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The inner ear in the group of archosaurs (birds, crocodilians, and extinct dinosaurs) shows a high degree of structural similarity,
enabling predictions of their function in extinct species based on relationships among similar variables in living birds.
Behavioral audiograms and morphological data on the length of the auditory sensory epithelium (the basilar papilla) are available
for many avian species. By bringing different data sets together, we show that body mass and the size of the basilar papilla
are significantly correlated, and the most sensitive frequency in a given species is inversely related to the body mass and
the length of the basilar papilla. We also demonstrate that the frequency of best hearing is correlated with the high-frequency
limit of hearing. Small species with a short basilar papilla hear higher frequencies compared with larger species with a longer
basilar papilla. Based on the regression analysis of two significant correlations in living archosaurs (best audiogram frequency
vs body mass and best audiogram frequency vs papillar length), we suggest that hearing in large dinosaurs was restricted to
low frequencies with a high-frequency limit below 3 kHz.
Supplementary material is available in the online version of this article at and accessible for authorised users. 相似文献
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The origin and early evolution of birds: discoveries,disputes, and perspectives from fossil evidence 总被引:1,自引:0,他引:1
Zhou Z 《Die Naturwissenschaften》2004,91(10):455-471
The study of the origin and early evolution of birds has never produced as much excitement and public attention as in the past decade. Well preserved and abundant new fossils of birds and dinosaurs have provided unprecedented new evidence on the dinosaurian origin of birds, the arboreal origin of avian flight, and the origin of feathers prior to flapping flight. The Mesozoic avian assemblage mainly comprises two major lineages: the prevalent extinct group Enantiornithes, and the Ornithurae, which gave rise to all modern birds, as well as several more basal taxa. Cretaceous birds radiated into various paleoecological niches that included fish- and seed-eating. Significant size and morphological differences and variation in flight capabilities, ranging from gliding to powerful flight among early birds, highlight the diversification of birds in the Early Cretaceous. There is little evidence, however, to support a Mesozoic origin of modern avian groups. Controversy and debate, nevertheless, surround many of these findings, and more details are needed to give a better appreciation of the significance of these new discoveries. 相似文献
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Ultraviolet (UV) reflectance of the plumage is common in birds and plays an important role in sexual signalling. Recently,
it has been proposed that birds are able to modify plumage UV reflectance by the application of uropygial gland secretion.
Based on a survey of the optical properties of this secretion from 51 species belonging to 12 avian orders, we show that two
main types of uropygial secretions exist, one predominantly found in passerines and one in non-passerines, both reducing relative
UV reflectance of a white background (Teflon™ tape). We quantified how each type of secretion (exemplified by blue tit and
mallard) affected feather UV reflectance. Both secretions reduced overall brightness and relative UV reflectance of white
mallard feathers but hardly affected the reflectance of UV/blue blue tit crown feathers. According to models of avian colour
vision, changes in reflectance due to application of the secretion were at or below the discrimination threshold of most birds.
