THE GENUS GIGANTASPIS HEINTZ, 1962 (VERTEBRATA, HETEROSTRACI) FROM THE LOWER DEVONIAN OF SPITSBERGEN

Abstract:  Material collected in 1969 by the CNRS-MNHN expedition to Spitsbergen includes a new species of Gigantaspis , G. minima , which is the smallest known species of this genus. The revision of Gigantaspis leads to the inclusion of Zascinaspis laticephala Blieck and Goujet in this genus. The phylogenetic analysis presented herein suggests that Gigantaspis is close to Zascinaspis , as suggested by Blieck. Moreover, it is also close to generalized representatives of the Protaspididae. Their shared character states allow the definition of a possible ancestral morphotype for the Protaspididae.     

UNDERSTANDING THE POPULATION GENETIC STRUCTURE OF GLEDITSIA TRIACANTHOS L.: THE SCALE AND PATTERN OF POLLEN GENE FLOW

Spatial and temporal patterns of gene flow determine the extent to which populations can differentiate from one another as a result of natural selection or genetic drift. In this study, we investigated pollen-mediated gene flow in two eastern Kansas populations of the subdioecious tree species, Gleditsia triacanthos L. (Leguminosae), or honeylocust. In 2 yr at each site, we used paternity-exclusion analysis to estimate the proportion of seeds sired by immigrant pollen. We also used a single-parent and parent-pair exclusion analysis on naturally established seedlings and saplings to estimate gene flow into one site over a 12-yr period and into the second site over a 22-yr period. Results of both analyses showed high minimum estimates of pollen gene flow into each site (17%–30%). In each population, we found significantly less gene flow in years of high fruit production than in years of low fruit production, but in one population, we observed little variation in gene-flow rates among age classes of seedlings and saplings. The level of pollen gene flow showed weak negative dependence on the relative isolation distances of the maternal trees sampled (140–240 m at one site vs. 85–120 m at the second site), and gene-flow estimates from naturally established juveniles were very similar at the two sites. Within populations, a multiple regression model showed that maximum-likelihood estimates of male fertility were negatively associated with distances between mates and positively associated with male size as measured by stem diameter. In neither population, however, did the regression explain more than 16% of the total variation in male fertilities.     

THE HISTORICAL PATTERN OF GENE FLOW AMONG MIGRATORY AND NONMIGRATORY POPULATIONS OF PRAIRIE WARBLERS (AVES: PARULINAE)

Within a group of interbreeding organisms, the balance of gene flow among populations and microevolutionary forces acting within populations is expected to result in clinal transitions in the phenotypes possessed by members of differentiated populations. Discontinuous variation between geographically adjacent populations suggests the presence of a significant barrier to gene flow. Here I present genetic evidence for restricted gene flow between migratory and nonmigratory populations of prairie warblers. The nonmigratory form of this species is restricted to coastal mangroves in Florida and is morphologically distinguishable from the typical, migratory form that occurs across the remainder of the eastern United States. Pairs of migratory populations exhibited little population subdivision (Φ_ST ? 0.09), whereas pairs of migratory and nonmigratory populations are much more differentiated (Φ_ST = 0.27–0.42). A phylogenetic analysis of mitochondrial DNA haplotypes did not offer evidence of long-term isolation of migratory and nonmigratory populations. Together with the population genetic analysis, the phylogenetic relationship of haplotypes suggests that isolation between these forms must have arisen relatively recently in their history. Evidence for significant population structure is unexpected, given the geographic proximity of migratory and nonmigratory populations, the capacity for long-distance movements (e.g., migration) by prairie warblers, and several previous studies of population structure in North American birds. However, the findings are consistent with the geographic distribution of morphological and behavioral variation and demonstrate that significant boundaries between populations of vagile organisms may be relatively cryptic.     

