舟山群岛海域5种鳗的营养生态位及种间关系

海鳗等鳗鲡目鱼类是舟山群岛海域常见的近底层凶猛肉食性鱼类,研究鳗类的营养生态位可以了解其在舟山群岛海域生态系统中占据的营养层次。本研究以舟山群岛海域的海鳗（Muraenesox cinereus）、前肛鳗（Dysomma anguillare）、星康吉鳗（Conger myriaster）、食蟹豆齿鳗（Pisodonophis cancrivorus）和短尾吻鳗（Rhynchoconger ectenurus）为研究对象,利用碳氮稳定同位素技术分析这5种鳗的营养生态位及种间食物关系。结果显示：（1）舟山群岛海域5种鳗的δ13C范围是-21.91‰~-14.97‰（平均值-17.03±1.14‰）,δ15N范围为9.56‰~15.13‰（平均值11.50±1.36‰）;（2）非参数检验结果表明,不同物种间的碳氮稳定同位素比值之间均存在极显著差异;Pearson相关性分析表明,5种鳗总体的δ13C、δ15N值与肛长相关性均不显著,而除前肛鳗以外,其余4种鳗总体的δ13C值与肛长相关性不显著,δ15N值与肛长呈极显著正相关;（3）稳定同位素混合模型（SIAR）显示鱼类、虾类和口足类是鳗类的主要食物来源;（4）海鳗与其他4种鳗的营养生态位均有重叠,说明它们之间的食源有一定程度的同质化,存在食物竞争;食蟹豆齿鳗和短尾吻鳗的校正核心生态位面积（SEAc）最大,说明二者食性泛化,其摄食类群主要取决于饵料生物的易得性;前肛鳗、星康吉鳗和短尾吻鳗之间不存在生态位重叠,说明其摄食种类有所分化,体现了同域分布近缘种的食性差异。本研究阐述了舟山群岛海域5种鳗的种间食物关系和进化共存机制,可为研究舟山群岛海域高营养级类群的食物网结构特征提供参考。     

水稻幼穗分化期间减源对源库关系的影响

为探讨水稻幼穗分化期间源的大小对库的分化发育和光合生产及运输的影响,对供试的４个水稻品种在幼穗分化不同时期进行剪叶处理,通过测定光合速率（Ｐｎ）、净同化率（ＮＡＲ）、源器官非结构碳水化合物含量及其在可运转态和不可运转态间的分配,以及有关源、库、流活性的部分生理生化指标,并采用同位素示踪技术等,考察了源库互作关系,干物质生产和体内物质分配的变化,源、库、流活性变化动态和产量性状。结果表明,改变库源比     

Cytogenetic studies of the interspecific hybrids between Hystrix longearistata in Japan and Hystrix duthiei in China

Cytogenetic studies of Hystrix duthiei (2n=28) from China, Hystrix longearistata (2n=28) from Japan and their artificial hybrids were carried out. The F1 hybrids showed a very high degree of bivalent pairing at the meiotic Metaphase-I. No multivalents were found. Partial fertility of the hybrids was observed. The results indicated that they shared two highly homologous genomes and were closely related.     

农业机械化与农村工业化量化关系分析

根据农业机械化与农村工业化的相互作用的关系,建立了农业机械化与农村工业化发展水平,农业机械化与农村工业化对农村资源配置的影响关系表达式;通过对农业机械经,农村工业化因素间的关联性分析,确定了影响农业机械化,农村工业化发展的主导因素。     

水稻灌浆结实期减源疏库对源库关系的影响

大穗型水稻品种超丰早和中穗型品种湘早籼13,齐穗后进行剪叶疏粒处理创造不同的库源比例,重点考察了源库互作关系,干物质生产和分配,源、库、流活性的动态变化和产量性状等。结果表明,库对源具有反馈促进作用,库／源比高和库容量大的处理净同化率（NAR）较高,茎鞘和叶中非结构碳水化合物滞留量少,14C同化物向籽粒输送比例增加,输导组织和库器官活性趋于增强。     

Genetic linkage maps of Citrus sunki Hort. ex. Tan. and Poncirus trifoliata (L.) Raf. and mapping of citrus tristeza virus resistance gene

The RAPD technique was used to identify genetic relationships in 19 accessions, including six species of the genus Chenopodium. A dendrogram was constructed using UPGMA from 399 DNA markers. The molecular data clustered species and accessions into five different groups. Group 1 with three cultivated varieties of C. nuttalliae, Group 2 included eight cultivars and two wild varieties of C. quinoa, Group 3 with C. berlandieri and C. album, Group 4 with two accessions of C. pallidicaule, and Group 5 with 2 accessions of C. ambrosioides. The polymorphic patterns generated by RAPD profiles showed different degrees of genetic relationship among the species studied. A low level of intraspecific variation was found within the accessions of C. quinoa, C. nuttalliae, and C. pallidicaule. The RAPD markers were found to be a useful tool for detecting genetic variation within the genus Chenopodium.     

