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71.
Habitat loss via human activity has fragmented populations of the golden snub-nosed monkey (Rhinopithecus roxellana), and thus affected patterns of gene flow. We investigated in-depth a single troop in the Qinling Mountains, central China, two major histocompatibility complex (MHC) class II loci, DQA1 and DQB1, and compared the resulting data with data from troops from the wider Qinling Mountains region. We found that a novel DQB1 allele was only present in the study troop and relatively few divergent alleles at the DQA1 and DQB1 loci were present compared with the wider population. The inbreeding coefficient (Fis) at the MHC region was lower than previous measurements, which may have reflected different sampling strategies. However, R. roxellana has relatively high diversity in MHC genes, even though it has probably experienced serious past population bottlenecks and reduced gene flow between populations. We also found that some alleles present in the wider population had been lost in the study troop, and suggest that conservation management strategies be implemented to increase gene flow between troops in order to increase genetic variation.  相似文献   
72.
Summary A calciturbidite bed from the lower part of the Kieselkalk Formation (late cd II) at Wallau, eastern Rheinisches Schiefergebirge, displays ideal grading of reworked calcareous shallow-water microbiota, ranging from plurimillimetric agglutinated foraminifers and fragments of calcareous algae (Koninckopora sp.) to plurimicronic calcispheres, radiolarians and sponge spicules. Microbiota derived from all levels of the platform. Correspondingly, several carbonate microfacies types could be discerned. The early diagenetic micrite base of the turbidite preserved the anoxic basinal facies. The turbidite bed belongs to Foraminiferal Zone 15 (V3bα), theAlbaillella cartalla Zone (radiolarian chronology), and is the Lower and part of the Uppertexanus Zone (standard conodont zonation). From the few published data on foraminifers, the Kieselkalk is thought to range from Mid Viséan V2b to Late Viséan V3b gamma.  相似文献   
73.
Mangroves has been described for the whole Caribbean are in their different habitats. The island of Dominica (West Indies) has always been excluded from the distribution area due to supposed inadequated conditions for mangrove growth. However, there are small areas with proper edaphic conditions for mangal in which black mangrove (Avicennia germinans L.) and white mangrove (Laguncularia racemosa L.) has been found. Even the occurrence of an additional Avicennia species is under discussion.  相似文献   
74.
旅游环境舒适度评价及其时空分异——以杭州西湖为例   总被引:1,自引:0,他引:1  
旅游环境舒适度是影响旅游者出行决策和消费行为的重要因素,进一步影响到目的地适游期长短和旅游设施利用率。影响旅游舒适度的因素主要包括气候与环境两方面。以杭州西湖景区为研究对象,尝试将影响舒适度的空气质量、噪音等环境因素与气候因素共同纳入评价体系,选取温度、相对湿度、二氧化碳、一氧化碳、噪音5项指标和6个代表性检测点,进行为期1a定时定点检测,在排除二氧化碳与一氧化碳影响的基础上,构建了旅游环境舒适度评价模型,研究景区尺度存在的旅游环境舒适度时空分异特征。研究发现:不舒适时段主要集中在1月上旬到2月下旬,舒适和较舒适时段主要集中于2月下旬到7月中旬、8月下旬到11月下旬;山区与湖区各项环境指标要优于近城区、游客集聚区及交通繁忙区,平均舒适度山区(1.30)湖心区(1.66)城区(1.82)近城区(2.02)游人集聚区(2.47)交通繁忙区(2.48)。6个观测点在不同时段表现的舒适度差异也不同,差异最大的时段出现在4月中旬到5月中旬,差异最小时段出现在1月上旬到2月下旬。温湿度与噪音存在反向协同作用,引起环境舒适度变化。温湿度舒适时段往往旅游活动频繁,导致噪音升高降低了旅游环境舒适度。温湿度不舒适期旅游活动减少使得声环境相对舒适。  相似文献   
75.
