南海中部浮游有孔虫通量的季节变化

南海中部１９９３－１９９５年连续两年的浅层和深层时间系列沉积捕获器试验,揭示游游有孔虫总通量以及Ｇlobigerinoides saculifer,Globigerinoides ruber,Neogloboquadrina dutertrei,Globigerinita glutinata等种的通量和相对百分数在东北季风和西南季风盛行期出现高值,而Globigerina bulloides,Pulleniatina obiquiloculata和Globorotalia menardii等种则仅在冬东北季风盛行期出现高值。此外,还发现浮游有孔虫属种的通量呈现明显的年际变化,研究表明这种季节和和年际变化主要受与东亚季风相关的表层初级生产力和海洋水文条件变化的控制。     

Palaeoceanographic implications of genetic variation in living North Atlantic Neogloboquadrina pachyderma

The shells of the planktonic foraminifer Neogloboquadrina pachyderma have become a classical tool for reconstructing glacial-interglacial climate conditions in the North Atlantic Ocean. Palaeoceanographers utilize its left- and right-coiling variants, which exhibit a distinctive reciprocal temperature and water mass related shift in faunal abundance both at present and in late Quaternary sediments. Recently discovered cryptic genetic diversity in planktonic foraminifers now poses significant questions for these studies. Here we report genetic evidence demonstrating that the apparent 'single species' shell-based records of right-coiling N. pachyderma used in palaeoceanographic reconstructions contain an alternation in species as environmental factors change. This is reflected in a species-dependent incremental shift in right-coiling N. pachyderma shell calcite delta18O between the Last Glacial Maximum and full Holocene conditions. Guided by the percentage dextral coiling ratio, our findings enhance the use of delta18O records of right-coiling N. pachyderma for future study. They also highlight the need to genetically investigate other important morphospecies to refine their accuracy and reliability as palaeoceanographic proxies.     

Past temperature and delta18O of surface ocean waters inferred from foraminiferal Mg/Ca ratios

Determining the past record of temperature and salinity of ocean surface waters is essential for understanding past changes in climate, such as those which occur across glacial-interglacial transitions. As a useful proxy, the oxygen isotope composition (delta18O) of calcite from planktonic foraminifera has been shown to reflect both surface temperature and seawater delta18O, itself an indicator of global ice volume and salinity. In addition, magnesium/calcium (Mg/Ca) ratios in foraminiferal calcite show a temperature dependence due to the partitioning of Mg during calcification. Here we demonstrate, in a field-based calibration experiment, that the variation of Mg/Ca ratios with temperature is similar for eight species of planktonic foraminifera (when accounting for Mg dissolution effects). Using a multi-species record from the Last Glacial Maximum in the North Atlantic Ocean we found that past temperatures reconstructed from Mg/Ca ratios followed the two other palaeotemperature proxies: faunal abundance and alkenone saturation. Moreover, combining Mg/Ca and delta18O data from the same faunal assemblage, we show that reconstructed surface water delta18O from all foraminiferal species record the same glacial-interglacial change--representing changing hydrography and global ice volume. This reinforces the potential of this combined technique in probing past ocean-climate interactions.     

The cost of inbreeding in Arabidopsis

Population geneticists have long sought to estimate the distribution of selection intensities among genes of diverse function across the genome. Only recently have DNA sequencing and analytical techniques converged to make this possible. Important advances have come from comparing genetic variation within species (polymorphism) with fixed differences between species (divergence). These approaches have been used to examine individual genes for evidence of selection. Here we use the fact that the time since species divergence allows combination of data across genes. In a comparison of amino-acid replacements among species of the mustard weed Arabidopsis with those among species of the fruitfly Drosophila, we find evidence for predominantly beneficial gene substitutions in Drosophila but predominantly detrimental substitutions in Arabidopsis. We attribute this difference to the Arabidopsis mating system of partial self-fertilization, which corroborates a prediction of population genetics theory that species with a high frequency of inbreeding are less efficient in eliminating deleterious mutations owing to their reduced effective population size.     