FLOW CYTOMETRIC ANALYSIS OF SPERMATOGENESIS IN THE DIATOM THALASSIOSIRA WEISSFLOGII (BACILLARIOPHYCEAE)1

Flow cytometry was used to detect and quantify sexual differentiation in the centric diatom Thalassiosira weissflogii (Grun.). Size (light scatter), chlorophyll, protein and DNA contents were measured for each cell throughout the process of differentiation. Male gametes were small round cells characterized by one complement of DNA and a lower protein and chlorophyll content than vegetative cells. Male gamete formation was induced by a long period of darkness (2 days) followed by a transfer to continuous light. Up to 30% of the initial cell population produced male gametes which appeared in the culture 14 h after release from darkness. Male gamete production was also detected in exponentially growing cultures in continuous light, but to a much smaller degree.     

利用流式细胞术研究大肠埃希菌对肝癌腹水瘤细胞系Hca—F25／CL—16A3的作用

利用小鼠肝癌腹水瘤细胞Hca-F25/CL-16A3,运用流式细胞技术研究了大肠埃希菌对肿瘤细胞的作用,对细胞DNA含量的影响以及诱导细胞凋亡的作用,结果表明：大肠埃希菌在直接希伤肿瘤细胞的同时,还可以影响细胞DNA的含量,并可诱导细胞发生调亡。     

中国画眉科鸟类分布格局探讨

中国现有画眉科鸟类122种,隶属于27属,占我国鸟类总种数的9.15%。通过运用GIS技术处理物种分布数据,研究了中国画眉科鸟类的分布格局和多样性中心。中国画眉科鸟类在水平分布上具有不均匀性,省际单元上云南最多(102种),占绝对优势;在动物地理亚区单元上滇南山地亚区分布最多(80种),其次是西南山地亚区(60种)、喜马拉雅亚区(47种);在垂直分布上,则以700～2700m的海拔地带具有最高的物种多样性。中国画眉科鸟类物种多样性最高的地区位于滇南山地亚区与西南山地亚区的交汇地带—横断山区南端。我国画眉科鸟类主要涉及以下3个分布型:东洋型、喜马拉雅-横断山型和南中国型。     

高原裸裂尻鱼头部轮廓形状及其变异的几何形态测量分析

为了明确描述高原裸裂尻鱼的表型多样性,运用现代几何形态测量法,基于高原裸裂尻鱼头部轮廓的形态坐标数据,对其5个地理种群的样本做了定量分析。结果主要如下:①主成分分析（PCA）和典型变量分析（CVA）显示,5个地理种群的样本的变异主要位于口型特征、下吻部形状、下颌骨形状、下颌锐利角质程度和头部形状等性状。②基于主成分分析、典型变量分析和聚类分析,高原裸裂尻鱼三个亚种（班公湖亚种、玛法木湖亚种和指名亚种）相互分开,在PC1轴上从负值到正值依次排列,从而确定了高原裸裂尻鱼亚种划分的有效性。③通过形态差异的显著性检验,基于马氏距离和普氏距离分析了高原裸裂尻鱼各地理种群之间的形态变异距离,根据差异显著性将该5个地理种群的高原裸裂尻鱼分为湖泊型亚种和河流型亚种,随后的聚类分析同样支持该结果。总之,通过几何形态测量法,准确描述了高原裸裂尻鱼头部轮廓的形态多样性,按照外形的差异,将5个地理种群分为两种生态型,并推测该差异主要是由于所生活的水体环境和食物差异所造成。对高原裸裂尻鱼形态差异的识别和研究,能为其生态学研究和物种多样性保护提供相应指导,丰富微进化理论。     

