中国古代人群头骨的若干赤道人种特征检测

为探讨中国大陆古代人群与赤道人种人群之间的基因交流情况,本项研究对赤道人种的若干特征在中国古代人群头骨中的出现情况作检测。检测的材料包括3800~1200年前生活在新疆、青海、宁夏和河南安阳的12组人群的头骨以及现代华北和云南的人类头骨。结果表明:1)赤道人种若干特征能够在我国古代多个地区的人群中和现代华北和云南人群中检测到,表明中国大陆至少在3000~2000年前已存在赤道人种基因流入蒙古人种的人群之中的现象;2)赤道人种特征平均出现率在中国古代人群中很可能在地理上大致是由东向西递降,与当时这些人群中的欧亚人种特征平均出现率的地理上分布趋势呈相反方向,提示了在中国大陆至少在距今3000-2000年期间已经存在两个相反流向的外来"基因流"。     

华北和云南现代人类头骨的欧亚人种特征

以往的研究表明,在3000-2000年前,"西方基因"已经在我国多个地区存在,这些"西方基因"是经由新疆流向内地的。为探讨这些"西方基因"在中国现代人群中的存在情况,本文对现代华北和云南人类头骨上的欧亚人种特征表现状况作了检查和比较。结果表明:1)欧亚人种特征在现代华北头骨标本和云南头骨标本中都能够检测到。这提示了"西方基因"不仅曾经流向华北,也流向中国西南地区的云南;2)华北头骨所代表的这一人群,在欧亚人种特征平均出现率(AFOERC)上并不比大约3000年前的殷墟人群高。这很可能是由于该华北人群与带有"西方基因"的外界人群往来有限,因而并无更多的"西方基因"流入的缘故;3)云南头骨标本比华北头骨标本在AFOERC上低得多;这可能是该云南人群与当地其他人群发生过频繁的基因交流而弱化了其原有的AFOERC的缘故。     

新疆且末县加瓦艾日克墓地人骨研究

本文通过对新疆且末县托乎拉克勒克乡加瓦艾日克村29座墓地出土的人骨标本进行了观察和分析。共鉴定出150例个体,其中男性73例、女性50例、性别不明者27例。男性、女性平均死亡年龄分别为36.3岁和35.6岁。形态学的分析指出且末人群更多地具有欧洲人种的特点,如鼻根凹陷深、鼻骨明显突起及犬齿窝深等。聚类分析结果显示且末人群与新疆古代人群焉布拉克C组、察吾呼四号组、多岗等人群较为接近。文章还根据线粒体DNA的分析结果讨论了且末古代人群的种族属性,古DNA的分析揭示出且末人群存在欧亚大陆东、西部人群的基因交流,并进一步指出其西部类型的成分来源极有可能来自西伯利亚,其东部成分可能来自西伯利亚或中国甘肃,只是东西方人群的基因融合规模小而且处于初级阶段,所以并未在颅面部形态特征上有大规模明显的改变。此外,本文从考古学文化、体质人类学研究以及古DNA等几个方面探讨了新疆地区古代人群的种族成分来源。本文还对且末人群的身高进行了推算,对一例变形颅骨以及骨骼上的创伤作了简要描述。     

基于线粒体控制区的序列变异分析青海东部甘肃鼢鼠遗传多样性

甘肃鼢鼠(Myospalax cansus)是一种终年营地下独居生活的小型掘土类动物。本文通过测定mt DNA的控制区部分序列(530 bp)变异,分析青海东部地区8个甘肃鼢鼠地理种群遗传多样性与遗传结构。158个样本共发现26个变异位点,定义了39种单倍型,整体的平均单倍型多样性高(h=0.953 2)、核苷酸多样性低(π=0.006 36)。歧点分布和中性检验均说明青海东部甘肃鼢鼠种群在历史上存在着快速扩张的事件。基于邻接法构建的网络关系图中,单倍型呈星状分布,没有按地理位置形成对应类群。基因流(Nm)数据显示多数地理种群间基因交流贫乏,AMOVA结果显示种群内与种群间遗传变异分别为48.82%和51.18%,遗传分化明显。IBD分析表明,甘肃鼢鼠的遗传分化与地理距离呈正相关,说明距离隔离对甘肃鼢鼠种群分化具有重要作用。甘肃鼢鼠的这种遗传多样性与种群遗传结构特点,可能是地下生活方式靠挖掘迁移带来的较小扩散能力的结果。     