Molecular biological research on Foraminifera

ForaminiferabelongstoSarcodina(Protozoa)andexhibitscytoplasmicorganizationandpseudopdial streamingcharacteristicbroadlyofamoeboidorgan ism[1].Itmainlylivesinthemarineenvironment withamembranous,agglutinatedorcalcareousshell.Asoneofthemostimportantgroupsinmicropaleon tology,Foraminiferahasbeenwidelyusedforthe stratigraphicsubdivision,correlationinpetroleum wellsandforthereconstructionofpaleo environments duringthelastseveraldecades[2,3].Furthermore,sincethe1960swiththestartofDeepSeaDrilling …     

Molecular biological research on Foraminifera

As one of the most important groups in micropaleontology, Foraminifera is traditionally described to have a membranous, agglutinated or carbonate shell according to its morphology, which resembles the marine granuloreticuloseans. However, recent molecular analyses on its ribosomal RNA gene have disclosed the existence of the naked, and also freshwater and terrestrial species. Foraminiferal SSU rDNA sequence suggests that this group is positioned at the base of the Eukaryotes phylogenetic trees, between Euglenoida and Diplomonadida. Existence of a large amount of genetic types in planktonic foraminifera suggests an underestimation of the biodiversity for the nearly 50 species in world oceans and their close relationship with the ocean environment, such as bio-geographic distribution and water currents. This provides a more reliable proxy for future paleoenvironmental study.     

A broad deglacial δ13C minimum event in planktonic foraminiferal records in the Okinawa Trough

The equatorial Pacific upwelling zone has been suspected of playing an important role in the global atmospheric CO2 changes associated with glacial-interglacial cycles.In order to assess the influencing scope of the surface water deglacial δ13C minimum in the tropical Iow-latitude Pacific,the core DGKS9603, collected from the middle Okinawa Trough, was examined for δ13C records of planktonic foraminifera N. dutertrei and G. ruber. The planktonic foraminiferal δ13C records show a clear decreasing event from 20 to 6 cal. kaBP., which is characterized by long duration of about 14 ka and amplitude shift of 0.4 × 10-3. Its minimum value occurred at 15.7 cai kaBP. The event shows fairly synchrony with the surface water deglacial δ13C minimum identiffed in the tropical Pacific and its marginal seas. Because there is no evidence in planktonic foraminiferal fauna and δ18O records for upwelling and river runoff enhancement,the broad deglacial δ13C minimum event in planktonic foraminiferal records revealed in core DGKS9603 might have been the direct influencing result of the deglacial surface water of the tropical Pacific. The identification for the event in the Okinawa Trough provides new evidence that the water evolution in the tropical low-latitude Pacific plays a key role in large regional, even global carbon cycle.     

Benthic foraminiferal fauna turnover at 2.1 Ma in the northern South China Sea

Quantitative analysis of benthic foraminifera from ODP Site 1146 in the northern South China Sea (SCS) shows that abundance of Bulimina alazanensis, sometimes up to about 90%, decreased gradually since 3.2 Ma, especially at 2.1 Ma. Abundance of other benthic foraminiferal species, Globobulimina sub-globosa and Cibicidoides wuellerstorfi, increased after 2.1 Ma. Comparison with changes in oxygen and carbon isotopes of planktonic and benthic foraminifera shows that high abundance values of B. alazanensis corresponded with lower values of oxygen isotope, but for carbon isotope, high values of the species were consistent with heavier carbon isotope of benthic foraminifera and lighter carbon isotope of planktonic foraminifera, respectively, and vice versa. Considering factors such as uplift of Bashi Strait, expansion of the North Hemisphere Glaciation, strengthening of East Asian winter mon-soon and variations in oxygen and carbon isotope of foraminifera, changes of B. alazanensis in ODP Site 1146 suggest that the source of deep water masses of the northern South China Sea changed from the warm Pacific deep water with high oxygen content to Pacific Intermediate water with low oxygen content at 2.1 Ma. In addition, the strengthened East Asian winter monsoon resulted in increased pri-mary productivity, high nutrient and suboxic bottom water. Variations in species of B. alazanensis seemed to be unable to tolerate environmental stress induced by deep water masses and productivity changes.     

