A review of the biology and genetics of sea lice   总被引：5，自引：0，他引：5  

Boxaspen  Karin 《ICES Journal of Marine Science》2006,63(7):1304-1316

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Parentage determination of black sea bream(Acanthopagrus schlegelii) for stock enhancement:effectiveness and loss of genetic variation     

Binbin Shan  Yan Liu  Na Song  Changping Yang  Shengnan Liu  Tianxiang Gao  Dianrong Sun 《海洋学报(英文版)》2021,40(6):41-49

The stock enhancement programs for black sea bream Acanthopagrus schlegelii have been conducted in China for a fewyears.However,little information has been reported concerning the effectiveness and genetic effect of black sea bream stock enhancement.In order to detect the contribution of released individuals in Zhujiang River Estuary(ZRE) and Daya Bay(DB),six microsatellite markers were used to identify the hatchery-released individuals.In addition,this pedigree of hatchery populations(broodfish and hatchery-released offspring) was traced to detect the number of effective parents(N_e),the inbreeding coefficient and the decrease of genetic variability in the reproduction.The pedigree reconstruction showed that at least 69(out of 93) broodfish had offspring.The estimated N_e was 54.8,consequently the inbreeding coefficient was 0.91%.The genetic diversity of hatchery-released offspring was lower than that in that of broodfish(heterozygosity alleles,0.727-0.774),some alleles(number of alleles,61-69) and genetic variance were lost during reproduction.It was observed that wild samples had higher levels of genetic diversity compared with hatchery populations as well as recaptured samples in releasing area.A total of 128 hatchery-released black sea bream were identified among 487 recaptured samples in ZRE,while a total of 15 samples were identified among 96 samples in DB.In summary,there was a high survival of released fish.Nevertheless,the results provided evidence to consider a loss of genetic variation in hatcheryreleased stock and a negative genetic effect of the stock enhancement.  相似文献   

The Geminga fraction     

Alice K. Harding  Isabelle A. Grenier  Peter L. Gonthier 《Astrophysics and Space Science》2007,309(1-4):221-230

Radio-quiet γ-ray pulsars like Geminga may account for a number of the unidentified EGRET sources in the Galaxy. The number of Geminga-like pulsars is very sensitive to the geometry of both the γ-ray and radio beams. Recent studies of the shape and polarization of pulse profiles of young radio pulsars have provided evidence that their radio emission originates in wide cone beams at altitudes that are a significant fraction (1–10%) of their light cylinder radius. Such wide radio emission beams will be visible at a much larger range of observer angles than the narrow core components thought to originate at lower altitude. Using 3D geometrical modeling that includes relativistic effects from pulsar rotation, we study the visibility of such radio cone beams as well as that of the γ-ray beams predicted by slot gap and outer gap models. From the results of this study, one can obtain revised predictions for the fraction of Geminga-like, radio quiet pulsars present in the γ-ray pulsar population.   相似文献   

Requirements for observations from chemodynamical models     

John S. Gallagher 《Astrophysics and Space Science》2003,284(2):313-322

Chemodynamical models view the evolution of galaxies in the context of an ISM that is influenced both by the stars that it has made and the effects of the gravitational potential of the host system. While these models include complicated interactions within galaxies, they also exhibit general features, such as regulated star formation rates, mixing between various gas phases in the interstellar medium, and the transport of metals over large distances. These predictions are the basis for initial observational tests of the models, where good qualitative agreement is found, and offer a foundation for future quantitative comparisons with chemodynamical models. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