A NEW DIPNOAN FISH FROM THE MIDDLE DEVONIAN (EIFELIAN) OF SCOTLAND

Abstract:  A new dipnoan fish, Pinnalongus saxoni gen. et sp. nov., is described from a suite of recently discovered specimens from Caithness and East Sutherland, northern Scotland. The stratum where Pinnalongus occurs is within the middle Eifelian of the Middle Devonian. Pinnalongus has a skull roof consisting of a mosaic of small bones at the anterior end, a feature more typically found in Early Devonian dipnoans. The posterior part of the skull roof is more typical of later advanced Middle Devonian dipnoans with the B-bone separating the I-bones. The postcranial body is now considered not to be so important with respect to the classification of dipnoans as originally proposed by Dollo in 1895, who thought there was an evolutionary transformation series. Nevertheless, the postcranial body of Pinnalongus has more in common with later Middle and Late Devonian dipnoans such as Scaumenacia , with a very long second dorsal fin. Based on the skull morphology, Pinnalongus is most closely related to Tarachomylax from the Lower Devonian of Severnaya Zemlya, Russia. Pinnalongus represents the earliest known complete articulated dipnoan with tooth plates.     

THE EURYPTERID ADELOPHTHALMUS SIEVERTSI (CHELICERATA: EURYPTERIDA) FROM THE LOWER DEVONIAN (EMSIAN) KLERF FORMATION OF WILLWERATH, GERMANY

Abstract: The eurypterid Rhenopterus sievertsi Størmer from the Lower Devonian of Germany is redescribed. Based on new morphological data, including the possession of prosomal limbs of Adelophthalmus‐type and spatulae on the genital operculum, the species is transferred to Adelophthalmus Jordan, in Jordan and von Meyer and thus is the oldest representative of this geographically and stratigraphically widespread genus. Eurypterus? trapezoides Størmer is recognized as a junior synonym of A. sievertsi.     

胃粘膜血流量对大鼠胃粘膜适应性细胞保护作用的影响

采用氢气清除法测定胃粘膜血流量,观察大鼠胃内灌洗低浓度盐酸酒精后灌注高浓度盐酸酒精（０．６ｍｏｌ／ＬＨＣｌ＋１５％ＥｔＯＨ）对ＧＭＢＦ和胃粘膜损害的影响。以及ＧＭＢＦ在适应性细胞保护中的作用。结果如下：（１）先用低浓度盐酸酒精作为弱刺激灌注随之以高浓度盐酸酒精作为强刺激灌注,引起胃粘膜适应性保护现象,它表现为：大体操作和损伤深度分别比单独泊组减少４７．０９％和４４．５７％应性现象,它表现为：大体损     

PHYLOGEOGRAPHY OF SPOTTED OWL (STRIX OCCIDENTALIS) POPULATIONS BASED ON MITOCHONDRIAL DNA SEQUENCES: GENE FLOW,GENETIC STRUCTURE,AND A NOVEL BIOGEOGRAPHIC PATTERN

Mitochondrial DNA control region sequences of spotted owls (Strix occidentalis) allowed us to investigate gene flow, genetic structure, and biogeographic relationships among these forest-dwelling birds of western North America Estimates of gene flow based on genetic partitioning and the phylogeography of haplotypes indicate substantial dispersal within three long-recognized subspecies. However, patterns of individual phyletic relationships indicate a historical absence of gene flow among the subspecies, which are essentially monophyletic. The pattern of haplotype coalescence enabled us to identify the approximate timing and direction of a recent episode of gene flow from the Sierra Nevada to the northern coastal ranges. The three subspecies comprise phylogenetic species, and the northern spotted owl (S. o. caurina) is sister to a clade of California (S. o. occidentalis) plus Mexican spotted owls (S o lucida); this represents a novel biogeographic pattern within birds. The California spotted owl had substantially lower nucleotide diversity than the other two subspecies; this result is inconsistent with present patterns of population density A causal explanation requires postulating a severe bottleneck or a selective sweep, either of which was confined to only one geographic region.     