Warming magnitude of Indonesian Throughflow during the penultimate deglaciation (Termination II) and its relationship with climate change in high-latitude regions

The tropical oceans are important source areas for global heat and water vapor transport, and changes in tropical sea surface tem-perature (SST) will have important impacts on high-latitude and global climate change. It is crucial to establish the precise phase relationship between tropical and high-latitude climate variability to gain insight into the mechanisms of global climate change. Here, we present multi-proxy records across the penultimate deglaciation (Termination II) from sediment Core SO18459, which is located in the outflow area of the Indonesian Throughflow (ITF) of the Timor Sea. These proxy records include planktonic and benthic foraminifera δ¹⁸O, planktonic foraminifera G. ruber Mg/Ca-derived SST, and δ¹⁸O_w of sea surface water. The Mg/Ca-SST records indicate a warming of 4.1°C in the Timor Sea over Termination II, which is in phase with decrease in planktonic and benthic δ¹⁸O. Our results suggest that at millennial timescales, climate change of the tropical oceans is synchronous with high-latitude ice volume changes. Furthermore, warming of the Timor Sea is almost simultaneous with warming of the Antarctic, suggesting a rapid heat transfer from the tropics to the Antarctic via the atmosphere and/or ocean circulations. The G. ruber δ¹⁸O and SST records of Core SO18459 show a marked YD-like event during Termination II, which is probably caused by decrease in Australian rainfall or strengthening of the Western Pacific Warm Pool. However, a similar YD-like event is not observed in East Asian rainfall records. This discrepancy indicates that different tropical climate systems may have different responses to the same forcing, such as El Niño Southern Oscillation. A similar YD-like event is observed in the global benthic foraminiferal δ¹⁸O records during Termination II, implying teleconnection of millennial scale climate change between the tropical regions and high latitudes.     

1976年以来丹顶鹤在我国的分布变迁及就地保护状况

目的 了解近40年来丹顶鹤(Grus japonensis)在我国的主要分布情况及变化,探讨我国现阶段丹顶鹤的就地保护状况,分析丹顶鹤分布变迁的可能原因,为今后丹顶鹤的保护和研究提供理论基础。方法 基于1976年《中国鸟类分布名录》中记述我国丹顶鹤的分布情况,通过文献查询、部门咨询等方式,系统搜集丹顶鹤的历史分布资料,将分布信息按照时间顺序进行分类,分析丹顶鹤繁殖地、越冬地分布的时空变化特征,比较不同时间阶段丹顶鹤保护区的就地保护成效。结果 自1976年以来,我国丹顶鹤新的分布地在多个省区逐渐增加,截至2019年,有丹顶鹤分布记录的自然保护区达119个,分布在16个省区,丹顶鹤繁殖与越冬分布界限也发生了改变。其中,丹顶鹤繁殖分布区由以往广泛分布于我国东部区域转换为现在集中分布的繁殖地所在自然保护区,丹顶鹤越冬分布区由以往长江中下游的多地分布转换为现在的三地分布,即盐城湿地珍禽国家级自然保护区、黄河三角洲国家级自然保护区、辽河口国家级自然保护区。目前,全国已建立57个丹顶鹤保护区,国家级、省级、县市级自然保护区的数量分别为30、18、9个,各占总数的52.6%、31.6%、15.8%。结论 近40年来,我国丹顶鹤种群的新分布时有报道,其分布现状已经发生了较大变化。由此推测,人为因素的干扰与自然气候的变化是导致丹顶鹤分布变迁的主要原因,自然保护区的管理、其他突发事件也共同影响着丹顶鹤的分布。     

The evolution of alternative parasitic life histories in large blue butterflies

Large blue (Maculinea) butterflies are highly endangered throughout the Palaearctic region, and have been the focus of intense conservation research. In addition, their extraordinary parasitic lifestyles make them ideal for studies of life history evolution. Early instars consume flower buds of specific host plants, but later instars live in ant nests where they either devour the brood (predators), or are fed mouth-to-mouth by the adult ants (cuckoos). Here we present the phylogeny for the group, which shows that it is a monophyletic clade nested within Phengaris, a rare Oriental genus whose species have similar life histories. Cuckoo species are likely to have evolved from predatory ancestors. As early as five million years ago, two Maculinea clades diverged, leading to the different parasitic strategies seen in the genus today. Contrary to current belief, the two recognized cuckoo species show little genetic divergence and are probably a single ecologically differentiated species. On the other hand, some of the predatory morphospecies exhibit considerable genetic divergence and may contain cryptic species. These findings have important implications for conservation and reintroduction efforts.     