From the Bavarian Early/Middle Miocene (MN5) site Sandelzhausen, nine species of carnivoran mammals are identified including the hemicyonine ursid Hemicyon stehlini, the amphicyonids Amphicyon cf. major and Pseudarctos bavaricus, the mustelids Ischyrictis zibethoides and Martes cf. munki, the mephitid Proputorius pusillus, the viverrid Leptoplesictis cf. aurelianensis, the felid Pseudaelurus romieviensis, and finally the recently described barbourofelid Prosansanosmilus eggeri. With these taxa present, Sandelzhausen shows a carnivoran community typical, though deprived, for the Lower to Middle Miocene of Europe, but different from roughly contemporary Mediterranean faunas such as those from Çandir or Pa?alar in Turkey.  相似文献   
76.
Three genera of lagomorphs, Prolagus, Lagopsis, and “Amphilagus,” were identified during a revision of the lagomorph material from Sandelzhausen (MN5, Early/Middle Miocene boundary, southern Germany). Evidence of two morphological and dimensional classes were observed at some tooth positions in Prolagus (some p3 show an unmistakable P. oeningensis morphology, others closely resemble P. crusafonti), but not at other tooth positions (e.g., M1–2). Insufficient data from Sandelzhausen precludes identification of two different species of Prolagus from this locality, and to define the characteristics of the possible P. crusafonti-like species. Thus, all Prolagus specimens have been classified as P. aff. oeningensis. The genus Lagopsis is represented by L. cf. penai, whose presence is compatible with a MN5 age. The relative abundance of Lagopsis to Prolagus may indicate relatively cool and wet palaeoclimatic conditions. The largest primitive lagomorph species from continental Europe is present at Sandelzhausen. Morphological and dimensional comparisons with other European primitive lagomorphs exclude any affinity with the genera Eurolagus and Titanomys and with the species included in “Amphilagus ulmensis”. Some common features with “Amphilagus antiquus” were observed, although they are not sufficient for the attribution to this taxon. Until there is a general revision of European primitive lagomorphs, the Sandelzhausen giant lagomorph is classified as “Amphilagus” sp. Its origins, whether from evolution within Europe or migration from Asia, remain unknown.   相似文献   
77.
ABSTRACT Emerging methods in habitat and wildlife population modeling promise new horizons in conservation but only if these methods provide robust population-habitat linkages. We used Breeding Bird Survey (BBS) data to verify and validate newly developed habitat suitability index (HSI) models for 40 priority landbird species in the Central Hardwoods and West Gulf Coastal Plain/Ouachitas Bird Conservation Regions. We considered a species’ HSI model verified if there was a significant rank correlation between mean predicted HSI score and mean observed BBS abundance across the 88 ecological subsections within these Bird Conservation Regions. When we included all subsections, correlations verified 37 models. Models for 3 species were unverified. Rank correlations for an additional 5 species were not significant when analyses included only subsections with BBS abundance >0. To validate models, we developed generalized linear models with mean observed BBS abundance as the response variable and mean HSI score and Bird Conservation Region as predictor variables. We considered verified models validated if the overall model was an improvement over an intercept-only null model and the coefficient on the HSI variable in the model was >0. Validation provided a more rigorous assessment of model performance than verification, and models for 12 species that we verified failed validation. Species whose models failed validation were either poorly sampled by BBS protocols or associated with woodland and shrubland habitats embedded within predominantly open landscapes. We validated models for 25 species. Habitat specialists and species reaching their highest densities in predominantly forested landscapes were more likely to have validated models. In their current form, validated models are useful for conservation planning of priority landbirds and offer both insight into limiting factors at ecoregional scales and a framework for monitoring priority landbird populations from readily available national data sets.  相似文献   
78.
Assessment of arbovirus vector infection rates using variable size pooling   总被引:2,自引:0,他引:2  
Pool testing of vector samples for arboviruses is widely used in surveillance programmes. The proportion of infected mosquitoes (Diptera: Culicidae) is often estimated from the minimum infection rate (MIR), based on the assumption of only one infected mosquito per positive pool. This assumption becomes problematic when pool size is large and/or infection rate is high. By relaxing this constraint, maximum likelihood estimation (MLE) is more useful for a wide range of infection levels that may be encountered in the field. We demonstrate the difference between these two estimation approaches using West Nile virus (WNV) surveillance data from vectors collected by gravid traps in Chicago during 2002. MLE of infection rates of Culex mosquitoes was as high as 60 per 1000 at the peak of transmission in August, whereas MIR was less than 30 per 1000. More importantly, we demonstrate roles of various pooling strategies for better estimation of infection rates based on simulation studies with hypothetical mosquito samples of 18 pools. Variable size pooling (with a serial pool sizes of 5, 10, 20, 30, 40 and 50 individuals) performed consistently better than a constant size pooling of 50 individuals. We conclude that variable pool size coupled with MLE is critical for accurate estimates of mosquito infection rates in WNV epidemic seasons.  相似文献   
79.