We conclude that the uropygial secretion is unlikely to play a major role in modifying plumage UV reflectance. However, the
optical properties of the uropygial secretion may have been selected to interfere as little as possible with visual signaling
through plumage reflectance.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
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Cognitive skills and bacterial load: comparative evidence of costs of cognitive proficiency in birds
Soler JJ Peralta-Sánchez JM Martín-Vivaldi M Martín-Platero AM Flensted-Jensen E Møller AP 《Die Naturwissenschaften》2012,99(2):111-122
Parasite-mediated selection may affect the evolution of cognitive abilities because parasites may influence development of
the brain, but also learning capacity. Here, we tested some predictions of this hypothesis by analyzing the relationship between
complex behaviours (feeding innovations (as a measure of behavioural flexibility) and ability to detect foreign eggs in their
nests (i.e. a measure of discriminatory ability)) and abundance of microorganisms in different species of birds. A positive
relationship would be predicted if these cognitive abilities implied a larger number of visited environments, while if these
skills favoured detection and avoidance of risky environments, a negative relationship would be the prediction. Bacterial
loads of eggshells, estimated for mesophilic and potentially pathogenic bacteria (i.e. Enterococcus, Staphylococcus and Enterobacteriaceae), were used as a surrogate of probability of contact with pathogenic bacteria. We found that bird species with higher feeding
innovation rates and rejection rates of experimental brood parasitic eggs had higher density of bacteria on their eggshells
than the average species. Since the analysed groups of microorganisms include pathogenic bacteria, these results suggest that
both feeding innovation and ability to recognize foreign eggs are costly and highlight the importance of parasite-mediated
selection in explaining the evolution of cognitive abilities in animals. 相似文献
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Zhao Zhibo Yuan Tian Shi Xunpeng Zhao Lingdi 《Mitigation and Adaptation Strategies for Global Change》2020,25(7):1363-1380
Mitigation and Adaptation Strategies for Global Change - Global change caused by carbon emissions alone has become a common challenge for all countries. However, current debates about urbanization... 相似文献
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This paper analyses social constraints influencing air quality governance in four European Union (EU) countries. The comparative analysis carried out here is the outcome of the EU FP7 SEFIRA project. Starting from study of implemented measures the paper marks out the structure of double-delegation in policy-making for air quality governance; that is to say the delegation from the EU to national governments who further delegate to regional and local authorities the burden to put in place concrete measures. Therefore, our analysis has followed a multi-level approach considering all the territorial level down to the urban scale. In doing so, we found out commonalities in the strategies which have been followed by policy-makers. The comparison has been made possible through the analysis of operationalised categories such as Domain, Objectives and Modalities on air quality plans. The analysis went further: through interviews with selected key stakeholder the social constraints which may limit the choices made by institutions have been investigated. The -lack of- success in attaining EU requirements for the air quality cannot be considered only as the outcome of the −lack of- awareness of which may be the best practices or choices, rather as the result of complex entanglements of social forces. Indeed, one of the main outcomes of this explorative investigation has been the breakdown of such complexity into its social component in a comparative study. The paper finally points out the need to promote an integrated approach for air quality policy as a strategy for the design of new measures for the future. 相似文献
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Light-dependent magnetoreception in birds: the effect of intensity of 565-nm green light 总被引:1,自引:0,他引:1
In a previous study, Australian silvereyes tested in autumn under monochromatic 565-nm green light at intensities of 2.1
and 7.5 mW m–2 preferred their normal northerly migratory direction, whereas they showed a significantly different tendency towards northwest
at 15.0 mW m–2. Repeating these experiments in spring with silvereyes migrating southward, we again observed well-oriented tendencies in
the migratory direction at 2.1 and 7.5 mW m–2. At 15.0 mW m–2, however, the birds once more preferred northwesterly directions, i.e. their response under this condition proved to be independent
of the migratory direction. This contradicts the interpretation that monochromatic green light of this high intensity leads
to a rotation of compass information; instead, it appears to produce sensory input that causes birds to give up their migratory
direction in favor of a fixed direction of as yet unknown origin.
Received: 3 April 2000 / Accepted in revised form: 19 June 2000 相似文献
