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31.
32.
Everett H. Lindsay 《Geobios》1977,10(4):597-623
Simimys is a late Eocene and earliest Oligocene genus that shares dipodoid (zygoma) and muroid (dental) characters. The Oligocene record of dipodoid rodents includes Plesiosminthus from middle Oligocene deposits of Asia and late Oligocene deposits of Europe. The Oligocene record of muroid rodents includes at least two genera (Eucricetodon and (Cricetops)) from Asia, six genera (Eucricetodon, Pseudocricetodon, Melissiodon, Paracricetodon, Heterocricetodon and Adelomyorion)) from Europe, and three genera (Eumys, Scottimus and Nonomys)) from North America. The known record, as given above, suggests that Siminys is the earliest and most primitive genus with muroid affinities; it also implies that muroid rodents were derived from unknown Eocene dipodoid rodents.The Oligocene cricetid rodents display progressive expansion and inclination of the anterior plate of the zygoma. These changes in the zygoma probably reflect evolutionary stages in the development of a myomorphous zygoma from an hystricomorphous zygoma. Changes in the zygoma apparently took place at different rates and times in Asia. Europe, and North America; they probably reflect differenciation of Cricetodontinae in Palaearctica, and Eumyinae in Nearctica during the Oligocene.  相似文献   
33.
A system of nature reserves is a necessary component of an integrated conservation strategy. The basic problem in the design of a nature reserve system is to select the smallest number of sites from a region for some conservation objectives. There are 33 nature reserves intended for the conservation of Red-Crowned Crane (Grus japonensis), totalling 3.1 million ha. Other habitats of Red-Crowned Crane are facing severe problems due to economic development and other human activities. GIS, iterative methods and the integer programming approach were employed to design the nature reserve system for Red-Crowned Crane, with conservation goals to protect 70 and 60% areas of highly and moderately suitable wetlands, respectively. The results indicated the need to designate six new nature reserves in Wulagai marsh, Duluhe River, Tumen River, Rizhao, Gaoyou Lake and Hongze Lake, and showed a protection zone in Songnen Plain (between Heilongjiang Province and Jilin Province) and three clusters of nature reserves in Sanjing Plain, which, will be used as reference for the designation of new nature reserves, or enlargement and adjustment of existing nature reserves. The iterative method and integer programming approaches were feasible for design of nature reserve system.  相似文献   
34.
In the more than twenty years in which long-term canopy research has been conducted, mycology has been largely disregarded. Our studies using a construction crane to gain access to the canopy of a forest in Leipzig, Germany are the first long term investigations assessing the diversity and ecology of wood-decaying fungi in a canopy. Thirty-seven individuals of nine different tree species with a large amount of dead wood were selected. Sampling focussed on the four most prominent tree species Acer pseudoplatanus, Fraxinus excelsior, Quercus robur and Tilia cordata. In the years 2002 and 2003 dead wood was collected in different canopy strata. Dead branches were removed and stored for two weeks in open boxes with high humidity to allow growth of fructifications in the laboratory. 118 different taxa were identified (108 species, 77 genera). Corticioid fungi (e.g., of Corticiaceae, Stereaceae, Hymenochaetaceae) dominated the fungal composition with 37 species, pyrenomycetes were present with 18 species. Agaric fungi (Agaricales and Cortinariales) were scarce. Species with minute basidiomes dominated the fungal composition of this systematic group. Agarics with larger sporomes were found only once and were restricted to strongly decayed branches in shaded canopy areas. Concerning species richness and fungal composition the four tree species mentioned above differed remarkably. As expected, many fungi that grew on bark or slightly decayed wood showed a distinct host and substratum specifity. It is noteworthy that fungi which are purportedly to be non-specific were found on single tree species only.  相似文献   
35.
I report an instance of usurpation of a Crowned Lapwing Vanellus coronatus nest by a pair of African Wattled Lapwings Vanellus senegalensis. The nest, which originally contained a single Crowned Lapwing egg, eventually contained an additional three Wattled Lapwing eggs, before it was predated. Although parents of both species were observed in the vicinity of the nest, video monitoring showed that the Wattled Lapwings incubated all four eggs. Detection of embryonic heart rate suggested that all the eggs were probably viable up until the nest was destroyed. Nest usurpation in shorebirds is rare, and given the easily accommodated nest requirements and minimal costs of nest construction in these species, is difficult to explain. I speculate that the occurrence described here may represent a case of mistaken identity by the female Wattled Lapwing when choosing a nest scrape, since there seems to have been little benefit to the usurping species of taking over an already occupied nest.  相似文献   
36.