新疆于田流水墓地青铜时代人类牙齿非测量性状

我国新疆地区自古以来即是东西方文明相互交融的摇篮,以往的考古学、体质人类学研究表明,该区域内不同文化之间的互通有无早在我国青铜-早期铁器时代便已经发生。关于这种交流与融合产生的原因,目前学术界仍未有定论。新疆于田流水墓地(2950±50 BP)是由中国社会科学院考古研究所于2003-2005年主持发掘的青铜时代墓葬群,该墓地共发掘墓葬65座,被视为是昆仑山北麓发现的最早人类文化遗存。本文从采集自流水墓地108例人骨标本的19项牙齿非测量性状研究入手,将其与欧亚大陆范围内的古今人群进行比较研究,并进行史密斯生物学距离的计算以及主成分分析。结果表明:生活在新疆流水地区的古代人类与南西伯利亚地区、日本绳纹、阿富汗/巴基斯坦、中国姜家梁地区人群之间在牙齿非测量性状方面存在某种程度上的相似性,这或许可以说明至少在3000年前,我国新疆西南部地区可能已经存在了东西方的人群迁徙。     

新疆黑尾地鸦初步调查

黑尾地鸦(Podoces hendersoni)属于中亚特有物种,留鸟,栖息于荒漠地区。主要分布于中国的西部,在邻国蒙古和哈萨克斯坦仅有少量分布。国内的分布区主要在新疆、内蒙古、青海、甘肃、宁夏等西部省区。国内关于这个种的研究文献比较缺乏,作者于2001~2005年间进行了野外调查。在准     

中国懒螽属二新种(直翅目:螽斯科)

懒螽属(Zichya Bolivar,1901)的种类主要生活于荒漠、戈壁地区。已知的种类分布于蒙古、苏联、中国的青海和宁夏等地区。1982年在甘肃调查过程中,采到二种懒螽,经鉴定,认为是二新种,现记述如下。 模式标本保存于陕西师范大学生物系。     

中国西北干旱地区农牧业生态系统碳排放的空间分布与演变趋势

研究西北干旱地区农牧业生态系统碳排放的空间分布特点与演变趋势对于我国制定更具针对性的农牧业减排政策具有重要的指导意义。对2000—2013年中国西北干旱地区农牧业生态系统碳排放量进行测算的基础上,运用非参数核密度方法对中国西北干旱地区农牧业生态系统碳排放的演变趋势进行分析,研究发现:中国西北地区农牧业生态系统碳排放总量增势强劲,但空间非均衡性特征明显,以新疆最高,甘肃次之,陕西和青海居中,宁夏最低,农牧业碳排放源从以畜牧业为主向以种植业为主转变;西北地区农牧业碳排放强度呈下降趋势,省域差距明显,碳排放强度由大到小排序依次是:青海宁夏甘肃新疆陕西。从考察期内西北干旱地区农牧业碳排放的地区差距来看,整体上呈扩大趋势,但相对微弱的变化态势则反映了其变化幅度相对有限,其原因在于四种碳排放的变化趋势不一致,具体表现为:农田土壤碳排放的地区差距明显扩大;农用物资碳排放的地区差距在大幅扩大的同时,还表现出峰值从陡峭变为平缓,变化区间大幅扩大的现象;牲畜肠道发酵碳排放地区差距大幅缩小;牲畜粪便碳排放的地区差距也明显缩小。     

线粒体DNA多态性揭示丝绸之路上游地区少数民族的基因融合

河西走廊位于中国古丝绸之路的上游地区,是连接东亚和中亚地区的主要通道．为了在遗传背景上评价该地区的基因融合,研究了该地区5个少数民族人群的线粒体DNA多态性,采用测序和PCR－限制性内切酶片段长度多态分析方法对采自河西走廊地区的三个人群和邻近的新疆两个人群总共242个无关个体进行单倍型分型,并且把得到的数据同以前报道的东亚、中亚、西亚以及欧洲人群数据进行比较．结果发现欧洲特异单倍型和东亚特异单倍型同时存在于河西走廊地区人群中,从而揭示了从欧洲经中亚向河西走廊的基因流动．河西走廊地区人群在遗传上分布于中亚和东亚人群之间,这意味着中亚和东亚人群对该地区的母系遗传结构做出了重要贡献,本研究更加完整地展示了沿着丝绸之路地区从欧洲经中亚到丝绸之路上游的河西走廊的基因流动和基因融合事件。     

根田鼠的生物能学研究

根田鼠的生物能学研究侯建军北京师范大学生物系北京１００８７５根田鼠（Ｒｏｏｔｖｏｌｅ,Ｍｉｃｒｏｔ。。ｃｏ。ｍ。）比较广泛地分布于欧亚大陆北部地区。在我国主要分布于青海、四川、陕西、甘肃、宁夏和新疆等地（门。世居高寒地区草甸带,在青海海北高寒草甸生态...     