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Bushmeat market data can be used to detect hunting sustainability by using proxies such as decline in sale volume and price increases over time. Here, we explore these proxies for the Malabo market in Bioko Island, Equatorial Guinea, the main bushmeat sale centre for the island. We gathered data during two sample phases (we call these ‘early’ and ‘later’) between March 1996 and October 1998, to test for evidence of faunal depletion during that period. Mammals (ungulates, rodents and primates) made up most of the bushmeat sold. Our analyses confirmed significant and sudden, rather than continuous, declines between phases, in total and individual animal group carcass volumes. Market species composition differed between phases; diversity indices and evenness increased in the later phase of the study. Price was related to species body mass and carcass condition (whether the carcass was smoked or fresh). Most species prices were higher in the later phase of the study. A total of 33 sites contributed bushmeat to the market, with over half of the recorded volume emerging from five sites in the south of the island. Bushmeat volume supplied from different regions of the island varied significantly between phases, and fewer sites contributed animals to the market during the later phase of the study. Proportionately more primates, ungulates but fewer rodents, appeared in the southern samples, compared with the northern. We suggest that in just over 2 years, hunting incursions, especially into the south of the island, may have resulted in drastic faunal losses. Subsequent data, collected by other authors, also indicate that the hunting spurt in the mid- and late-1990s may have irreversibly imperilled the island's mammalian fauna, since numbers of these animals entering the market have not increased since our study period. Although the Equato-Guinean authorities have recently initiated mechanisms to better protect the country's wildlife, through various legal and funding instruments, we suggest that these initiatives are likely to fail, if the social and environmental linkages are not fully understood to guide immediate restoration of such a unique African faunal assemblage. 相似文献
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In the last few decades, the international insurance industry has been confronted with a drastic increase in the scope and frequency of great natural disasters. The trend is primarily attributable to the continuing steady growth of the world population and the increasing concentration of people and economic values in urban areas. An additional factor is the global migration of populations and industries into areas such as coastal regions, which are particularly exposed to natural hazards. The natural hazards themselves, on the other hand, are showing a change for the worse as many atmospheric extremes are strongly influenced by global warming. In addition to the problems the insurance industry has with regard to pricing, capacity and loss reserves, the assessment of insured liabilities, preventive planning and the proper adjustment of catastrophe losses are gaining importance. The present problems will be dramatically aggravated if the greenhouse predictions come true. The changing probability distributions of many processes in the atmosphere will force up the frequency and severity of heat waves, droughts, bush fires, tropical and extratropical cyclones, tornados, hailstorms, floods and storm surges in many parts of the world with serious consequences for all types of property insurance, apart from the consequences of the stratospheric ozone destruction for health and life insurance. Rates will have to be raised and in certain areas insurance cover will only be available after considerable restrictions have been imposed, as for example significant deductibles and low liability or loss limits. In areas of high insurance density the loss potential of individual catastrophes can reach a level at which the national and international insurance industries will run into serious capacity problems. Recent disasters showed the disproportionately high participation of reinsurers in extreme disaster losses and the need for more risk transparency if the insurance industry is to fulfil its obligations in an increasingly hostile environment. 相似文献
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Death in fishing gear of non-target species (called ‘bycatch’) is a major concern for marine wildlife, and mostly worrying for long-lived species like cetaceans, considering their demographic characteristics (slow population growth rates and low fecundity). In European waters, cetaceans are highly impacted by this phenomenon. Under the Common Fishery Policy, the EC 812/2004 regulation constitutes a legal frame for bycatch monitoring on 5–10% of fishing vessels >15 m. The aim of this work was to compare parameters and bycatch estimates of common dolphins (Delphinus delphis) provided by observer programmes in France and UK national reports and those inferred from stranding data, through two approaches. Bycatch was estimated from stranding data, first by correcting effectives from drift conditions (using a drift prediction model) and then by estimating the probability of being buoyant. Observer programmes on fishing vessels allowed us to identify the specificity of the interaction between common dolphins and fishing gear, and provided low estimates of annual bycaught animals (around 550 animals year−1). However, observer programmes are hindered by logistical and administrative constraints, and the sampling scheme seems to be poorly designed for the detection of marine mammal bycatches. The analyses of strandings by considering drift conditions highlighted areas with high levels of interactions between common dolphins and fisheries. Since 1997, the highest densities of bycaught dolphins at sea were located in the southern part of the continental shelf and slope of the Bay of Biscay. Bycatch numbers inferred from strandings suggested very high levels, ranging from 3650 dolphins year−1 [2250–7000] to 4700 [3850–5750] dolphins year−1, depending on methodological choices. The main advantage of stranding data is its large spatial scale, cutting across administrative boundaries. Diverging estimates between observer programmes and stranding interpretation can set very different management consequences: observer programmes suggest a sustainable situation for common dolphins, whereas estimates based on strandings highlight a very worrying and unsustainable process. 相似文献