疏浚后杭州西湖浮游动物群落的变化   总被引:2,自引:1,他引:2  
2003年1-12月调查了疏浚后杭州两湖(小型、浅水、富营养化湖泊)四个采样站(Ⅰ-Ⅳ)浮游动物群落的变化。研究包括优势种组成、密度和生物量,以及浮游动物生物量与水体叶绿素a、有机物耗氧量、总氮和总磷含量之间的相关分析。疏浚后,Ⅲ-Ⅳ站原生动物第一优势种由似铃壳虫(Tintinnopsis sp.)变为筒壳虫(Tintinnidium sp.);Ⅲ-Ⅳ站轮虫第一优势种由暗小异尾轮虫(Trichocerca pusilla)变为针簇多肢轮虫(Polyarthra trigla);Ⅰ站的长额象鼻溞(Bosmina longirostris)和Ⅲ站的微型裸腹溞(Moina micrura)分别取代了长肢秀体溞(Diaphanosoma leuchtenbergianum)第一优势种的地位;桡足类中,剑水蚤优势种为粗壮温剑水蚤(Thermocyclops dybowskii),哲水蚤优势种为汤匙华哲水蚤(Sinocalanus dorrii)。疏浚后,西湖浮游动物平均密度增加了80.5%,其中原生动物密度增量贡献57.3%。平均生物量增加了49.7%,其中轮虫生物量增量贡献36.5%。西湖浮游动物生物量与水体叶绿素a、有机物耗氧量和总磷含量之间均呈垃著的正相关关系。不同采样站中,以Ⅳ站环境生态因子与浮游动物生物量之间的相关程度最高,其次为Ⅲ站、Ⅰ站和Ⅱ站,水体环境生态因子对浮游动物的影响程度与其优势利演变的体现相一致。在不同浮游动物类群中,枝角类生物量与水质生态因子之间的相关程度最高,其次为轮虫、桡足类和原生动物。  相似文献   
80.
This paper explores the temporal stability of growth/climate relationships in ring-width chronologies of Norway spruce [ Picea abies (L.) Karst] and silver fir ( Abies alba Mill) in the Lower Bavarian Forest region in southern Germany. These chronologies were compiled, using both historic and living tree-ring data, with the main aim of developing a dendroclimatic reconstruction for the region covering the last 500 years. Moving window correlation analysis shows that prior to the twentieth century, both species co-vary in a similar way (1480–1899 mean r =0.66). There is no significant correlation between the species chronologies since ca. 1930, which partly reflects anomalous growth trends in the fir chronology since ca. 1960. Multiple regression analysis was utilised to assess the ability of both species chronologies to model March–August precipitation. The precipitation signal of the spruce data was found to be both stronger than the fir data (1872–1930 calibration: r 2=0.45 vs 0.25) and more time stable. After ca. 1930, the fir chronology loses it ability to model March–August precipitation until there is no climate signal at all in the fir data in recent decades. The spruce data also express a later weakening in their climate signal in the mid 1970s. We present compelling evidence indicating that the anomalous trends observed in the fir data, since the mid 1960s, appear to be predominantly related to local SO2 emissions from power plants and refineries. It is also likely that this local anthropogenic forcing is the cause of the weakening of the climate signal in the spruce data since the mid 1970s. The conclusions from this study are: (1) The fir tree-ring data cannot be used for traditional dendroclimatic calibration, although prior to the twentieth century the decadal variability in the fir data is very similar to spruce and so these data could be used to extend potential reconstructions in the future; (2) The recent decline and recovery event in the fir data appears to be unique to the twentieth century and is not part of a natural episodic phenomenon; (3) Traditional dendroclimatic calibration of March–August precipitation will be made using solely the spruce ring-width data. However, due to SO2 forcing in recent decades, the calibration period will be shortened to the 1871–1978 period.  相似文献   
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