东南亚猪的遗传育种

简要地回顾了东南亚猪近50年来的猪品种改良历程,重点阐述了泰国正大集团在猪育种上的发展过程,分析了现行的猪繁育体系结构.对猪育种的基本原则、性状遗传相关的影响、杂种优势的利用、育种与环境的关系、市场需求导向等进行了讨论.在总结作者从事养猪生产50余年经验的基础上,对目前东南亚猪的育种提出了有参考价值的建议.     

Significance of two different ranking methods for studying fish fauna: a case study on the fish fauna from upper and middle portions from Mekong River

Studies on fish fauna should not only focus on fish composition and the comparison of fish composition among the study region and adjacent regions, but should also explore the origin and uniqueness of different taxa as well as the substitution of genera and species. In this study, the value of floristic presence method was modified and renamed the value of fish fauna presence (VFFP) method. The specific steps of the VFFP method and the traditional fish fauna analysis (TFFA) method were refined and standardized. Then, the VFFP and TFFA methods were applied to study the fish fauna of the upper and middle portions of the Mekong River basin. The results indicate that the TFFA method reflects the families (subfamilies) and genera that constitute the main body of fish in the studied river basin. The results of the VFFP method show which families (subfamilies) and genera are representative for the basin. Therefore, combining the TFFA and VFFP methods to analyze the composition of fish fauna can reflect the characteristics of fish fauna from different perspectives. The case study shows that the fish fauna of the Mekong River is a part of the fish fauna of Southeast Asia. Although it shows some similarities to the composition of South Asian fish fauna, it does not belong to the South Asian fish fauna as a whole, and is essentially different from the East Asian fish fauna. This study provides an objective, quantitative, and verifiable method for studying fish fauna.     

水分条件对巴音布鲁克高寒湿地CO_2排放的影响

在新疆天山中部巴音布鲁克天鹅湖高寒湿地,以苔草(Carex tristachya)为主要建群种的样地为研究对象,利用英国PP-systems公司生产的便携式土壤呼吸测定系统(CIRAS-2-SRC)研究了不同地表水分条件对天鹅湖高寒湿地夏季土壤CO2排放的影响。结果表明,1)湿润区的生物量大于干燥区;干燥区土壤CO2排放高于湿润区,干燥区土壤CO2排放日变化曲线为单峰曲线,CO2排放最高点出现在当地14:00-16:00,最高值为1.185 0g CO2·m-2·h-1;湿润区土壤CO2排放日变化曲线为双峰曲线,两个峰值分别出现在12:00和16:00,最高值为1.024 0g CO2·m-2·h-1。2)不同水分条件下生物量中凋落物含量影响土壤CO2排放。土壤温度是CO2排放的主要限制因子,且地表干燥区CO2排放与土壤温度的相关性更显著(P0.01)。土壤湿度与CO2排放相关性不显著(P湿润区=0.997,P干燥区=0.409)。     

Exploring tropical fisheries through fishers’ perceptions: Fishing down the food web in the Tonlé Sap,Cambodia

Tropical fisheries are among the most productive fisheries in the world, often providing the primary source of protein for the local population. Despite their importance, data on these systems are relatively limited, thus hampering management and policy development. Here, the implications of increasing fishing pressure are explored by critically evaluating the perceptions of the fishers who rely on these ecosystems to survive. A total of 169 fishers in 26 different fish‐dependent communities in the Tonlé Sap Lake, Cambodia, were surveyed to understand their perceptions of the impact that fishing has had on the ecosystem. The Tonlé Sap is one of the largest, yet poorest studied, freshwater fisheries in the world. Consistent with “fishing down the food web” theory of fisheries, survey data revealed that although fishers observed the total size of fish catch remaining consistent over recent years there has been a drastic decline in the size of individual fish, as well as a reduction in the diversity of species caught. These perceptions are examined with reference to food web theories that explore how fishing pressure leads to ecosystem change, including the more recent “indiscriminate fisheries” theory.     

宁夏绿洲禾豆牧草混播组合及其比例效应

在宁夏中部半干旱带有补灌的条件下,以紫花苜蓿(Medicago sativa)、沙打旺(Astragalus adsurgens)、羊草(Leymus chinensis)和老芒麦(Elymus sibiricus)为试验材料,豆科与禾本科牧草分别按照3∶7、5∶5、7∶3共3种不同比例进行混播,研究了不同混播组合及比例对其经济投入产出比、干草及主要营养成分产量、相对总产量及竞争力等方面的影响。两年的试验结果表明,3种豆禾牧草混播比例的产量均显著大于单播禾本科牧草的产量(P0.05)。苜蓿与禾本科牧草混播组合2013年及2014年的产量均显著高于沙打旺与禾本科牧草的混播组合(P0.05),其中,紫花苜蓿∶羊草为7∶3的混播组合的产量为最高(P0.05),粗蛋白和粗脂肪的总产量最高且投入产出比最低。紫花苜蓿+禾草组合中豆科牧草竞争力均大于相同比例下沙打旺+禾本科牧草组合中豆科牧草竞争力。沙打旺+禾本科牧草混播组合中,相对总产量（RYT）大于1的组合多于紫花苜蓿+禾本科牧草混播组合,其中,沙打旺∶羊草为7∶3的混播组合的两年平均RYT最高。以上结果说明,在宁夏中部半干旱带建植栽培草地时,紫花苜蓿∶羊草为7∶3的混播组合有较好的产量效应和最低的投入产出比;而沙打旺∶羊草为7∶3的混播组合中不同物种生长较为均衡。     

Variations in body condition of green turtles (Chelonia mydas) in two nearby foraging grounds indicate their sensitivity to foraging habitats

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