Radiocarbon evidence of mid-Holocene mammoths stranded on an Alaskan Bering Sea island

Island colonization and subsequent dwarfing of Pleistocene proboscideans is one of the more dramatic evolutionary and ecological occurrences, especially in situations where island populations survived end-Pleistocene extinctions whereas those on the nearby mainland did not. For example, Holocene mammoths have been dated from Wrangel Island in northern Russia. In most of these cases, few details are available about the dynamics of how island colonization and extinction occurred. As part of a large radiocarbon dating project of Alaskan mammoth fossils, I addressed this question by including mammoth specimens from Bering Sea islands known to have formed during the end-Pleistocene sea transgression. One date of 7,908 +/- 100 yr bp (radiocarbon years before present) established the presence of Holocene mammoths on St Paul Island, a first Holocene island record for the Americas. Four lines of evidence--265 accelerator mass spectrometer (AMS) radiocarbon dates from Alaskan mainland mammoths, 13 new dates from Alaskan island mammoths, recent reconstructions of bathymetric plots and sea transgression rates from the Bering Sea--made it possible to reconstruct how mammoths became stranded in the Pribilofs and why this apparently did not happen on other Alaskan Bering Sea islands.     

Bone histology indicates insular dwarfism in a new Late Jurassic sauropod dinosaur

Sauropod dinosaurs were the largest animals ever to inhabit the land, with truly gigantic forms in at least three lineages. Small species with an adult body mass less than five tonnes are very rare, and small sauropod bones generally represent juveniles. Here we describe a new diminutive species of basal macronarian sauropod, Europasaurus holgeri gen. et sp. nov., and on the basis of bone histology we show it to have been a dwarf species. The fossils, including excellent skull material, come from Kimmeridgian marine beds of northern Germany, and record more than 11 individuals of sauropods 1.7 to 6.2 m in total body length. Morphological overlap between partial skeletons and isolated bones links all material to the same new taxon. Cortical histology of femora and tibiae indicates that size differences within the specimens are due to different ontogenetic stages, from juveniles to fully grown individuals. The little dinosaurs must have lived on one of the large islands around the Lower Saxony basin. Comparison with the long-bone histology of large-bodied sauropods suggests that the island dwarf species evolved through a decrease in growth rate from its larger ancestor.     

Genetic fingerprinting reflects population differentiation in the California Channel Island fox

Restriction fragment profiles generated by hybridization of hypervariable minisatellite DNA probes have been used for paternity analysis but not for comparisons at the level of populations, because the profiles are thought to evolve too rapidly to be informative over large time intervals. But in small isolated populations, the fixation of restriction-fragment polymorphisms can outpace the generation of fragment-length variability through recombination. Here we report on an analysis of DNA fingerprints of the California Channel Island fox (Urocyon littoralis). These foxes comprise an island dwarf species found only on six of the Channel Islands off the coast of southern California. Variability of restriction-fragment profiles within fox populations, as indicated by the average percentage difference (APD), varied widely among the islands, from 0.0% (no variation) to 25.3%. The APDs between populations were considerably greater (43.8% to 84.4%). In addition, foxes on each island can be distinguished by the presence of diagnostic restriction fragments. Maximum parsimony and phenetic trees relating foxes from different islands are consistent with the archaeozoological and geological record. Therefore, in small populations of genetically isolated mammals, differences among hypervariable restriction-fragment profiles can be used to estimate relative genetic variability and to reconstruct the evolutionary relationships of natural populations.     

辽宁海岛分布特征与形状功能分析

辽宁海岛主要分布在北黄海海域，属于小岛、近陆岛和无人岛为主的海岛省．本文在阐明海岛分布特征的基础上，着重计算了辽宁省有人岛的形状率并分析其形状功能     

A land-bridge island perspective on mammalian extinctions in western North American parks

In recent years, a number of authors have suggested several geometric principles for the design of nature reserves based upon the hypothesis that nature reserves are analogous to land-bridge islands. Land-bridge islands are islands that were formerly connected to the mainland and were created by a rise in the level of the ocean. Land-bridge islands are considered supersaturated with species in that the ratio of island to mainland species numbers is higher than expected from the area of the island. As a result, the rate of extinction should exceed the rate of colonization on a land-bridge island, resulting in a loss of species that is suggested to be related to the size and degree of isolation of the island. If nature reserves are considered to be similar to land-bridge islands, because most are slowly becoming isolated from their surroundings by habitat disturbance outside the reserves, several predictions follow. First, the total number of extinctions should exceed the total number of colonizations within a reverse; second, the number of extinctions should be inversely related to reserve size; and third, the number of extinctions should be directly related to reserve age. I report here that the natural post-establishment loss of mammalian species in 14 western North American national parks is consistent with these predictions of the land-bridge island hypothesis and that all but the largest western North American national parks are too small to retain an intact mammalian fauna.     