Carbon isotopic record of foraminifers in surface sediments from the South China Sea and its significance

Since the 1990s, the papers and data involved withthe South China Sea (SCS) have been emerging in largenumbers in the world as people pay more attention to thepaleoceanography of the SCS. There have been more than100 cores mentioned in papers containing p…     

Distribution,ecology, and oxygen and carbon isotope characteristics of modern planktonic foraminifers in the Makarov Basin of the Arctic Ocean

The Arctic region, with magnificent ice cover on the surface of the Arctic Ocean and adjacent seas, is not only extremely sensitive to but also has strong amplification effects on climate change. Observations during the past decades have documented substantial retreat and thinning of the Arctic sea-ice cover, a process that is accelerating. Its feedback and impact on the global climate has become an important subject of current climate change research. Calcite tests of planktonic foraminifers are major constituents in pelagic sediments, and they provide valuable materials for the reconstruction of past oceanographic conditions. However, research is still sparse in the Arctic sea area because of limited availability of the materials for investigation. Here, we present a study of modern foraminifers from the plankton tow samples taken in the Makarov Basin of the Arctic Ocean during the fourth Arctic expedition of China. We have analyzed ecological information stored in the modern planktonic foraminifers and in their stable isotope signals, and established a relationship between the distribution of the main taxa and the environment. Our main observations are as follows:(1) in the Makarov Basin, the polar species Neogloboquadrina pachyderma(sinistral coiling) dominates the [150 lm planktonic foraminiferal assemblages.(2) The planktonic foraminifers live mainly in the upper halocline at a water depth of 50–100 m and less in the depth interval of 100–200 m.(3) Temperature change in the halocline can affect the absolute abundance of planktonic foraminifers and their distribution in the water column. The warmer halocline is more favorable to the development of planktonic foraminifers.(4) A lighter d18O value(2.11 %) of N. pachyderma(sin.) is recorded in the depth interval of 100–200 m, which is likely related to the isotopically light brines separated out during sea ice freezing. The relatively heavy d18O value(1.68 %–2.68 %, average 2.27 %) in the depth interval of 50–100 m may be influenced by the low salinity water with the relatively heavy d18O value formed during the sea-ice melting in the surface layer.     

吉林省胡桃楸群落主要分布地区物种组成及区系分析

通过对吉林省胡桃楸群落主要分布地区调查数据的统计发现维管束植物共计58科137属186种.科、属、种数量均以延边地区最高,吉林地区次之,白山地区最少;物种组成的相似性以吉林-延边最高,延边-白山和吉林-白山相对较小;不同地区科、属组成均以单种科、单种属占优势,组成具有一定的分散性.各地区胡桃楸群落植物属的区系分布总体趋势比较一致,均以北温带分布为主,兼有部分热带分布类型,旧世界热带分布、东亚北美间断分布等也存在一定比例,说明该群落维管束植物的组成存在与热带早期的历史联系,具有较高的古老性和联系的广泛性;此外,作为胡桃楸群落区系的重要组成部分,世界分布类型反映了该群落是在漫长的地史年代中发展而来的次生性植被.吉林、延边、白山群落的T/R值分别为4.73,6.41,9.33,区系组成均表现出强烈的温带性质.     

