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1.
The bat fauna of 35 islands in a large lake in central Sweden were examined using ultrasound detectors. We tested the hypothesis that there is no difference in species number between the mainland and the island fauna. Eight species were found. Species numbers were analysed against island area, area of some habitats (coniferous forest, deciduous forest, semi-open habitats and open habitats), degree of isolation (distance from mainland and from stepping stones) and time spent searching for bats. Species number increased with area of deciduous forest. Presence of houses tended to increase species number. There seems to be a negative relationship between species number and degree of isolation (nearly significant). The results suggest that at least three species, Myotis brandti (Eversmann, 1845), M. mystacinus (Kuhl, 1819) and Plecotus auritus (Linnaeus, 1758), are negatively affected by forest patchiness. These species occurred mainly on large islands. Thus, the results do not support the hypothesis. The reasons why some species avoid open habitats are discussed.  相似文献   
2.
东南亚地处热带,生物多样性极为丰富,可分为4个热点地区:印度-缅甸区的中南半岛、巽他区(含马来半岛、婆罗洲、苏门答腊岛)、菲律宾区(菲律宾群岛)、华莱士区(苏拉威西岛、爪哇岛、马鲁古群岛、小巽他群岛等)。中南半岛在泥盆纪便已是欧亚大陆的一部分,在印度板块撞击欧亚大陆之后受挤压而出;巽他区来自于冈瓦纳古陆和澳洲古陆;菲律宾群岛部分来自于劳亚古陆的碎片向南漂移,部分来自于太平洋西南岛弧的向北迁移;华莱士区则是劳亚古陆碎片、太平洋西南岛弧以及澳洲古陆北侧碎片的组合。巽他区地处赤道,常年温湿;菲律宾区、华莱士区、中南半岛则都受到不同程度的季风气候决定的干湿季变动。地质历史和季风气候影响程度的不同,奠定了东南亚4个生物多样性热点地区的雏形。华莱士区保存有大量的早期被子植物原始类群如睡莲目(Nymphaeales)和木兰藤目(Austrobaileyales),是现代被子植物起源地和冰期避难所之一。巽他区(婆罗洲)和中南半岛是亚洲热带植物的现代分布中心和"进化前沿",是整个东南亚地区重要的种源;而华莱士区的爪哇岛和小巽他群岛主要是物种迁入和中转的种库。这样的物种形成历史与迁移格局,塑造了东南亚4个生物多样性热点地区物种多样性水平与地理范围的基本格局。巽他区和印度-缅甸区曾在冰期通过陆桥相连,使得东南亚成为周边植物扩散交汇的一个"十字路口"。但是,人们对东南亚生物多样性热点地区的物种长距离扩散规律及植物地理学分区仍存在分歧;东南亚与邻近生物多样性热点地区如新几内亚岛、西高止山脉-斯里兰卡、中国横断山区的历史联系,还尚待深入解析。利用现代分子生物学技术,覆盖整个东南亚地区进行全域取样开展代表性类群的物种迁移与生物地理学研究,有望进一步揭示东南亚生物多样性热点地区的形成过程与演化趋势。  相似文献   
3.
舟山海域大中型浮游动物群落时空变化及受控要素   总被引:1,自引:0,他引:1  
为更好地保护舟山海域的渔业资源和生态环境,了解舟山海域浮游动物组成的时空变化,于2014年到2017年对舟山海域33个站位开展4个季节的生态综合调查,结果表明:4个航次共鉴定出浮游动物成体88种和浮游幼体19类,优势种共12种,浮游动物的优势种更替和群落特征季节变化明显,春夏、夏秋、秋冬、冬春相邻季节优势种更替率分别为75%、80%、100%和60%;平均生物量为夏季(176.34 mg/m3)>春季(120.20 mg/m3)和秋季(86.28 mg/m3)>冬季(7.21 mg/m3);平均丰度为夏季(143.97个/m3)>春季(86.30个/m3)>秋季(21.38个/m3)和冬季(26.86个/m3);平均多样性指数:夏季(3.03)>秋季(2.82)>春季(2.05)>冬季(1.71)。舟山海域浮游动物群落具有明显的季节和区域差异,温度、盐度、Chl a和营养盐是影响舟山浮游动物群落时空变化的主要环境因素,其中春季浮游动物群落空间分布主要受盐度的影响,夏季主要受温度、盐度和Chl a的影响,秋季主要受Chl a的影响,冬季主要受悬浮物和溶解氧的影响,而营养盐对每个季节的浮游动物群落分布都有一定的影响。  相似文献   
4.
A male specimen of Bombus terrestris (L. 1758) showing an intermediate colour between the subspecies xanthopus Kriechbaumer 1870 endemic to Corsica and the subspecies terrestris ubiquitous in the mainland was found within samples collected in 1999 on the Tuscan coast. Hybrid specimens between these subspecies are common on some of the islands of the Tuscan archipelago, while others only have pure populations. The finding is significant as it could signal the spread of the subspecies xanthopus_to the mainland. We consider and discuss the circumstances of the finding.  相似文献   
5.
The Burseraceae are a medium‐sized family in which 18 genera are currently recognised. They are the subject of a long‐term project to describe the pollen morphology from light, scanning electron and transmission electron microscopy. The pollen morphology of tribe Protieae has been published, as well as an account of the pollen of the African taxa in the family. Pollen data for the other two tribes, Bursereae and Canarieae, are more or less complete. The pollen of all the genera have been examined, with the exception of the recently described Pseudodacryodes Pierlot for which, currently, there is no pollen material available. This paper summarises the results.

