be connected to duetting. Duets are predicted to function either in paternity guarding or as signals of commitment to the pair bond, reciprocally reducing extra pair mating in both sexes. In this study, we used four microsatellites to document paternity loss in the Crimson-breasted Shrike (Laniarius atrococcineus), a socially monogamous subtropical duetting species. Extra pair paternity was surprisingly high, with extra pair males siring 20 % of young in 30 % of broods. Furthermore, we compared the levels of extra pair paternity of each pair to certain characteristics of their duets to test the paternity guard and the commitment hypotheses. Our results offered no support that duets function in paternity guarding, although the fact that males which had been cuckolded answered more of their female’s calls could represent an adaptation to avoid future cuckoldry. We also found no evidence for duets functioning as signal of commitment. Female vocal behaviour was in fact the reverse of that predicted: Levels of infidelity amongst social females were positively related to female answer rate of their mates’ songs. These results indicate that females may use increased answer rates as a form of manipulation, in an attempt to avoid potential costs associated with their extra pair matings.  相似文献   
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The flux of organic particles below the mixed layer is one major pathway of carbon from the surface into the deep ocean. The magnitude of this export flux depends on two major processes—remineralization rates and sinking velocities. Here, we present an efficient method to measure sinking velocities of particles in the size range from approximately 3–400?μm by means of video microscopy (FlowCAM?). The method allows rapid measurement and automated analysis of mixed samples and was tested with polystyrene beads, different phytoplankton species, and sediment trap material. Sinking velocities of polystyrene beads were close to theoretical values calculated from Stokes’ Law. Sinking velocities of the investigated phytoplankton species were in reasonable agreement with published literature values and sinking velocities of material collected in sediment trap increased with particle size. Temperature had a strong effect on sinking velocities due to its influence on seawater viscosity and density. An increase in 9?°C led to a measured increase in sinking velocities of ~40?%. According to this temperature effect, an average temperature increase in 2?°C as projected for the sea surface by the end of this century could increase sinking velocities by about 6?% which might have feedbacks on carbon export into the deep ocean.  相似文献   
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Comparison of forest protection between regions in Europe is extremely difficult, because there is such wide variation of strategies, procedures and constraints; the way forests have been used historically and their present closeness to nature also varies, and furthermore so does the definition of what constitutes a forest. For the European Ministerial Conference on the Protection of Forests in Europe (MCPFE) in 2003, forest protection has been harmonised into three categories for the sake of comparison: protection to safeguard biodiversity, protection of landscape and specific natural features, and protective forest functions.There is no single, uniform and universal model and no internationally agreed target with respect to the percentage of forests which should be protected. What is more important than a fixed percentage level of forested area (e.g. 5 or 10%) is that the protection network should be biogeographically and ecologically representative and accordingly distributed on a regional basis. Long-term practical experience and research have proved that conservation of different species of organisms can be assured by appropriate silvicultural management of multifunctional production forests. Consequently, the focus of debate in Europe appears to shift more and more from total protection in segregated areas to 'precision protection' and to combining protection and timber production in the holistic, integrated concept of modern management of forest areas.Advances in regional ecological planning and the growing adoption of naturalistic forest management practices have slowed the decline of the biological diversity in the multifunctional production forests. However, this fact is not yet widely and sufficiently acknowledged and appreciated. There is consequently a political and scientific need for continued study of the effects of naturalistic silvicultural management on the biodiversity of forests. Information from such research is crucially needed before new and additional protection networks and schemes are set up on a large-scale. Protection by voluntary contracts between parties is a workable model concept for European forestry based on private forest ownership. In small private forests, patches of forest worth protecting are often small and located within production forests.Forest certification can contribute to the efforts of maintaining biodiversity in multifunctional production forests and offers an instrument of independently monitoring and verifying that forests are managed according to the agreed criteria. Forest certification is not an alternative or a means of increasing forest protection, because as a voluntary process it cannot guarantee the permanence of protected areas or deal with issues of finance and compensation.  相似文献   
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