基于微卫星的泥蚶5个地理群体遗传多样性分析   总被引：1，自引：0，他引：1  

程雪艳  滕爽爽  肖国强  邵艳卿  张炯明  方军  柴雪良 《海洋科学》2015,39(11):116-125

为了研究泥蚶不同地理群体的系统发育关系和遗传多样性,运用微卫星DNA标记,对浙江温州(ZJ)、山东日照(SD)、韩国釜山(KR)、广西企沙(GX)、海南海口(HN)等5个泥蚶地理群体进行了17个基因位点的遗传多样性分析。结果显示,从17对引物中共检测出115个等位基因,每个位点等位基因数(Na)2~12个。有效等位基因数(Ne)为1.192~7.849,平均观测杂合度(Ho)为0.430~0.516,平均期望杂合度(He)为0.573~0.656,5个群体的平均多态信息含量(PIC)为0.525~0.608。Hardy-Weinberg平衡检验表明,51.2%的微卫星位点偏离平衡状态(P0.05)。5个群体间的种群遗传分化系数(FST)为0.012~0.062,呈现出较低的遗传分化。UPMGA聚类分析表明,浙江群体和韩国群体首先聚在一起,亲缘关系最近,然后与海南群体聚合;广西群体和山东群体亲缘关系较近,聚为一支,然后与上面三个群体聚合。  相似文献   

Radio-Loud and Radio-Quiet Gamma-Ray Pulsars from the Galaxy and the Gould Belt     

P. L. Gonthier  R. Van Guilder  A. K. Harding  I. A. Grenier  C. A. Perrot 《Astrophysics and Space Science》2005,297(1-4):71-80

We present results of a population synthesis study of radio-loud and radio-quiet γ-ray pulsars from the Galactic plane and the Gould Belt. The simulation includes the Parkes multibeam pulsar survey, realistic beam geometries for radio and γ-ray emission from neutron stars and the new electron density model of Cordes and Lazio. Normalizing to the number of radio pulsars observed by a set of nine radio surveys, the simulation suggests a neutron star birth rate of 1.4 neutron stars per century in the Galactic plane. In addition, the simulation predicts 19 radio-loud and 7 radio-quiet γ-ray pulsars from the plane that EGRET should have observed as point sources. Assuming that during the last 5 Myr the Gould Belt produced 100 neutron stars, only 10 of these would be observed as radio pulsars with three radio-loud and four radio-quiet γ-ray pulsars observed by EGRET. These results are in general agreement with the recent number of about 25 EGRET error boxes that contain Parkes radio pulsars. Since the Gould Belt pulsars are relatively close by, the selection of EGRET radio-quiet γ-ray pulsars strongly favors large impact angles, β, in the viewing geometry where the off-beam emission from curvature radiation provides the γ-ray flux. Therefore, the simulated EGRET radio-quiet γ-ray pulsars, being young and nearby, most closely reflect the current shape of the Gould Belt suggesting that such sources may significantly contribute to the EGRET unidentified γ-ray sources correlated with the Gould Belt.  相似文献   

Genetic variability analysis in five populations of the sea cucumber Stichopus (Apostichopus) japonicus from China,Russia, South Korea and Japan as revealed by microsatellite markers     

Yaqing Chang  Zhigang Feng  Jiaping Yu  Jun Ding 《Marine Ecology》2009,30(4):455-461

The genetic structure of populations of the sea cucumber Stichopus (Apostichopus) japonicus was investigated using 10 microsatellite markers. In all, 152 individuals from five natural populations were collected from Aomori, Japan (JA and JR), Yosu, South Korea (KY), Dalian, China (CD) and Vladivostock, Russia (RV). A total of 145 alleles were found at 10 loci. The number of alleles per locus ranged from 9 at PSC03 to 20 at SCZ06, with an average of 14.5. Average H_o and H_e ranged from 0.260 (JR) to 0.434 (JA) and from 0.654 (RV) to 0.778 (KY), respectively. No significant differences at A, H_o and H_e were found, indicating similar genetic diversity in the five populations. A single allele was found at the PSC05 locus in the RV population. Of the 50 loci, 42 significantly deviated from Hardy–Weinberg equilibrium, all showing heterozygote deficiency. The genetic distances were all relatively great, ranging from 0.497 (between JA and KY) to 1.029 (between KY and JR). This suggests the five populations are genetically distinct. Cluster analysis indicated that JA, KY and CD form one branch and RV and JR another in the UPGMA tree. A hypothesis is proposed for the evolution of the Japanese red sea cucumbers and the genetic relationship among the populations.  相似文献   

