首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到13条相似文献,搜索用时 15 毫秒
1.
Aim To reconstruct the flora, vegetation, climate and palaeoaltitude during the Miocene (23.03–5.33 Ma) in Central Europe. Location Six outcrop sections located in different basins of the Central Paratethys in Austria. Methods Pollen analysis was used for the reconstruction of the vegetation and climate. The altitude of the Eastern Alps that are adjacent to the Alpine Foreland and Vienna basins has been estimated using a new quantification method based on pollen data. This method uses biogeographical and climatological criteria such as the composition of the modern vegetation belts in the European mountains and Miocene annual temperature estimates obtained from fossil pollen data. Results Pollen changes from Early to Late Miocene have been observed. The vegetation during the Burdigalian and Langhian (20.43–13.65 Ma) was dominated by thermophilous elements such as evergreen trees, typical of a present‐day evergreen rain forest at low altitudes (i.e. south‐eastern China). During the Serravallian and Tortonian (13.65–7.25 Ma) several thermophilous elements strongly decreased, and some disappeared from the Central European region. This kind of vegetation was progressively substituted by one enriched in deciduous and mesothermic plants. Middle‐altitude (Cathaya, Cedrus and Tsuga) and high‐altitude (Abies and Picea) conifers increased considerably during the Langhian and later on during the Serravallian and Tortonian. Main conclusions Pollen changes are related to climatic changes and to the uplift of the Alpine massifs. The vegetation during the Burdigalian and Langhian reflects the Miocene climatic optimum. The decrease in thermophilous plants during the Serravallian and Tortonian can be interpreted as a climatic cooling and can be correlated with global and regional climatic changes. This study shows that the palaeoaltitude of the eastern part of the Eastern Alps during the Burdigalian was not high enough for Abies and Picea to form a forest. Therefore, we inferred that the summits of most of the mountains would have been less than 1800 m. The substantial increase of middle‐ and high‐altitude conifers in the pollen spectra suggests that the uplift rate increased during the Langhian in this region. Based on higher palaeoaltitude estimations for the pollen floras from the studied sections of Austria, we infer that the uplift of the easternmost part of the Alpine chain continued during the Serravallian and Tortonian.  相似文献   

2.
Aim African–Asian disjunctions are common in palaeotropical taxa, and are typically explained by reference to three competing hypotheses: (1) ‘rafting’ on the Indian tectonic plate, enabling Africa‐to‐Asia dispersal; (2) migration via Eocene boreotropical forests; and (3) transoceanic long‐distance dispersal. These hypotheses are tested using Uvaria (Annonaceae), which is distributed in tropical regions of Africa, Asia and Australasia. Recent phylogenetic reconstructions of the genus show a clear correlation with geographical provenance, indicating a probable origin in Africa and subsequent dispersal to Asia and then Australasia. Ancestral areas and migration routes are inferred and compared with estimates of divergence times in order to distinguish between the prevailing dispersal hypotheses. Location Palaeotropics. Methods Divergence times in Uvaria are estimated by analysing the sequences of four DNA regions (matK, psbA–trnH spacer, rbcL and trnL–F) from 59 Uvaria species and 77 outgroup species, using a Bayesian uncorrelated lognormal (UCLD) relaxed molecular clock. The ancestral area of Uvaria and subsequent dispersal routes are inferred using statistical dispersal–vicariance analysis (s‐diva ). Results Uvaria is estimated to have originated in continental Africa 31.6 Ma [95% highest posterior density (HPD): 38.4–25.1 Ma] between the Middle Eocene and Late Oligocene. Two main migration events during the Miocene are identified: dispersal into Madagascar around 17.0 Ma (95% HPD: 22.3–12.3 Ma); and dispersal into Asia between 21.4 Ma (95% HPD: 26.7–16.7 Ma) and 16.1 Ma (95% HPD: 20.1–12.1 Ma). Main conclusions Uvaria fruits are widely reported to be consumed by primates, and are therefore unlikely candidates for successful long‐distance transoceanic dispersal. The other biogeographical hypotheses, involving rafting on the Indian tectonic plate, and dispersal via the European boreotropical forests associated with the Eocene thermal maximum, can be discounted due to incongruence with the divergence time estimates. An alternative scenario is suggested, involving dispersal across Arabia and central Asia via the tropical forests that developed during the late Middle Miocene thermal maximum (17–15 Ma), associated with the ‘out‐of‐Africa’ dispersal of primates. The probable route and mechanism of overland dispersal between Africa and Asia for tropical plant groups during the Miocene climatic optimum are clarified based on the Uvaria data.  相似文献   