鄱阳湖区灰鹤越冬种群数量与分布动态及其影响因素   总被引:1,自引:0,他引:1  
1998—2011年,采用地面同步调查法开展了鄱阳湖越冬灰鹤种群监测,并整合1984—2011年鄱阳湖国家级自然保护区历年的越冬灰鹤最大种群数量,分析了鄱阳湖灰鹤越冬种群动态以及影响其数量变化与空间分布的环境因素。结果表明,近13年来鄱阳湖区越冬灰鹤种群平均数量为(2 335±651)只,种群数量呈增长趋势,2011年冬季记录到最大种群数量7 640只。灰鹤越冬种群数量与10月平均最低气温以及10月平均气温存在显著正相关,与10月平均最大风速存在显著负相关,与各月的平均水位没有显著的相关性。每年冬季灰鹤在鄱阳湖呈聚集型分布。大湖池、大莲子湖、三湖、汉池湖、企湖、珠湖、南湖(共青)、大汊湖等8个湖泊是灰鹤的重点活动区,(74.9±5.6)%的越冬灰鹤分布在保护区之外。灰鹤的空间分布与滩地面积存在显著的正相关,与农田面积、人口密度、村庄数量、8月份初级生产力、11月份初级生产力等环境因子存在显著负相关。滩地面积是影响灰鹤空间分布的重要因子,对灰鹤利用频次空间变化的解释率为15.0%,与11月份初级生产力共同解释了灰鹤年平均群体数量空间变化的24.6%。如竞争、小生境结构、干扰等局地尺度的环境要素对灰鹤空间分布的影响研究将有助于更全面地认识鄱阳湖越冬灰鹤种群动态的影响机制。  相似文献   
37.
云南纳帕海越冬黑颈鹤日间行为模式与年龄和集群的关系   总被引:3,自引:0,他引:3  
2006年10月—2007年5月,在云南省西北部纳帕海,采用路线调查结合瞬时扫描行为取样法,对越冬黑颈鹤(Grus nigricollis)种群的时间分配及其与年龄、集群和时间的关系进行了观察。结果说明,黑颈鹤越冬活动主要是以觅食为主,占日间时间的(76.81±9.1)%。越冬期间黑颈鹤日间行为的节律性较为明显,具有适应高寒气候的特点。集群形式对成鹤的行为有着显著影响,集群和家庭中活动的成鹤在觅食、警戒和争斗中存在显著差异(F1,76= 0.27、0.77, U= 279, P= 0.001—0.000)。年龄是影响鹤群行为的因素之一。幼鹤相比成鹤有较多的觅食时间和休息时间,警戒行为比例较低(F1,76= 0.04—2.59, U= 188—299, P= 0.006—0.000),且不受集群形式的影响。随着越冬期间的早、中、晚3个时期的环境变化,黑颈鹤的时间分配有显著变化(F2,36= 4.63—26.54, 22= 5.29—13.68, P= 0.0016—0.000)。不同越冬地的黑颈鹤行为存在差异。气候、食物资源和人为影响可能是造成这些差异的主要因素。  相似文献   
38.
扁杆藨草(Scirpus planiculmis)和三江藨草(S.nipponicus)的球茎是迁徙白鹤(Grus leucogeranus)在莫莫格中途停歇地的主要食物。2010年9月15~25日,对莫莫格白鹤集中停歇地鹅头泡湿地的20条样线上100 m等间隔470个取样点进行了地下0~20 cm的藨草球茎的取样工作。基于此,采用反距离权重、4种径向基函数和普通克里格共6种空间插值方法模拟了该区域藨草球茎密度。交叉验证和插值结果的空间分布图对比,径向基函数中的张力样条插值效果最佳,是最适于该区域挺水植物藨草球茎密度的空间插值方法。张力样条插值结果表明:研究区内藨草球茎密度均值为(46.0±44.3)个/m2。其中,<25个/m2的面积占研究区的41.7%,25~100个/m2的面积占45.9%,而>100个/m2的面积仅占12.4%。研究结果为下一步分析白鹤迁徙种群与环境因子的生态关系、预测该地区白鹤的环境容纳量提供十分重要的基础数据。  相似文献   
39.
C. BUDDE 《Bioacoustics.》2013,22(2-3):161-173
ABSTRACT

The study describes the vocal repertoire of the Grey Crowned Crane Balearica regulorum gibbericeps and speculates on the purpose the calls serve. The repertoire consists of 4 tonal and 7 non-harmonic calls. Chicks have 3 different vocalizations.  相似文献   
40.
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