中国近海条石鲷(Oplegnathus fasciatus)群体遗传多样性线粒体DNA序列分析     

肖永双  程起群  任桂静  李军  马道远  徐世宏  刘清华  肖志忠  韩志强 《海洋与湖沼》2013,44(2):427-432

采用线粒体(mtDNA)DNACOI和Cytb基因片段序列分析方法,进行了中国近海条石鲷(Oplegnathus fasciatus)舟山和胶南群体遗传多样性及其遗传结构现状研究。结果表明,基于mtDNACOI分子标记揭示条石鲷舟山群体遗传多样性水平(h=0.814±0.060,π=0.009±0.005,k=5.653±2.789)显著高于胶南群体(h=0.742±0.116,π=0.003±0.002,k=1.970±1.196);MST分析、NJ系统分析和核苷酸不配对分布分析结果皆显示两群体内存在三个显著分化的单倍型类群,支系间的遗传距离为0.018—0.025;遗传分化指数结果(Fst=0.331,P=0.000)和确切P检验结果显示(P=0.000)两群体间存在显著遗传分化。基于mtDNACytb分子标记显示条石鲷群体遗传多样性总体上呈现较低水平(h=0.874±0.023,π=0.006±0.003,k=2.761±1.492),舟山群体核苷酸多样度水平显著高于胶南群体;NJ系统发育和群体遗传分化研究结果显示,条石鲷群体间未检测到显著的遗传分化。  相似文献   

Integrating Undergraduate Fieldwork into the Study of Human Mobility     

Elin Charles-Edwards  Martin Bell  Jonathan Corcoran 《The Australian geographer》2014,45(4):505-519

Fieldwork has long been fundamental to human geography; however, increasingly unreceptive institutional environments have led to a decline in fieldwork in undergraduate human geography programs. We argue that mobility research presents an opportunity to reinvigorate the undergraduate field trip in human geography. We report on a second-year field course to Noosa, Australia, that blends new technologies with conventional survey techniques to capture data on a spectrum of human spatial behaviour. Over the course of a single weekend, students collect GPS traces of tourist mobility, survey businesses on the journey to work, collect residential migration histories and trace population dynamics on Noosa beach. Over the three years the course has been running, students have constructed a large repository of data on this Australian mobility hotspot, of which we report highlights. Results from standardised student course evaluations confirm the pedagogical value of these initiatives for human geography undergraduates.  相似文献   

鄂尔多斯半日花居群间营养器官的解剖学研究   总被引：2，自引：0，他引：2  

马虹  王立  曹瑞  姜波 《中国沙漠》2005,25(3):437-441

对鄂尔多斯半日花不同居群间营养器官进行解剖学比较和分析,发现它们都具明显的旱生植物特征。但是由于其生境不同,叶表现为宽叶与细叶两种类型生长于沟边坡下较湿润环境的植株的叶较宽,一般不反卷,称其为宽叶型;生长于干燥阳坡上较干旱环境的植株的叶较窄,常反卷为针形,称其为细叶型。宽叶型的叶比细叶型的叶宽、长、厚,但角质层比细叶型薄,表皮毛比细叶型少,外切向壁不加厚,叶肉有栅栏组织和海绵组织的区别,上表皮气孔不下陷,由大型薄壁细胞形成维管束鞘。细叶型的叶上表皮气孔强烈下陷,叶肉无栅栏组织和海绵组织的区别,由木质化或栓质化细胞形成维管束鞘。同时,将鄂尔多斯半日花与其他几种旱生、中生植物叶的解剖特征进行了比较,其解剖学特征基本同其他几种旱生植物。  相似文献