There is considerable variation in exine and aperture features between, and occasionally within, the genera and 14 major pollen types are defined, including two previously undescribed types: ‘Canarium oleiferum’ and ‘Canarium gracile’. The distribution of pollen characteristics throughout the family is compared with previously published tribal and subtribal groupings, as well as with current ideas of generic relationships from molecular analyses. Comparisons show notable congruence of pollen data with molecular data. To some extent pollen morphology is different for each of the subtribes. Nevertheless, there are some notable exceptions, for example, the pollen of Garuga and Boswellia are remarkably similar, although Garuga has been included, somewhat tenuously, in tribe Protieae, and Boswellia is included in tribe Bursereae, subtribe Boswelliinae. In a recent molecular tree Garuga and Boswellia appear to be closely related, and this supports the conclusion, based on several macromorphological characters as well as pollen, that Garuga should be transferred to tribe Bursereae.  相似文献   
6.
Background: The South Aegean Volcanic Arc (SAVA), one of the most notable geological structures of the Mediterranean Sea, is floristically well known. Nevertheless, the factors that contribute to shaping the plant species richness of the SAVA remain unclear.

Aims: To investigate the factors that affect plant species richness and identify plant diversity hotspots in the SAVA and other central Aegean islands.

Methods: We used stepwise multiple regression to test the relationship between a number of environmental factors and plant species richness in the SAVA, as well as the residuals from the species–area linear regressions of native, Greek and Cycladian endemic taxa as indicators of relative species richness.

Results: The area was confirmed to be the most powerful single explanatory variable of island species richness, while geodiversity, maximum elevation and mean annual precipitation explained a large proportion of variance for almost all the species richness measures. Anafi, Amorgos and Folegandros were found to be endemic plant diversity hotspots.

Conclusions: We have demonstrated that geodiversity is an important factor in shaping plant species diversity in the Cyclades, while mean annual precipitation, human population density and maximum elevation were significant predictors of the Greek endemics present in the Cyclades. Finally, Anafi was found to be a plant diversity hotspot in the South Aegean Sea.  相似文献   
7.
8.
When males fight for access to females, such conflict rarely escalates into lethal fight because the risks and costs involved, that is, severe injury or death, are too high. The social spider mite, Stigmaeopsis miscanthi, does exhibit lethal male fights, and this male–male aggressiveness varies among populations. To understand the evolution of lethal fighting, we investigated aggressiveness in 42 populations and phylogenetic relationships in 47 populations along the Japanese archipelago. By analysis of the male weapon morph, a proxy for aggressiveness, we confirmed the existence of a mildly aggressive (ML) form, besides the low aggression (LW) and high aggression (HG) forms reported earlier. To evaluate demographic history of these three forms, we employed the approximate Bayesian computation approach using mtCOI sequences and taking into consideration the postlast glacial expansion history of the host plant, Miscanthus sinensis. As results, hierarchical split models are more likely to explain the observed genetic pattern than admixture models, and the ML form in the subtropical region was considered the ancestral group. The inferred demographic history was consistent with the one reconstructed for the host plant in a previous study. The LW form was split from the ML form during the last glacial period (20,000–40,000 years BP), and subsequently, the HG form was split from the ML form at the end of or after the last glacial period (5,494–10,988 years BP). The results also suggest that the mite invaded Japan more than once, resulting in the present parapatric distribution of LW and HG forms in eastern Japan.  相似文献   
9.
The adaptive radiation of flowering plants as manifested by the floral diversity has long been considered associated with the diversity of plant–pollinator interactions, because changes in plant–pollinator interactions are hypothesized as one of the major mechanisms driving plant ecological speciation. To understand the relative contributions of various mechanisms for plant radiation, including pollinator changes, it is useful to study a plant group for which comparative study of the species life history across the whole lineage is feasible. To this end, we will focus on the plant lineages that have presumably radiated in the Japanese archipelago, namely, the genera Asimitellaria, Asarum, and Arisaema. By comparing these three genera, we will comment on the possible modes of adaptive radiation and diversification among the endemic flora of Japan.  相似文献   
10.
用Shannon-Wiever多样性指数、Pielous种类均匀度、Margalef种类丰度、McNaushton优势度4个测定群落种类多样性指标进行数值分析.结果表明,嵊泗列岛从近岸到外海.H’(S)、J、d值呈现逐渐增加的趋势.而D值则有逐渐减小的趋势;各断面多样性指数H’(S)以春、秋季较高,J值则基本上以春、冬季稍高,d值则随断面的不同有差异,D值基本上以夏、秋季为高用Whiftaker和Fairbanks群落系数计算公式及Bray-Curtis群落相似性指数进行群落相似性及聚类分析,结果表明,嵊泗列岛潮间带底栖动物群落结构可聚为两大类型,从结构上看.近外海底栖动物群落为近岸及外海群落的过渡类型.  相似文献   
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