Two decades of suspect evidence for adaptive molecular evolution—negative selection confounding positive-selection signals

There has been a large literature in the last two decades affirming adaptive DNA sequence evolution between species. The main lines of evidence are from (i) the McDonald-Kreitman (MK) test, which compares divergence and polymorphism data, and (ii) the phylogenetic analysis by maximum likelihood (PAML) test, which analyzes multispecies divergence data. Here, we apply these two tests concurrently to genomic data of Drosophila and Arabidopsis. To our surprise, the >100 genes identified by the two tests do not overlap beyond random expectation. Because the non-concordance could be due to low powers leading to high false negatives, we merge every 20–30 genes into a ‘supergene’. At the supergene level, the power of detection is large but the calls still do not overlap. We rule out methodological reasons for the non-concordance. In particular, extensive simulations fail to find scenarios whereby positive selection can only be detected by either MK or PAML, but not both. Since molecular evolution is governed by positive and negative selection concurrently, a fundamental assumption for estimating one of these (say, positive selection) is that the other is constant. However, in a broad survey of primates, birds, Drosophila and Arabidopsis, we found that negative selection rarely stays constant for long in evolution. As a consequence, the variation in negative selection is often misconstrued as a signal of positive selection. In conclusion, MK, PAML and any method that examines genomic sequence evolution has to explicitly address the variation in negative selection before estimating positive selection. In a companion study, we propose a possible path forward in two stages—first, by mapping out the changes in negative selection and then using this map to estimate positive selection. For now, the large literature on positive selection between species has to await reassessment.     

跳远运动员的选材与预测

本文从系统论和遗传学的角度,运用文献资料综述法和分析法,探讨如何控制跳远运动员的选材过程,并从生理、心理、身体素质等方面进行了研究,选出优秀的苗子进行早期培养,缩短成长周期,提高成材率。     

我国文献信息管理系统灾难备份的思考

数据的大集中有利于信息服务,但放大了数据灾难。在各类灾难备份(以下简称“灾备”)方案纷纷投向市场的今天,文献信息管理系统灾备方案的选择预伏了风险。怎样考虑灾备方案的建立,我国数字信息面临哪些灾难,哪些灾难可能通过科学的管理化解或降低其危害程度,文献信息管理系统如何选择灾备级别,我国图书馆、档案馆灾备中心建设的模式选择等,都是这篇文章讨论的焦点。     

部分国家和地区体育彩票经销商遴选政策分析及启示

采用政策分析法分析与我国体育彩票销售体系相似,经销商遴选方式趋同的部分国家和地区的体育彩票业经销商遴选政策,具体包括新加坡、 美国、西班牙、澳大利亚、新西兰、加拿大6 个国家及地区,寻找不同国家和地区政策分析的规律性特点,即均有基本资格审核,注重道德品质和遵纪守 法;注重是否具备营销、管理能力;要求体育彩票经销商有运动兴趣和博彩知识;将经销人员培训纳入彩票业务体系之中;重视经销地点选择和店面规 格;技术供应商执照与经销商执照不得同有。在分析其特征的基础上,与国际体育彩票经销商政策比较发现,得出对我国现行体育彩票经销商政策的 借鉴和启示,目前我国体育彩票经销商遴选仍有许多相关内容的考量值得借鉴和参考,即关于经济利害关系人的考量;关于运动兴趣和体育专业知识 的考量;关于“负责任博彩”的考量;关于推行“体育彩票经理人”职业资格认证制度的考量;关于技术供应商执照与经销商执照不得同有的考量,通过 部分国家或地区体育彩票经销商遴选政策分析研究,希望能够为我国体育彩票业经销商遴选政策的完善与发展提供智力支持和学术支撑。     

基于胜任特征的校长遴选与培训体系

校长胜任特征模型是指担任校长角色、完成校长岗位职责所需要具备的胜任特征的总和。基于胜任特征的校长遴选体系包括遴选标准、遴选标准的提炼、遴选流程、遴选技术等要素,基于胜任特征的校长培训体系包括培训需求分析、培训课程规划、培训行为设计和培训效果评估等要素。从解决我国中小学校长遴选、培训制度中存在的问题来说,这一模型具有重要的人力资源管理价值。     

Natural selection contributes to the myopia epidemic

The prevalence of myopia, or nearsightedness, has skyrocketed in the past few decades, creating a public health crisis that is commonly attributed to lifestyle changes. Here we report an overall increase in the frequencies of myopia-associated mutant alleles over 25 years among participants of the UK Biobank. Although myopia itself appears to be selected against, many of the mutant alleles are associated with reproductive benefits, suggesting that reproduction-related selection inadvertently contributes to the myopia epidemic. We estimate that, in the UK alone, natural selection adds more than 100 000 myopia cases per generation, and argue that antagonistic pleiotropy be broadly considered in explaining the spreads of apparently disadvantageous phenotypes in humans and beyond.     

高等职业院校的发展战略选择--赴英国牛津大学研修的感悟

提出了高等职业院校发展战略的内涵，分析了对高等职业院校发展战略的选择需要思考的几个问题，探讨了高等职业学校发展战略的模式选择。     

从内容特色看苏教版国标本初中语文实验教科书的创新点

教材改革是教材编写思想、教材内容以及教材教法、学法改革的文本载体."苏教版"国标本初中语文实验教科书以其独特的结构特征和鲜明的内容特点在同时期国家教育部审查通过的三种主要的初中语文教材中脱颖而出.文章试从教材选文标准、内容组合、价值取向以及弹性设计等方面来分析苏教版国标本初中语文实验教科书的创新点.     

泛函分析框架下论"有效前沿"的存在

文章应用泛函分析理论,构造了随机向量希尔伯特空间,在一定的理论准备下,论证了马科维茨组合选择理论中"有效前沿"的存在.     

公共人力资源管理制度选择的前沿问题研究——决定制度选择的价值因素、安排模式和制度发展新取向

公共人力资源管理制度发展和演变的历史,实际上是价值不断冲突和人们不断寻求价值间相互平衡的历史,这一过程推进了公共人力资源管理制度的发展。同时,人力资源管理的思想最早是产生于企业界的,后来公共部门才逐渐将其从私营部门中引入。因此,公共人力资源管理过程不可避免地越来越多地折射出市场的法则和机制,制度的发展呈现出新的发展取向。