Density estimates of rural dog populations and an assessment of marking methods during a rabies vaccination campaign in the Philippines

We estimated the population density of dogs by distance sampling and assessed the potential utility of two marking methods for capture-mark-recapture applications following a mass canine rabies-vaccination campaign in Sorsogon Province, the Republic of the Philippines. Thirty villages selected to assess vaccine coverage and for dog surveys were visited 1 to 11 days after the vaccinating team. Measurements of the distance of dogs or groups of dogs from transect lines were obtained in 1088 instances (N = 1278 dogs; mean group SIZE = 1.2). Various functions modelling the probability of detection were fitted to a truncated distribution of distances of dogs from transect lines. A hazard rate model provided the best fit and an overall estimate of dog-population density of 468/km² (95% confidence interval, 359 to 611). At vaccination, most dogs were marked with either a paint stick or a black plastic collar. Overall, 34.8% of 2167 and 28.5% of 2115 dogs could be accurately identified as wearing a collar or showing a paint mark; 49.1% of the dogs had either mark. Increasing time interval between vaccination-team visit and dog survey and increasing distance from transect line were inversely associated with the probability of observing a paint mark. Probability of observing a collar was positively associated with increasing estimated density of the dog population in a given village and with animals not associated with a house. The data indicate that distance sampling is a relatively simple and adaptable method for estimating dog-population density and is not prone to problems associated with meeting some model assumptions inherent to mark-recapture estimators.     

Genetic relationships between the dominant genotypes of Phytophthora infestans in Hokkaido, Japan

The genetic characteristics of the dominant genotypes of Phytophthora infestans in Japan (US-1, JP-1, Japanese A1-A, A1-B) were compared. Differences were evident in the peptidase genotype, amplified fragment length polymorphism, and RG57 DNA fingerprints. Almost all of the fingerprint bands for the Japanese genotype A1-B were also present in JP-1 and Japanese A1-A, and few bands were unique to Japanese A1-B. These results suggest that the Japanese A1-B genotype was generated from sexual reproduction involving Japanese A1-A and JP-1 or related genotypes.     

青稞遗传多样性及其农艺性状与SSR标记的关联分析

利用92个SSR标记对108份青稞亲本材料进行多态性扫描,分析其遗传多样性,旨在寻找与农艺性状相关联的分子标记,为青稞杂交组合的配制及分子标记辅助育种提供依据。挑选48个多态性标记进行群体遗传结构分析,在此基础上采用Tassel 2.1 GLM (general linear model)和MLM (mixed linear model)方法进行标记与农艺性状的关联分析。共检测出156个等位变异,每个位点2~6个等位变异。供试群体的Shannon指数为0.6727~1.1368,材料间遗传相似系数为0.2250~1.0000,平均0.7585。通过群体遗传结构分析将供试材料划分成4个亚群。以GLM分析,发现12个与株高、穗长、穗粒数和分蘖数相关联的标记,对表型变异的解释率分别为11.5%~17.6%、19.4%~45.4%、15.4%~22.1%和29.2%;以MLM分析,发现8个与株高、分蘖数和小穗数相关的标记,各标记对表型变异的解释率分别为31.7%~49.8%、28.1%~37.2%、22.7%~32.7%。关联标记分布在基因组全部6个连锁群上。     

Decline and extirpation of an endangered Panamanian stream frog population (Craugastor punctariolus) due to an outbreak of chytridiomycosis

We conducted a mark-recapture study of three subpopulations of Craugastor punctariolus at a mid-elevation site in central Panama between 1999 and 2005. The study spans a period over which the pathogenic fungus Batrachochytrium dendrobatidis (Bd) was absent from the site, invaded the site and decimated all amphibian populations, and now persists. We quantified natural demographic parameters prior to and during an event of mass mortality due to chytridiomycosis caused by Bd. Prior to the event of mass mortality, all three subpopulations of C. punctariolus were large (19-68 animals/200 m), showed a stable age-size distribution, and had high survival. All age-size classes of this species co-occurred on boulder clumps along streams, and adults showed high site fidelity and were likely territorial. Following detection of Bd at this site in late September 2004, four dead C. punctariolus were found infected with Bd and all three subpopulations completely disappeared from this site within 2 months. The association of all age-size classes with microhabitats appropriate for survival and growth of Bd likely contributed to the rapid and severe degree of decline of this species at this site. These data provide insight into the patterns and mechanisms of decline within a species due to Bd.     