POPULATION STRUCTURE AND LEVELS OF GENE FLOW IN THE MEDITERRANEAN LAND SNAIL ALBINARIA CORRUGATA (PULMONATA: CLAUSILIIDAE)

The amount of gene flow among local populations partly determines the relative importance of genetic drift and natural selection in the differentiation of such populations. Land snails, because of their limited powers for dispersal, may be particularly likely to show such differentiation. In this study, we directly estimate gene flow in Albinaria corrugata, a sedentary, rock-dwelling gastropod from Crete, by mark-recapture studies. In the same area, 23 samples were taken and studied electrophoretically for six polymorphic enzyme loci. The field studies indicate that the population structure corresponds closely to the stepping-stone model: demes are present on limestone boulders that are a few meters apart, and dispersal takes place mainly between adjacent demes. Average deme size (N) is estimated at 29 breeding individuals and the proportion of migrants per generation at 0.195 (Nm = 5.7). We find no reason to assume long-distance dispersal, apart from dispersal along occasional stretches of suitable habitat. Genetic subdivision of the population, as derived from F_ST values, corresponds to the direct estimate only at the lowest spatial level (distance between sample sites < 10 m), where values for Nm of 5.4 and 17.6 were obtained. In contrast, at the larger spatial scales, F_ST values give gene-flow estimates that are incompatible with the expected amount of gene flow at these scales. We explain these discrepancies by arguing that gene flow is in fact extremely limited, making correct estimates of Nm from F_ST impossible at the larger spatial scales. In view of these low levels of gene flow, it is concluded that both genetic drift and natural selection may play important roles in the genetic differentiation of this species, even at the lowest spatial scales.     

VOLVOX BARBERI,THE FASTEST SWIMMER OF THE VOLVOCALES (CHLOROPHYCEAE)1

Volvox barberi W. Shaw is a volvocalean green alga composed of biflagellated cells. Vovocales with 16 cells or more form spherical colonies, and their largest members have germ‐soma separation (all species in the genus Volvox). V. barberi is the largest Volvox species recorded in terms of cell number (10,000–50,000 cells) and has the highest somatic to reproductive cell ratio (S/R). Since they are negatively buoyant, Volvocales need flagellar beating to avoid sinking and to reach light and nutrients. We measured V. barberi swimming speed and total swimming force. V. barberi swimming speeds are the highest recorded so far for volvocine algae (～600 μm · s^?1). With this speed, V. barberi colonies have the potential to perform daily vertical migrations in the water column at speeds of 2–3 m · h^?1, consistent with what has been reported about Volvox populations in the wild. Moreover, V. barberi data fit well in the scaling relationships derived with the other smaller Volvox species, namely, that the upward swimming speed V_up∝N^0.28 and the total swimming force F_S∝N^0.77 (N = colony cell number). These allometric relationships have been important supporting evidence for reaching the conclusion that as size increases, colonies have to invest in cell specialization and increase their S/R to increase their motility capabilities to stay afloat and motile.     

粉虱蚜属蚜虫的分布格局及其成因探讨(同翅目:扁蚜科)

本文以世界分布的 5种粉虱蚜属AleurodaphisvanderGoot蚜虫为材料 ,研究了该属的地理分布特点 ,现代分布格局及可能的起源。同时 ,利用蚜虫与寄主植物协同进化的关系 ,并结合古地理和古生物等方面的资料 ,探讨了粉虱蚜属的现代分布格局形成的可能原因。粉虱蚜属为典型的东洋区成分 ,但在中国大陆其分布向古北界有所渗透。根据该属蚜虫现代分布特点 ,推测中国的华中区是该属的现代分化中心。另外 ,推测形成该属现代分布格局的原因可能是由于各大陆之间的接合与分离     

云南早泥盆世西山村组华南鱼类的首次发现

记述了云南曲靖地区早泥盆世洛霍考夫期华南鱼类一新属———王冠鱼(Stephaspis gen.nov.)。新属发现于西山村组下部致密坚硬的石英砂岩中,其主要特征是:个体较大的华南鱼类,头甲呈长盾形,后缘向后凸出;角发育,侧向延伸,末端向头甲后侧方自然倾斜,内角不发育;具吻突,但不甚发育;中背孔较大,呈纵向椭圆形,前端稍尖,后端圆钝;眶孔较小,圆形,背位;头甲背面具一对背窗,呈狭长椭圆形,靠近头甲侧缘;感觉管系统不甚发育,仅见后眶上管、侧背管、侧横管及背联络管,后眶上管呈V字形;纹饰为细小的粒状瘤点。新属不仅是华南鱼类在西山村组的首次发现,也指示了目前华南鱼类出现的最低层位,为探讨华南鱼类的起源与早期辐射提供了重要资料。     

