Paleontology and Chronology of Two Evolutionary Transitions by Hybridization in the Bahamian Land Snail Cerion

The late Quaternary fossil record of the Bahamian land snail Cerion on Great Inagua documents two transitions apparently resulting from hybridization. In the first, a localized modern population represents the hybrid descendants of a 13,000-year-old fossil form from the same area, introgressed with the modern form now characteristic of the adjacent regions. In the second case, a chronocline spanning 15,000 to 20,000 years and expressing the transition of an extinct fossil form to the modern form found on the south coast was documented by morphometry of fossils dated by amino acid racemization and radiocarbon. Hybrid intermediates persisted for many thousands of years.     

农牧民家庭档案管理系统的设计与实现

本文具体介绍了一个农牧民家庭档案管理软件系统,该系统采用数据分散收集、查询与统一集成处理相结合的两级数据库设计结构,既能适应目前基层乡镇独立建立农牧户家庭档案的发展现状,也为进一步向网络化管理平滑过渡建立了统一规范的数据基础.系统实现中针对家庭档案的特点解决了录入数据格式、录入项目灵活设置等问题,满足了家庭档案格式、主题随时间不断扩展、变化的需求.还实现了统计结果查询、多维度统计分析等数据分析的特色功能来为管理决策分析服务.这些功能为建立统一规范、可扩展的实用农牧民家庭档案提供了保障.使该系统成为具体落实农牧户家庭档案工作的一种有效实践手段.     

去除优势种后高寒针茅化草甸群落对增温增雨及其协同作用的响应

2015年6~8月在青海省海北州高寒针茅化草甸草原进行了模拟气候变化及去除优势种紫花针茅(Stipapurpurea)野外控制试验。通过设置增温2℃,增加降雨量20%,研究植物优势种丧失后气候因素对物种多样性和群落稳定性的影响。结果表明:去除紫花针茅后,增温,增雨及两者的交互作用对植物高度、盖度及地上生物量均没有显著影响;增温处理下Shannon-Wiener多样性指数、Simpson优势度指数、Pielou均匀度指数均与对照差异显著(P0.05),说明增温可以提高植物群落的丰富度和均匀度,增雨处理下3个多样性指数均为最高值;去除优势植物紫花针茅后,植物物种数与植物盖度,植物盖度及优势度指数均呈显著正相关。     

川西北高寒草甸对火烧干扰的短期响应

2011年9月对道孚县灌丛草甸火烧后的植物群落特征与土壤环境进行了调查研究。结果表明,火烧对高寒草甸植物群落有显著的负面作用(P0.05),灌丛的盖度、高度、株丛数、基围和生物量均显著减少(P0.05),草本植物群落的盖度、高度和生物量也显著减少(P0.05);火烧对植物群落地上部分的生长有显著的抑制作用(P0.05),但有利于草本植物地下根系的生长,且火烧使高寒草甸草本植物群落的丰富度和多样性指数提高。高寒草甸土壤理化性质和土壤微生物的变化表现为:土壤微生物生物量碳、土壤微生物生物量氮、10-20 cm土层容重和速效磷明显增加(P0.05),而土壤pH值和全钾显著下降(P0.05)。     

A Rare Case of Polyorchidism in a Cat with Four Intra‐abdominal Testes

Polyorchidism is a rare congenital anomaly defined as the presence of more than two histologically proven testes. We report a case of a 9‐month‐old European cat with four intra‐abdominal testes. The diagnosis was performed by means of ultrasonography, intra‐operative examination and histological confirmation. The case reported here presents an extremely rare anomaly, as no previous studies in veterinary medicine have reported the presence of four testes. This case suggests that supernumerary testes should be included as differential diagnoses for intra‐abdominal masses.     

半血野生盘羊与欧拉羊杂交F1代生长发育规律研究

本研究以半血野生盘羊和欧拉羊杂交F1代羊,即含1/4野生盘羊血统羊为素材,对含1/4野生盘羊血统羊生长发育规律进行了分析。结果表明:含1/4野生盘羊血统羊早期生长发育快,体重与体尺间呈极显著的正相关(P0.01),体尺与体重的最优回归方程Y=-37.758+0.431X3+0.529X1,R2=0.962。     

Maturity Effects on Mineral Concentration and Uptake in Annual Ryegrass

ABSTRACT

Annual ryegrass (Lolium multiflorum Lam.) provides livestock feed and captures nutrients from fields receiving manure application. The objective of this study was to determine relationships among maturity and yield, mineral uptake, and mineral concentration. Primary spring growth of ‘Marshall’ ryegrass was harvested every 7 d to 56 d maturity and was fertilized with swine effluent containing 254 and 161 kg nitrogen (N) and 42 and 26 kg phosphorus (P) ha^?1 for two years. Yield increased linearly to a maximum of 13.6 mg ha^?1 after 49 d in 2001 and 8.0 mg ha^?1 after 56 d in 2002. Mineral uptake was highly correlated (r > 0.95) with yield and attained a maximum single harvest of 192 kg N ha^?1 and 32 kg P ha^?1 (mean of two years). Concentration of all minerals except calcium (Ca) declined as ryegrass matured. Low magnesium (Mg) concentration (< 2 g kg^?1 dry matter) increases the risk of hypomagnesemic grass tetany.