Predicted methylation landscape of all CpG islands on the human genome

CpG island methylation plays important role in various biological processes. To investigate methylation landscape of all CpG islands on the human genome, we develop a model for predicting the CpG island methylation status. This model outperforms other existing methods. We apply the model on the whole human genome and predict the landscape of DNA methylation of all CpG islands. Based on the methylation profile, we find that about 31% of CpG islands are methylation-prone and CpG islands located in promoter regions are seldom methylated. There is no significant difference in the CpG island methylation level between R and G bands among the chromosomes. The occupancy of RNA polymerase II is significantly higher in methylation-resistant promoter CpG islands, indicating that genes with such promoter CpG islands tend to be more active.     

水下隧道中人工岛建设现状及主要问题

针对跨海水下隧道工程中人工岛建设的研究现状及主要问题，收集了典型的跨海水下隧道人工岛的工程实例，总结了跨海水下隧道人工岛的地基处理、围堰构建和填土加固的关键施工技术，指出软弱地基处理及填土加固方案组合和工序优化以及疏浚土在国内人工岛建设中利用较少是跨海水下隧道人工岛建设过程中两大主要问题；基于现有的人工岛建设技术，人工岛建设的未来发展方向是通过预制人工岛构件实现绿色快速筑岛。     

人工岛群对弱潮区海岸动力影响的叠加效应分析

为科学评价人工岛群对周边海岸动力产生的影响,基于MIKE21数值模拟软件建立秦皇岛金梦海湾潮流模型和波浪模型,运用验证合理的模型计算人工岛(群)作用下的潮流场和波浪场。在对金梦海湾已建人工岛群影响下的区域动力过程特征分析的基础上,选取合适分析点研究人工岛间的相互作用。研究表明,由于莲花岛与海螺岛的阻流、导流和分流作用,潮流在海螺岛与岸线之间形成较大范围弱环流区,流速几乎为零,并在莲花岛与海螺岛形成的口门处及人工岛群外侧海域形成流速显著增加区域。这3处区域流场受人工岛群影响最大,其中海螺岛起到控制性作用。在人工岛群共同作用下金梦海湾潮流的变化不是各单一人工岛作用下变化的线性叠加,而有效波高受人工岛间相互作用的影响是线性的。人工岛群对金梦海湾起到很好的消浪效果,但却大大削弱了近岸区域的潮流动力。     

俄日北方四岛纠纷及其对东北亚局势的影响

北方四岛在历史上曾多次易主。二战期间,苏联根据《波茨坦公告》重新占领了北方四岛,并将其划为自己的版图。2010年11月,俄罗斯总统梅德韦杰夫视察了国后岛,引发新一轮俄日岛屿纠纷。从目前形势来看,俄罗斯在岛屿争端中占据有利的位置,不会将北方四岛交还日本。俄日岛屿纠纷的彻底解决,还有很长的一段路要走。俄日岛屿争端将影响大国关系的调整,加剧东北亚紧张局势,导致地区内国际力量对比与战略格局的重新组合。     

Analysis of an evolutionary species-area relationship

Large islands typically have more species than comparable smaller islands. Ecological theories, the most influential being the equilibrium theory of island biogeography, explain the species-area relationship as the outcome of the effect of area on immigration and extinction rates. However, these theories do not apply to taxa on land masses, including continents and large islands, that generate most of their species in situ. In this case, species-area relationships should be driven by higher speciation rates in larger areas, a theory that has never been quantitatively tested. Here we show that Anolis lizards on Caribbean islands meet several expectations of the evolutionary theory. Within-island speciation exceeds immigration as a source of new species on all islands larger than 3,000 km2, whereas speciation is rare on smaller islands. Above this threshold island size, the rate of species proliferation increases with island area, a process that results principally from the positive effects of area on speciation rate. Also as expected, the slope of the species-area relationship jumps sharply above the threshold. Although Anolis lizards have been present on large Caribbean islands for over 30 million years, there are indications that the current number of species still falls below the speciation-extinction equilibrium.     