3.
Recent single-unit recording studies have clarified how multiple parameters of movement are signaled by individual cortical and cerebellar neurons, and also that multiple coordinate frames are utilized. Cognitive processes also modulate the firing of these neurons. The various signals and coordinate systems vary in time and evolve throughout a behavioral sequence, consistent with the demands of the task and the required sensorimotor transformations.  相似文献   

4.
The Mokrá-Western Quarry exhibits the rare occurrence of Early Miocene (MN 4) vertebrate fauna within the area of the eastern part of Central Europe. In addition to a rich fauna of reptiles and mammals, two fossiliferous karst joints (Mokrá-Western Quarry, 1/2001 Turtle Joint and Mokrá-Western Quarry, 2/2003 Reptile Joint) yielded a rich fauna of amphibians including 13 amphibian taxa: Salamandridae: Mioproteus sp., Chelotriton sp., type I, Chelotriton sp., type II, Triturus aff. roehrsi, Triturus cf. marmoratus, Triturus sp. (T. cristatus species group), Chioglossa meini, Mertensiella mera, Salamandridae gen. and sp. indet.; Pelobatidae: Pelobates sanchizi; Ranidae: Rana sp. (synklepton Rana esculenta); Bufonidae: Bufo sp. The first records of the West European species Triturus cf. marmoratus and Chioglossa meini are reported from the eastern part of Central Europe indicating the wide distribution of those taxa throughout the whole of Europe as early as MN 4. The oldest known record of Pelobates sanchizi documents the Early Miocene presence of representatives closely related to the extinct Late Oligocene representatives of Pelobates. The slow evolution of amphibian species is documented by the presence of Triturus cf. marmoratus and the oldest known occurrence of the extinct salamander Mertensiella mera.  相似文献   

5.
The palynological analysis of the Burdigalian (Early Miocene) successions of the Güvem Basin (NW Central Anatoia, Turkey) has been carried out with the aim of reconstructing the palaeovegetation. The pollen spectra indicate a flora dominated by trees such as Quercus deciduous type, Carya, Carpinus, Ulmus/Zelkova, Engelhardia, Quercus ilex type and Pinaceae. Pterocarya, Juglans, Alnus, Salix, Liquidambar and Oleaceae are represented by lower percentages. Herbs and shrubs are represented by minor amounts of Poaceae, Amaranthaceae/Chenopodiaceae, Asteraceae/Asteroideae, Brassicaceae, and the aquatics Potamogeton, Sparganium and Typha. The Burdigalian flora reflects a mixed mesophytic forest with Quercus deciduous type, Quercus ilex type, pine species, Ulmus/Zelkova, Engelhardia, Carya, Carpinus, Pterocarya, etc., sparcely interspersed with open herbaceous areas. This flora reflects a warm-temperate climate. The fluctuations in abundances of broadleaved trees and xerophytes may represent fluctuations of relatively wet and dry periods. The overall composition of the flora of the Güvem Basin reflects cooler conditions compared with other Early Miocene floras in Europe, which is possibly due to intense volcanic activity of the area.  相似文献   

6.
By promoting the biological recruitment of relevant natural resources, wetlands offer a major ecosystem service. This study investigates the importance of wetland habitats of the central Amazon basin as sites for spawning and/or initial development of seven of the most important commercial Characiforms fish species. In order to confirm this importance, samples of the eggs, larvae, and juveniles of these fish species were collected during the four seasonal phases of the hydrological cycles of 2010 and 2011, in different aquatic environments of the wetland ecosystem in the central Amazon. The results confirmed that the flooding phase is the most important for the spawning of these species, and that they preferred to use the marginal areas of the central Amazon as spawning grounds. The larvae of these species colonize the confluence zone of the rivers and the mouths of the floodplain channels, principally during the initial stages (pre-flexion) of their ontogenetic development. The channels that connect the lakes to the rivers are the main dispersal route for the larvae, especially those in advanced stages of development (flexion/post-flexion), towards the internal of the wetland habitats, such as the lakes and large mattresses of floating vegetation. The different wetland habitats of this region provide an extremely important ecosystem service, playing a critical role in the recruitment of commercially-valuable fish species, and thus require adequate protection and management to ensure the continuity of fisheries and natural stocks.  相似文献   