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Tas Thamo David J. Pannell Marit E. Kragt Michael J. Robertson Maksym Polyakov 《Mitigation and Adaptation Strategies for Global Change》2017,22(7):1095-1111
Accurate assessment of the cost of carbon sequestration is important for the development of mitigation policies globally. Given that sequestration in soils or vegetation is a lengthy process, such assessment requires financial discounting and making realistic assumptions about changes over time in the rate of sequestration, the price of carbon, and the opportunity cost incurred by adopting sequestration practices. Our objective is to demonstrate how these assumptions affect estimates of the cost of sequestration-based mitigation strategies. Using an Australian case study of soil carbon sequestration, our estimates of the carbon price required for financial viability are highly sensitive to dynamic assumptions, varying by a factor of four with different assumptions. Yet the influence of these time-related assumptions is poorly acknowledged in the literature, with many studies either failing to disclose their assumptions, or employing questionable assumptions and methods. Recommended global strategies are for researchers to report their assumptions related to dynamics much more transparently and to improve their research methods and the realism of their assumptions when analysing the economics of carbon sequestration. We recommend that policymakers become better aware of the issues created by dynamics, so that they are able to validly interpret assessments of the cost of sequestration and to ensure that they design policies in a way that facilitates fair comparison of the costs of mitigation strategies that operate over different timescales. 相似文献
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Robin B. Matthews Meine van Noordwijk Eric Lambin Patrick Meyfroidt Joyeeta Gupta Louis Verchot Kristell Hergoualc’h Edzo Veldkamp 《Mitigation and Adaptation Strategies for Global Change》2014,19(6):907-925
The REDD-ALERT (Reducing Emissions from Deforestation and Degradation from Alternative Land Uses in the Rainforests of the Tropics) project started in 2009 and finished in 2012, and had the aim of evaluating mechanisms that translate international-level agreements into instruments that would help change the behaviour of land users while minimising adverse repercussions on their livelihoods. Findings showed that some developing tropical countries have recently been through a forest transition, thus shifting from declining to expanding forests at a national scale. However, in most of these (e.g. Vietnam), a significant part of the recent increase in national forest cover is associated with an increase in importation of food and timber products from abroad, representing leakage of carbon stocks across international borders. Avoiding deforestation and restoring forests will require a mixture of regulatory approaches, emerging market-based instruments, suasive options, and hybrid management measures. Policy analysis and modelling work showed the high degree of complexity at local levels and highlighted the need to take this heterogeneity into account—it is unlikely that there will be a one size fits all approach to make Reducing Emissions from Deforestation and Degradation (REDD+) work. Significant progress was made in the quantification of carbon and greenhouse gas (GHG) fluxes following land-use change in the tropics, contributing to narrower confidence intervals on peat-based emissions and their reporting standards. There are indications that there is only a short and relatively small window of opportunity of making REDD+ work—these included the fact that forest-related emissions as a fraction of total global GHG emissions have been decreasing over time due to the increase in fossil fuel emissions, and that the cost efficiency of REDD+ may be much less than originally thought due to the need to factor in safeguard costs, transaction costs and monitoring costs. Nevertheless, REDD+ has raised global awareness of the world’s forests and the factors affecting them, and future developments should contribute to the emergence of new landscape-based approaches to protecting a wider range of ecosystem services. 相似文献
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Dietary characterization of the hominoid Khoratpithecus (Miocene of Thailand): evidence from dental topographic and microwear texture analyses 总被引:1,自引:0,他引:1
The genus Khoratpithecus, a hominoid thought to be related to the orangutan lineage, is represented by two known fossil species K. chiangmuanensis and K. piriyai. Both were discovered in Southeast Asia (Thailand) and are dated to the Middle and Late Miocene, respectively. In this study, dental topographic and microwear texture analyses were used to examine molars from both of these species, with the goal of understanding their dietary preferences. Although sample sizes are small for Khoratpithecus, available data are compared to that collected for extant apes. Environmental evidence, such as botanical remains and sedimentological data, is also considered for comparisons with dietary reconstruction. Results from dental topographic analysis suggest that the two fossil species were better adapted to a diet of fruits than to one of leaves, much like the living orangutan or chimpanzee. Results from microwear texture analysis further support this, suggesting that Khoratpithecus preferred soft fruits to hard fruits or seeds. And finally, the botanical and sedimentological evidence point to environments for Khoratpithecus that would have been compatible with a fruit-eating species. Given the small sample sizes available for analysis, however, definitive judgments are not yet possible at this time. 相似文献