Sympatric speciation in palms on an oceanic island

The origin of species diversity has challenged biologists for over two centuries. Allopatric speciation, the divergence of species resulting from geographical isolation, is well documented. However, sympatric speciation, divergence without geographical isolation, is highly controversial. Claims of sympatric speciation must demonstrate species sympatry, sister relationships, reproductive isolation, and that an earlier allopatric phase is highly unlikely. Here we provide clear support for sympatric speciation in a case study of two species of palm (Arecaceae) on an oceanic island. A large dated phylogenetic tree shows that the two species of Howea, endemic to the remote Lord Howe Island, are sister taxa and diverged from each other well after the island was formed 6.9 million years ago. During fieldwork, we found a substantial disjunction in flowering time that is correlated with soil preference. In addition, a genome scan indicates that few genetic loci are more divergent between the two species than expected under neutrality, a finding consistent with models of sympatric speciation involving disruptive/divergent selection. This case study of sympatric speciation in plants provides an opportunity for refining theoretical models on the origin of species, and new impetus for exploring putative plant and animal examples on oceanic islands.     

三种药剂对紫罗兰的矮化效应

应用PP333、矮丰和水杨酸对紫罗兰进行叶面喷施处理,研究其对株高、花期、叶片长宽比、叶绿素含量的影响.结果表明:经PP333处理的紫罗兰株型明显矮化,经水杨酸处理的紫罗兰花期显著延长,初花期提前,但矮化效果不显著.综合效果看,叶面喷施质量浓度为0.2 mg/L的PP333对紫罗兰的作用效果较好(株高极显著矮化且未发生莲座化现象).叶面喷施水杨酸对提高紫罗兰叶绿素含量的影响最大.     

科学技术视角下岛屿问题分析

结合科学技术与法律之间的关系,分析了如何从科学技术角度理解《海洋法公约》关于岛屿制度的规定。指出有效控制原则是国际法院解决岛屿争议的主要原则,而科学技术是实现对岛屿有效控制的重要手段。法律可以规范科学技术对岛屿问题产生的负面影响。     

Pt／Pt（111）薄膜生长的计算机模拟研究

以Pt/Pt(111)薄膜生长为例,建立一个包含更为细致的原子扩散过程的模型,采用蒙特卡洛模拟方法研究了不同覆盖率,不同温度下（111）面上外延生长早期阶段的原子聚集行为,得到了一系列分形状薄膜的形貌。计算表明,用来描述枝状晶体枝杆平均宽度的原子的平均最近邻配位数随温度的升高而增加,与扫描隧道电镜实验测量的结果一致。同时,还研究了原子沉积过程中沉积速率的大小对薄膜生长的影响。     

Ocean currents mediate evolution in island lizards

Islands are considered to be natural laboratories in which to examine evolution because of the implicit assumption that limited gene flow allows tests of evolutionary processes in isolated replicates. Here we show that this well-accepted idea requires re-examination. Island inundation during hurricanes can have devastating effects on lizard populations in the Bahamas. After severe storms, islands may be recolonized by over-water dispersal of lizards from neighbouring islands. High levels of gene flow may homogenize genes responsible for divergence, and are widely viewed as a constraining force on evolution. Ultimately, the magnitude of gene flow determines the extent to which populations diverge from one another, and whether or not they eventually form new species. We show that patterns of gene flow among island populations of Anolis lizards are best explained by prevailing ocean currents, and that over-water dispersal has evolutionary consequences. Across islands, divergence in fitness-related morphology decreases with increasing gene flow. Results suggest that over-water dispersal after hurricanes constrains adaptive diversification in Anolis lizards, and that it may have an important but previously undocumented role in this classical example of adaptive radiation.     