7.
Primate fossil assemblages often have metacarpals and phalanges from which functional/behavioral interpretations may be inferred. For example, intrinsic hand proportions can indicate hand function and substrate use. But, estimates of intrinsic hand proportions from unassociated hand elements can be imperfect due to digit misattribution. Although isolated metacarpals can be identified to a specific digit, phalanges are difficult to assign to a specific ray. We used a resampling approach to evaluate how estimates of intrinsic hand proportions are affected by such uncertainty. First, the phalangeal index—intermediate phalanx length plus proximal phalanx length divided by metacarpal length—for the third digit was calculated for associated specimens of terrestrial, semiterrestrial, and arboreal taxa. We then used resampling procedures to generate distributions of “composite digits” based on resampled ratios in which phalanges from the second, fourth, and fifth rays, and from different individuals, were chosen randomly. Results confirm that the phalangeal index for associated third digits significantly discriminates groups. We also found that resampled ratios had significantly lower means, indicating that using composite digits is prone to systematic underestimation. Resampled ratios also generated distributions with greater variance around the means that obscured distinctions between groups, although significant differences between the most arboreal and terrestrial taxa are maintained. We conclude that using unassociated phalanges to calculate a phalangeal index is prone to sampling bias. Nevertheless, a resampling approach has the potential to inform estimates of hand proportions for fossil taxa, provided that the comparative sample is constrained to mimic the fossil composition. Am J Phys Anthropol 151:280–289, 2013. © 2013 Wiley Periodicals, Inc.  相似文献   

8.
S. Toepfer  U. Kuhlmann 《BioControl》2004,49(4):385-395
The western corn rootworm, Diabrotica virgifera virgifera LeConte(Coleoptera: Chrysomelidae), is the mostdestructive pest of maize (Zea mays L.)in North America, and began to successfullyinvade Central Europe in the early 1990's. Thispaper reports a three-year field surveyconducted in Hungary, Yugoslavia, and Croatia,which are currently the focal points ofinvasion, with the aim to determine theoccurrence of indigenous natural enemies ofD. v. virgifera in Europe. A total of9,900 eggs, 550 larvae, 70 pupae and 33,000adults were examined for the occurrence ofparasitoids, nematodes, and fungal pathogens. It can be concluded from the survey resultsthat effective indigenous natural enemies arenot attacking any of the life stages of D.v. virgifera in Europe. The exception is theoccurrence of the fungi Beauveriabassiana (Bals.) Vuill. (Mitosporic fungi;formerly Deuteromyces) and Metarhiziumanisopliae (Metsch.) Sorok (Mitosporic fungi)attacking adults of D. v. virgifera at anextremely low level (< 1%). However no otherentomopathogenic fungal pathogens,entomopathogenic nematodes, or parasitoids werefound on eggs, larvae, pupae or adults. Whileseveral natural enemies in North and CentralAmerica are known to attack D. v.virgifera, it is apparent that indigenousnatural enemies in Europe have not adapted tothe high population density of the alieninvasive species D. v. virgifera. Classical biological control may provide anopportunity to reconstruct the natural enemycomplex of an invading alien pest, and itsapplication to manage D. v. virgiferapopulations in Europe should be considered.  相似文献   

9.
Retention forestry, which retains a portion of the original stand at the time of harvesting to maintain continuity of structural and compositional diversity, has been originally developed to mitigate the impacts of clear‐cutting. Retention of habitat trees and deadwood has since become common practice also in continuous‐cover forests of Central Europe. While the use of retention in these forests is plausible, the evidence base for its application is lacking, trade‐offs have not been quantified, it is not clear what support it receives from forest owners and other stakeholders and how it is best integrated into forest management practices. The Research Training Group ConFoBi (Conservation of Forest Biodiversity in Multiple‐use Landscapes of Central Europe) focusses on the effectiveness of retention forestry, combining ecological studies on forest biodiversity with social and economic studies of biodiversity conservation across multiple spatial scales. The aim of ConFoBi is to assess whether and how structural retention measures are appropriate for the conservation of forest biodiversity in uneven‐aged and selectively harvested continuous‐cover forests of temperate Europe. The study design is based on a pool of 135 plots (1 ha) distributed along gradients of forest connectivity and structure. The main objectives are (a) to investigate the effects of structural elements and landscape context on multiple taxa, including different trophic and functional groups, to evaluate the effectiveness of retention practices for biodiversity conservation; (b) to analyze how forest biodiversity conservation is perceived and practiced, and what costs and benefits it creates; and (c) to identify how biodiversity conservation can be effectively integrated in multi‐functional forest management. ConFoBi will quantify retention levels required across the landscape, as well as the socio‐economic prerequisites for their implementation by forest owners and managers. ConFoBi's research results will provide an evidence base for integrating biodiversity conservation into forest management in temperate forests.  相似文献   