云斑尖塘鳢、线纹尖塘鳢及其杂交子一代间的遗传关系

应用RAPD技术研究云斑尖塘鳢、线纹尖塘鳢及其杂交子一代(F1)间的遗传关系。筛选得到25个随机引物均在亲本和杂交子一代间呈现多态,遗传相似性指数和遗传距离的计算结果显示,正交F1(云斑尖塘鳢♂×线纹尖塘鳢♀)与母本平均遗传相似系数(0.7090)高于与父本平均遗传相似系数(0.5948);反交F1(云斑尖塘鳢♀×线纹尖塘鳢♂)与母本平均遗传相似系数(0.6301)也高于与父本平均遗传相似系数(0.6089)。说明正反交子代在遗传关系上均偏向各自的母本,对扩增带和聚类图的分析均得到这一结果,表明F1所接受的双亲遗传物质并非完全对等的,所获得的遗传信息可能更多来自母本。     

Estimating fisheries reference points from catch and resilience

This study presents a Monte Carlo method (CMSY) for estimating fisheries reference points from catch, resilience and qualitative stock status information on data‐limited stocks. It also presents a Bayesian state‐space implementation of the Schaefer production model (BSM), fitted to catch and biomass or catch‐per‐unit‐of‐effort (CPUE) data. Special emphasis was given to derive informative priors for productivity, unexploited stock size, catchability and biomass from population dynamics theory. Both models gave good predictions of the maximum intrinsic rate of population increase r, unexploited stock size k and maximum sustainable yield MSY when validated against simulated data with known parameter values. CMSY provided, in addition, reasonable predictions of relative biomass and exploitation rate. Both models were evaluated against 128 real stocks, where estimates of biomass were available from full stock assessments. BSM estimates of r, k and MSY were used as benchmarks for the respective CMSY estimates and were not significantly different in 76% of the stocks. A similar test against 28 data‐limited stocks, where CPUE instead of biomass was available, showed that BSM and CMSY estimates of r, k and MSY were not significantly different in 89% of the stocks. Both CMSY and BSM combine the production model with a simple stock–recruitment model, accounting for reduced recruitment at severely depleted stock sizes.     

东黄海沙海蜇与口冠水母分类关系的辨析-基于核糖体18SrDNA基因序列

近年在东黄海形成大规模暴发的大型水母沙海蜇(Nemopilema nomurai)在大量文献中常被等同于口冠水母(Stomolophus meleagris)的同物异名,为澄清沙海蜇与口冠水母之间一直混淆不清的分类关系,现首次从分子遗传学水平进行辨析,采用聚合酶链式反应(PCR)技术对东黄海沙海蜇的18SrDNA(核糖...     

三角帆蚌对蓝藻的滤食作用及其对沉水植物生长的影响

双壳贝类是淡水生态系统常见的滤食性动物,以浮游植物和有机物悬浮颗粒为食,其作用可能降低蓝藻浓度,从而促进沉水植物生长。通过构建4组(草+蓝藻、草+蓝藻+低生物量蚌、草+蓝藻+高生物量蚌、草)室外微型生态系统,研究了湖泊下风区常见蓝藻堆积浓度下,三角帆蚌(Hyriopsis cumingii)的滤食作用对蓝藻水华和沉水植物苦草(Vallisneria natans)生长的影响。结果表明:(1)蓝藻对苦草的生长具有显著抑制作用,草藻组和草组的相对生长率分别为-7.65mg/g·d和7.19mg/g·d;(2)三角帆蚌对蓝藻具有明显的下行滤食压力,其大小与蚌生物量有关,蚌生物量高时效果明显;(3)三角帆蚌的滤食可以不同程度上缓解蓝藻对苦草的生长抑制,低蚌组和高蚌组苦草相对生长率分别为-5.31mg/g·d和4.24mg/g·d。蓝藻颗粒被滤食后,水体光照条件的改善可能是有蚌组苦草生物量相对较高的主要原因。说明双壳贝类可以通过滤食浮游植物使水体理化环境向着有利于沉水植物生长的方向发展,但这种作用的大小与贝类生物量的合理配置有密切关系。