Theory predicts the uneven distribution of genetic diversity within species

Global efforts to conserve species have been strongly influenced by the heterogeneous distribution of species diversity across the Earth. This is manifest in conservation efforts focused on diversity hotspots. The conservation of genetic diversity within an individual species is an important factor in its survival in the face of environmental changes and disease. Here we show that diversity within species is also distributed unevenly. Using simple genealogical models, we show that genetic distinctiveness has a scale-free power law distribution. This property implies that a disproportionate fraction of the diversity is concentrated in small sub-populations, even when the population is well-mixed. Small groups are of such importance to overall population diversity that even without extrinsic perturbations, there are large fluctuations in diversity owing to extinctions of these small groups. We also show that diversity can be geographically non-uniform--potentially including sharp boundaries between distantly related organisms--without extrinsic causes such as barriers to gene flow or past migration events. We obtained these results by studying the fundamental scaling properties of genealogical trees. Our theoretical results agree with field data from global samples of Pseudomonas bacteria. Contrary to previous studies, our results imply that diversity loss owing to severe extinction events is high, and focusing conservation efforts on highly distinctive groups can save much of the diversity.     

Independent transfer of mitochondrial chromosomes and plasmids during unstable vegetative fusion in Neurospora

The sporadic distribution of similar introns in organelle, nuclear ribosomal RNA and bacteriophage genes suggests that at least some of these introns are mobile genetic elements. Some plasmids in fungal mitochondria contain intron-like sequences and, like introns, they have scattered distributions within and among species. The occurrence and evolutionary importance of such horizontal transfer of DNA, not only between fungi, but among a wide range of organisms have been matters of much discussion. Here, we report experimental evidence for transfer of Neurospora mitochondrial plasmids from one mitochondrial genotype to another at high frequency during unstable vegetative cell fusion. Exchange of mitochondrial and nuclear genomes can also occur. These observations suggest that vegetative fusion may have a more important role in the mitochondrial genetic structure of natural populations than is generally thought, and may provide an explanation for the distribution of certain plasmids and possibly other mobile genetic elements.     

海洋生物中的隐藏生物多样性与物种形成:终生浮游生物悖论

隐种广泛存在于各类海洋生物中,尤其是底栖无脊椎动物.然而,海洋终生浮游生物由于具有较强的扩散能力,往往被视为生物多样性低、物种形成慢.本文就海洋终生浮游生物隐种与物种形成的研究作一综述.基于研究的38个种类,结果表明:1)海洋终生浮游生物普遍存在隐种,其物种形成要比想象得快;2)由于引种的广泛存在,形态种生物多样性无法反映海洋终生浮游生物真正的物种多样性;3)地理隔离有助于海洋终生浮游生物隐种的形成,但异域物种形成的作用仍值得商榷;4)生态物种形成很可能是海洋终生浮游生物物种形成的主流模式.海洋终生浮游生物强基因流下快速的物种形成有悖于生物进化常理,解决该悖论将有助于我们对海洋物种形成和生物多样性的理解.     

江西晒烟品种资源调查

江西是我国晒烟主要产区之一,栽培历史悠久,品种资源丰富.长期以来,未曾开展较深入的研究.我们赴全省晒烟主要产区,对品种资源进行实地调查,发现主要栽培品种分为3个类型共14个品种.我们对其生物学特性及其品种特点进行了观察研究,现加以报导,供烟草科技工作者和生产单位参考、利用,并为烟草育种和良种繁育提供可靠的品种资源.     

Wormy mice in a hybrid zone

As one approach to analysing the genetic barriers between species, we studied the numbers and types of parasitic worms in two species of house mice (Mus musculus and M. domesticus) and in their natural hybrids. Where the ranges of these two species meet in southern Germany, there is a zone of hybridization less than 20 kilometres across, in which about 98% of the mice have backcross genotypes. Fourteen of the 46 mice tested from within the zone have over 500 pinworms per gut, a number far exceeding the mean of 40 per gut for other mice inside and outside the zone. Other nematodes have a similar, non-random distribution. The number of mice bearing 9 or more tapeworms per gut is also excessive in the hybrid zone. These extraordinarily wormy mice may be unusually susceptible to parasitism; the different species may have different genes for resistance, and recombinant backcross animals may lose both. Our findings support the view that the hybrid populations may have reduced fitness and thereby act as a genetic sink, interfering with the flow of genes between the two species. The possibility that environmental or ecological peculiarites in the zone of hybridization make the mice more liable to infection is not supported.