Innovation for ascertaining genomic islands in PAO1 and PA14 of Pseudomonas aeruginosa

Based on three distinct traits of genomic islands, a novel approach was developed to search for and determine genomic islands in special strains. Two genomic islands in Pseudomonas aeruginosa PAO1 and 7 genomic islands in Pseudomonas aeruginosa PA14 were defined with this method. Among the 9 genomic islands, 4 islands had been characterized before, while the other 5 islands were initially determined. The insert sites of 6 genomic islands are tRNA sequences, direct repeats of PA14GI-3 are relative to tRNA^Leu, and direct repeats of PA14GI-2 are at the 3＇ end of bifunctional GMP synthase/ glutamine amidotransferase. Only direct repeats of PA14GI-4 are not clear. Among the 5 newly-found genomic islands, it was supposed that PA14GI-2 is a genomic island related to Hg^2＋ uptake, PA14GI-3 is a secretory activity genomic island, PA14GI-6 is a pathogenicity island, and functions of PA14GI-1 and PA14GI-5 are not clear. Finally, the tyrosine type integrases in PAOIGI-1, PA14GI-5 and PA14GI-7 were analyzed, and their binding and restriction sites were predicted.     

基于知识网络的高校数字教学资源平台的共建与共享

现今很多高校都遇到了一个非常棘手的问题：校园内的“资源孤岛”造成众多“信息孤岛”的存在。而“信息孤岛”使得高校信息数据的一致性无法保证、信息无法共享和利用。因此，建立一个基于知识网络的高校数字教学资源的共建、共享平台，可以保存各种珍贵的信息资源，为用户提供丰富的素材和知识资源，通过资源的链接和信息共享，达到更高层次的互动。     

明清时期闽台海岛状况蠡测

明清时期,闽台海岛开发经历了巡检司、卫所或寨游、军镇发展为海岛行政区.海岛居民的经济开拓,减轻了海禁政策的消极影响,由传统自然经济向以海洋经济为导向的商品经济过渡,海岛的经济发展与军事驻防相辅相成.海岛教育基本上按照内地的模式,共同的科举制度将海岛与内地的读书人紧密地联系在一起,思想文化上相互影响,形成了有鲜明的区域特色的闽台文化.探讨海岛开发的不利因素与不足之处,祈望能为发展海洋经济提供有益的借鉴.     

基于多源卫星资料的太原市城市热岛效应分析

“十五”以来,太原市建成区面积不断扩大,人口数量不断增加,人为活动以及下垫面的变化会影响太原市地表温度的时空分布,城市热岛现象也随之发生变化。为了对太原市今后城市发展及生态文明建设提供科学依据,利用Aqua/MODIS、数字高程、土地利用分类、城市灯光等多源卫星资料计算太原市2003～2019年城市热岛强度和城市热岛比例指数,分析太原市城市热岛效应时空变化特征,并结合高空间分辨率的Landsat8数据分析太原市热岛区和冷岛区下垫面特征。结果表明：2003～2019年,太原市辖区各县（市、区）城市热岛效应较强的月份主要发生在7月～9月,且多在8月城市热岛效应最强,辖区各县（市、区）中小店区城市热岛效应最强;近20年来,太原市辖区各县（市、区）城市热岛强度变化趋势不同,南部的小店区、晋源区和清徐县城市热岛强度整体增加趋势明显且逐渐相连成片,在今后城市发展中应重点关注,北部、东北部和西南部郊区的强冷岛区域的面积增加显著,有效缓解了所在县（市、区）的热岛强度;在城市发展建设中,注意金属、混凝土或塑胶等建筑吸热材料对局部热岛效应的加强作用,可通过大面积水体、植被等缓解局部地区热岛效应。     

Single origin of a pan-Pacific bird group and upstream colonization of Australasia

Oceanic islands have long served as natural laboratories for understanding the diversification of life. In particular, the many thousands of islands spanning the tropical Pacific support an unparalleled array of terrestrial communities whose patterns of diversity contributed fundamental insights to the development of classical speciation and biogeographic theory. Much of this work is founded on an assumption derived from traditional taxonomic approaches, namely that faunas on these widely separated archipelagos stem from a simple one-way, downstream flow of colonists from continents to islands. Here we show, with the use of molecular phylogenetic data from one of the original bird families used to justify this assumption, that a diverse array of endemic island genera and species are the product of a single radiation that diversified across all major Pacific archipelagos in a non-stepping-stone fashion, and recently recolonized continental areas. The geographic scope and lineage-specific approach of this study reveal evolutionary patterns long obscured by traditional taxonomic surveys and indicate that widely dispersed archipelagos can be sources of biological diversity.