‘Arab invasion’ and decline,or the import of European racial thought by Iranian nationalists

Historical research on western racial theories has grown exponentially in the past few years. A number of scholars have also investigated various cases of ethnic prejudice beyond the western pale, for instance against Koreans in Japan or Muslims in India. Yet, little attention has been given to the modalities in which European nineteenth-century racial thought was adopted in other parts of the world. This article attempts to broach a discussion on this under-analysed aspect of race studies by reviewing one case, that of Arab-hatred in modern Iran. I argue that the intense hatred of Arabs in Iranian nationalist texts derives from a racialized vision of Iranian history born in nineteenth-century European texts. Racialized historiography was selectively imported by the ideologues of Iranian nationalism as it allowed them to explain Iran's weakness in terms of a loss of racial purity.     

Brief communication: two-rooted lower canines--a European trait and sensitive indicator of admixture across Eurasia

With the exception of Carabelli's trait, the European dentition is better known for the morphological traits that it does not exhibit rather than the ones that it does. One root trait, however, runs counter to the characterization of reduced and simplified European crowns and roots. Although a rare trait in general, two-rooted lower canines are much more common in Europeans than in any other regional grouping and, given adequate sample sizes, can be useful in evaluating gene flow between Europeans and neighboring groups. In European samples, two-rooted lower canines consistently exhibit frequencies of 5-8%. In our sample from northern Spain, the trait attains a frequency of almost 10%. In contrast, in Sub-Saharan Africans the trait is virtually unknown while in Asian and Asian-derived populations, it varies between 0.0 and 1.0%. Here we show that two-rooted canine frequencies for new migrants along the western frontiers of China and Mongolia ranged from 0-4%. These data suggest European-derived populations migrated into western China (Xinjiang Province) and Mongolia (Bayan Olgii Aimag) sometime during the late Bronze age (1000-400 BCE).     

No apparent reduction of gene flow in a hybrid zone between the West and North European karyotypic groups of the common shrew, Sorex araneus

The common shrew, Sorex araneus, exhibits an unusually high level of karyotypic variation. Populations with identical or similar karyotypes are defined as chromosome races, which are, in turn, grouped into larger evolutionary units, karyotypic groups. Using six microsatellite markers, we investigated the genetic structure of a hybrid zone between the Sidensjö and Abisko chromosome races, representatives of two distinct karyotypic groups believed to have been separated during the last glacial maximum, the West European karyotypic group (western group) and the North European karyotypic group (northern group), respectively. Significant F_ST values among populations suggest some weak genetic structure. All hierarchical levels show similar levels of genetic differentiation, equivalent to levels of genetic structure in several intraracial studies of common shrew populations from central Europe. Notably, genetic differentiation was of the same order of magnitude between and within karyotypic groups. Although the genetic differentiation was weak, the correlation between genetic and geographical distance was positive and significant, suggesting that the genetic variation observed between populations is a function of geographical distance rather than racial origin. Hence, considerable chromosomal differences do not seem to prevent extensive gene flow.     

The western and eastern roots of the Saami--the story of genetic "outliers" told by mitochondrial DNA and Y chromosomes

The Saami are regarded as extreme genetic outliers among European populations. In this study, a high-resolution phylogenetic analysis of Saami genetic heritage was undertaken in a comprehensive context, through use of maternally inherited mitochondrial DNA (mtDNA) and paternally inherited Y-chromosomal variation. DNA variants present in the Saami were compared with those found in Europe and Siberia, through use of both new and previously published data from 445 Saami and 17,096 western Eurasian and Siberian mtDNA samples, as well as 127 Saami and 2,840 western Eurasian and Siberian Y-chromosome samples. It was shown that the “Saami motif” variant of mtDNA haplogroup U5b is present in a large area outside Scandinavia. A detailed phylogeographic analysis of one of the predominant Saami mtDNA haplogroups, U5b1b, which also includes the lineages of the “Saami motif,” was undertaken in 31 populations. The results indicate that the origin of U5b1b, as for the other predominant Saami haplogroup, V, is most likely in western, rather than eastern, Europe. Furthermore, an additional haplogroup (H1) spread among the Saami was virtually absent in 781 Samoyed and Ob-Ugric Siberians but was present in western and central European populations. The Y-chromosomal variety in the Saami is also consistent with their European ancestry. It suggests that the large genetic separation of the Saami from other Europeans is best explained by assuming that the Saami are descendants of a narrow, distinctive subset of Europeans. In particular, no evidence of a significant directional gene flow from extant aboriginal Siberian populations into the haploid gene pools of the Saami was found.     