变叶海棠种群多样性的形成与分化研究

 采用杂种指数和形象化散点图法, 探明了变叶海棠以兼性无融合生殖方式与陇东海棠和花叶海棠产生渗入杂交变异, 又以无融合生殖方式保持新产生变异的遗传, 经过数千万年的世代繁衍,形成现今这样极其复杂多样的渗入杂交群体, 该群体为3 个种的杂交复合体。由于杂种的全部或部分能育子代中发生的基因重组和增加基因的突变, 丰富了物种的基因库, 从而深入的揭示了变叶海棠具有多种高抗性的遗传机理。在变叶海棠居群内保护或栽植适量的陇东海棠和花叶海棠, 对于保持和促进变叶海棠多样性的形成与分化具有重要意义。     

咖啡黑小蠹的发生规律及药剂防治研究

咖啡黑小蠢是近年在兴隆华侨农场严重危害中粒种咖啡的重要害虫。据1989年对4—5年生咖啡树调查,植株受害率100％,枝条受害率29.7—82.5％,虫害枯枝率7.65—17.8％。该虫以雌成虫钻蛀咖啡枝条为害,幼虫和成虫取食蛀道壁上的真菌菌丝。田间种群数量通常在3月上旬开始剧增,3月中下旬为高峰期,7月至10月田间虫口极少,11月以后逐渐有虫口及虫枯枝出现。温度是影响虫口波动的主要因素。2.5％溴氰菊酶、25％杀虫双、40％乐菊酯各兑水1000倍对成虫直接触杀效果显著,死亡率均为100％。48％乐斯本、40％氧化乐果400—800倍液等12种杀虫剂田间喷雾对咖啡枝条蛀洞内的成虫、蛹、幼虫防效均不明显。     

褐飞虱种群动态的研究 Ⅰ.温度、食料条件对种群增长的影响

褐飞虱未成熟期的发育速率与温度呈逻辑斯蒂曲线关系。除取食秧苗外,在其它生育期稻株上完成一个世代的发育起点温度和有效积温值基本相似,其短翅型世代为10.8℃和434.3日度,长翅型世代为10.7℃和452.4日度。卵的孵化率稳定,受试验温度(17.5—29℃)和水稻生育期影响小,平均孵化率为92％。若虫存活率则明显受温度和食料状况影响。成虫寿命、总产卵量、产卵速率等亦因温度和食料条件的变化而有很大波动。温度在27℃,取食分蘖、拔节期水稻的种群内禀增长能力(r_m)最大。     

The Total Population Prediction of Ya＇an City from 2010 to 2020 Year

利用雅安市1985—2009年的人口统计数据,拟合出马尔萨斯人口模型、Logistic增长模型和一元线性回归模型。通过2006—2009年人口数量的预测值与实际值比较,最终选择模拟精度较高的马尔萨斯模型和Logistic模型对雅安市2010—2020年的总人口做出预测,预测结果表明雅安市2010年的总人口达到156.21万人,而到2020年总人口将达到162.81万人。同时在预测的基础上,探讨了雅安市人口发展的影响因素,为雅安市科学地制定国民经济和社会发展战略,实现人口与资源环境的可持续发展提供参考。     

中国粮食安全百年变化历程

以人粮关系为主线、以中国社会经济发展为辅线,重点回顾了近百余年中国粮食安全变化历程及其社会经济背景。提出粮食安全问题分析的4个纬度,即农民生计、土地制度、农业科技、政策管理。认为重粮重农不轻工商、控制人口过快增长、完善土地使用制度、发展农业科技、维护国家长治久安是保障粮食安全的5个要素。最后指出应树立包括数量安全、结构安全、生态安全、质量安全在内的广义粮食安全观,系统地构建粮食安全保障体系。     

金铁锁居群在水分限制下的叶解剖结构研究(英文)

[目的]对金铁锁居群在水分限制下的叶解剖结构进行研究。[方法]选取引种至实验大田的多年生草本植物金铁锁的2年生实生苗为研究对象,在给水和不给水2种条件下,采用常规石蜡切片法和印迹法,对2个居群的叶解剖结构及气孔的生理特性进行了对比研究。[结果]在冬春季干旱期,不给水栽培条件下的金铁锁表现为叶片上角质层变厚,栅栏组织和海绵组织比值增加,维管束直径增加,主脉木质部维管数增加;叶气孔口变小,气孔密度增加等变化,可以将这些性状的可塑性作为金铁锁居群对水分亏缺作出反应的重要指标。同时,这些指标的变化幅度存在居群间差异。丽江阿西居群在不给水的栽培条件下,叶解剖结构和气孔特性变化显著,从而可能使该居群对干旱环境具有更强的适应能力。[结论]对筛选抗旱金铁锁种质资源及探讨居群在自然干旱条件下的适应性分化具有参考价值。