鼎突多刺蚁蚁群的空间和时间动态

本文对鼎突多刺蚁野外群体的空间格局、蚁群品级结构及其时间动态等方面作了研究。     

LECLERCQIA COMPLEXA (LYCOPSIDA,MIDDLE DEVONIAN): ITS ANATOMY,AND THE INTERPRETATION OF PYRITE PETRIFACTIONS

The development and/or modification of special acid etching and macerating techniques permits pyritized fossils of Leclercqia complexa to be separated into their carbonaceous wall remains and pyrite lumen—pit casts. These carbonized and pyritic portions can then be studied separately by both light and SEM microscopy and information from both modes compared with that obtainable from carbonaceous compression fossils of L. complexa. This combination of techniques, preservation modes and methods of analysis, allows a synthesis of information obtainable from each, as well as providing a check on errors of interpretation due to preservation mode and method of observation. The developmental sequence of the secondary wall thickenings of the protoxylem elements is shown to be annular to connected annular and spiral, with both exarch and mesarch maturation. The metaxylem shows a transition through reticulate to multiseriate round, oval, and elongate bordered-pitted tracheids. Different wall facets of separated pyrite tracheid casts can be examined by the SEM and variations in wall structure and pitting characterized. Cells of the outer cortex are 6 to 10 times longer than wide, have thickened vertical walls and end walls that vary from nearly horizontal to angles of overlap of 50 degrees.     

中国水蛇Enhydris chinensis （Gray）生殖周期与生殖型式的研究

中国水蛇于7月末8月初精子发生开始新的周期性复生,大部分为精母细胞。10—12月以至次年1月初大部分为成熟精子及变态中的精细胞,精子贮于附睾或输精管中过冬。11月至次年5月大部分输卵管中也存有精子。雌水蛇一年一次排卵,卵胎生。5月末至6月初见有蛇胚,孕妊期78—84天,8月中旬至9月中旬产仔蛇,每胎产仔6—21条。     

GENE FLOW,REFUGIA, AND EVOLUTION OF GEOGRAPHIC VARIATION IN THE SONG SPARROW (MELOSPIZA MELODIA)

We surveyed mtDNA restriction-site variation in song sparrows taken from across their continental range. Despite marked geographic variation in size and plumage color, mtDNA variation was not geographically structured. Subspecies were not identifiable by mtDNA analysis. We suggest that postglaciation dispersal scattered mtDNA haplotypes across the continent, explaining the lack of mtDNA geographic patterns. Evolution of size and plumage coloration has probably proceeded faster than mtDNA evolution, leading to the well-structured continental pattern of morphological variation. We suggest that the nonordered geographic distribution of haplotypes reflects the recency of population establishment following completion of range expansion. Dispersal distance was estimated from the mtDNA data at 6.1 km per generation, an order of magnitude greater than that (0.3 km) estimated from demographic data. Island samples were not especially different from continental ones. Rooting the haplotype cladogram with a putative primitive haplotype identified Newfoundland and the Queen Charlotte Islands as potential sites of recent refugia. We question whether study of geographic variation in song sparrows leads to insights concerning speciation.     

从底栖生物化石再释贵州独山泥盆系龙洞水段的时代

贵州独山的猴儿山组龙洞水段是一套浅海相碳酸盐沉积,盛产底栖牛物化石.通过对该段地层中所含四射珊瑚、床板珊瑚和腕足类等化石属种的详尽分析,再次证实龙洞水段的地质时代仍应属中泥盆世早期(Eifelian).而不是像某些根据痕迹化石或层序地层学的研究那样将它置于下泥盆统.