The accretion model of Neandertal evolution

The Accretion model of Neandertal evolution specifies that this group of Late Pleistocene hominids evolved in partial or complete genetic isolation from the rest of humanity through the gradual accumulation of distinctive morphological traits in European populations. As they became more common, these traits also became less variable, according to those workers who developed the model. Its supporters propose that genetic drift caused this evolution, resulting from an initial small European population size and either complete isolation or drastic reduction in gene flow between this deme and contemporary human populations elsewhere. Here, we test an evolutionary model of gene flow between regions against fossil data from the European population of the Middle and Late Pleistocene. The results of the analysis clearly show that the European population was not significantly divergent from its contemporaries, even in a subset of traits chosen to show the maximum differences between Europeans and other populations. The pattern of changes, over time within Europe of the traits in this subset, does not support the Accretion model, either because the characters did not change in the manner specified by the model or because the characters did not change at all. From these data, we can conclude that special phenomena such as near-complete isolation of the European population during the Pleistocene are not required to explain the pattern of evolution in this region.     

EVOLUTION AND POPULATION STRUCTURE OF AFRICANIZED HONEY BEES IN BRAZIL: EVIDENCE FROM SPATIAL ANALYSIS OF MORPHOMETRIC DATA

In recent years, studies based on isoenzymatic patterns of geographic variation have revealed that what is usually called the Africanized honey bee does not constitute a single population. Instead, several local populations exist with various degrees of admixture with European honey bees. In this paper, we evaluated new data on morphometric patterns of Africanized honey bees collected at 42 localities in Brazil, using univariate and multivariate (canonical) trend surface and spatial autocorrelation analyses. The clinal patterns of variation found for genetically independent characters (wing size characters and some wing venation angles) are concordant with previous studies of malate dehydrogenase (MDH) allelic frequencies and support the hypothesis that larger honey bees in southern and southeastern Brazil originated by racial admixture in the initial phases of African honey bee colonization. Geographic variation patterns of Africanized honey bee populations reflect a demic diffusion process in which European genes were gradually lost because of the higher fitness of the African gene pool in Neotropical environmental conditions.     

The barriers to oceanic island radiation in bryophytes: insights from the phylogeography of the moss Grimmia montana

Aim In contrast to angiosperms, bryophytes do not appear to have radiated in Macaronesia and the western Mediterranean. We evaluate if: (1) the apparent lack of radiation in bryophytes reflects our failure to recognize cryptic endemic species; (2) bryophytes are characterized by extremely low evolutionary rates; or (3) bryophytes have a high dispersal ability, which prevents genetic isolation. Location Worldwide, with a special emphasis on Macaronesia and the western Mediterranean. Methods Three chloroplast regions were sequenced from samples of the moss Grimmia montana from its entire distribution range. Network analyses, Fst and Nst statistics were used to describe and interpret the phylogeographical signal in the data. Results Despite significant phylogeographical signal in the chloroplast genome, which demonstrates limits to gene flow at the continental scale, repeated sister group relationships observed among accessions from different geographical areas suggest recurrent colonization patterns. These observations are consistent with mounting evidence that intercontinental distributions exhibited by many bryophyte species result from long‐distance dispersal rather than continental drift. Madeiran and western Mediterranean island haplotypes are either shared by, or closely related to, European and North American ones. Fst values between Madeira, western Mediterranean islands, North America and Europe are not significantly different from zero, and suggest that Madeira and the south‐western Mediterranean are subject to strong transatlantic gene flow. By contrast, haplotypes found in the Canary Islands are shared or closely related to those of populations from south‐western Europe or southern Africa. Main conclusions Multiple origins and colonization events are not consistent with the hypothesis of a relictual origin of the Macaronesian moss flora. One possible reason for the failure of taxa that experienced multiple colonization events to radiate is niche pre‐emption. We suggest that strong gene flow, coupled with the occupancy of all suitable niches, either by earlier conspecific colonizers or by other species, could be the mechanism preventing island radiation in G. montana and other cryptogams with high long‐distance dispersal abilities.     

A rapid PCR-SSP assay for the hemochromatosis-associated Tyr250Stop mutation in the TFR2 gene

Several genes associated with hemochromatosis and primary iron overload have been identified. Mutations in the HFE gene have been detected in 60-100% of hemochromatosis patients of northern, central, and western European descent, although the frequencies of these mutations vary among racial and ethnic groups. Recently, a mutation in the gene encoding transferrin receptor-2 (exon 6, nucleotide 750 C --> G; Y250X) was detected by a PCR-restriction fragment length polymorphism (RFLP) method in Sicilians with hemochromatosis. We describe a modification of the original assay in which the sequence-specific priming PCR assay does not require the use of restriction endonuclease. The modified assay is robust and cost-efficient, and may be more useful for large-scale population studies because it can be performed rapidly on DNA extracted from buccal swabs.