10.
Unsown fallow plots, commonly referred to as ‘lapwing plots’, are widely promoted within the English agri-environmental programme, but remain unstudied outside of England. We tested Lapwing plots in an industrialised agricultural landscape in Central Europe from 2010 to 2015. Lapwings (Vanellus vanellus) and other birds as well as plant species were mapped. Factors influencing the success of the plots were modelled to obtain information on how to design a well-working agri-environment scheme (AES).Lapwings were present at 65% of the 61 lapwing plots studied, whereas colonisation of untreated control sites was significantly lower (37%). 64 lapwing pairs bred at 26 lapwing plots, but only 18 pairs at nine untreated sites. Hatching success was significantly higher than without treatment (24 pairs at 11 lapwing plots vs. 3 pairs at 2 control sites). Other species which benefitted from the measures were Eurasian Skylark (Alauda arvensis) and Yellow Wagtail (Motacilla flava).The modelling of key factors showed that a successful lapwing plot should be: (1) large (at least about 2 ha); (2) located at a traditional breeding site; (3) sparsely vegetated; and, (4) equipped with a shallow pool of water. Placing them in winter cereals improved hatching success.Lapwing plots at damp sites are a promising AES for lapwing conservation in industrialised agricultural landscapes in Central Europe.  相似文献   

11.
Downy willow (Salix lapponum L.) is a shrub that grows widely in the subarctic and boreal peat bogs of western Siberia and north-eastern Europe. In Poland, this glacial relic, occurring at the limits of its natural range, has the status of a critically endangered species. Due to the progressive decline in the downy willow population in Poland, a programme for active protection of this species was created, with the primary objective of reintroducing it and replenishing its existing populations. At each stage of reintroduction (from the laboratory to the acclimatization station to the natural habitats), the biometric and physiological parameters of plants were monitored to identify critical periods during the process. Parameters of chlorophyll a fluorescence, the concentrations of photosynthetic pigments, and foliar accumulation of reactive oxygen species (ROS) were used as an integral criterion for determining the functional and physiological status of S. lapponum during its reintroduction. Analysis of these criteria during successive stages of plant growth and morphogenesis revealed that at several points along the way from the laboratory to the peat bogs, the specimens created during microreproduction are exposed to the risk of impairment of their physiological condition. This is mainly associated with changes in location and growth conditions, which for plants, as sedentary organisms, may be a significant stress factor inducing photosynthesis disorders and thus oxidative stress.  相似文献   

12.
The present study considers the genetic structure and phylogeography of the smooth snake (Coronella austriaca) in Central Europe, as analyzed on the basis of 14 microsatellite markers and a 284‐bp fragment of cytochrome b. We found deep divergence between western and south‐eastern Poland, suggesting at least two different colonization routes for Central Europe, originating in at least two different refugia. The west/south‐east divide was reflected in the haplotype distribution and topology of phylogenetic trees as defined by mitochondrial DNA, and in population structuring seen in the admixture analysis of microsatellite data. The well supported western European clade suggests that another refugium might have existed. We also note the isolation‐by‐distance and moderate‐to‐pronounced structuring in the examined geographical demes. Our data fit the assumption of the recently suggested sex‐biased dispersal, in that we found a strong divide in the maternal line, as well as evidence for a small but existent gene flow based on biparentally inherited microsatellite markers. All studied populations were very similar in respect of allelic richness, observed and expected heterozygosities, and inbreeding coefficients. However, some genetic characteristics were different from those expected compared to a similar fine‐scale study of C. austriaca from Great Britain. In the present study, we observed heterozygosity deficit, high inbreeding, and low Garza–Williamson indices, suggesting a reduction in population size. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 115 , 195–210.  相似文献   

13.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号